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## **Meet the editors**

#### Patricia Price, Editor

The focus of my work is HIV disease - specifically the consequences of beginning ART with low CD4 T-cell counts. This has included studies of Immune Restoration Diseases associated with opportunistic infections that are common in the developing world. We showed that poor control of HCV replication marks Indonesian patients experiencing relapses of HCV disease on ART. A larger study in Jakarta will correlate "the footprint" of chronic CMV infection with clinical endpoints in patients beginning ART. We are also studying CMV immunology at Royal Perth Hospital/University of Western Australia. We are addressing the role of CMV in immunological aging – comparing the footprint of CMV in HIV patients and renal transplant recipients with that seen in healthy individuals of a similar age.

#### Nandini Makwana, Editor

I am pursuing a PhD at the University of Western Australia, and my interest is in the effects of Cytomegalovirus on Natural Killer cells and adaptive immune response in renal transplant patients. I have expertise in tissue culture work, and have worked on Japanese Encephalitits, West Nile and Bagaza virus in National Institute of Virology, India, which is also a WHO collaborating centre for Arboviruses and Haemorrhagic fever reference and research. I have also done in-vitro screening of anti-HIV compounds and microbicides at the National AIDS Research Institute, India, and have gained expertise on setting up human cervical explant cultures. My area of interest is virology and immunology but I also hold a postgraduate certificate degree in clinical research and clinical data management.

#### Samantha Brunt, Editor

Following on from my B.Sc in biomedical science which was completed during 2012, my PhD work focuses on Cytomegalovirus antibody production in HIV patients. This is an interest of a larger project investigating CMV immunity and how it relates to accelerated aging and increased prevalence of age associated diseases, such as cardiovascular disease. I am continuing investigations into the 'footprint' CMV infection leaves on a person's immune system, focusing on B-cell activation and also prevalence of auto-antibodies relative to CMV antibody. My honours work demonstrated a correlation of high CMV antibody titres and increased risk of cardiovascular disease in HIV patients stable on therapy.

Contents

**Preface VII**

**Infection 1**

Patricia Price

Chapter 1 **Hearing Loss in Children with Congenital Cytomegalovirus**

Matthew Bates, Kunda Musonda and Alimuddin Zumla

Ana Maria Sampaio, Ana Carolina Guardia, Arlete Milan, Elaine Cristina Ataíde, Rachel Silveira Bello Stucchi, Sandra Botelho Cecilia

Satoshi Iwasaki and Shin-ich Usami

Chapter 2 **Human Cytomegalovirus (HCMV) Infection in**

Chapter 3 **Management of CMV-Associated Diseases in Immunocompromised Patients 41** A.L. Corona-Nakamura and M.J. Arias-Merino

Chapter 4 **Cytomegalovirus Infection in Liver Transplantation 63**

Costa and Ilka de Fatima Santana Ferreira Boin

Chapter 5 **The Footprint of CMV Infection May Last a Lifetime 77**

Chapter 7 **Cytomegalovirus Tegument Proteins and the Development of**

Chapter 6 **The Oncogenicity of Human Cytomegalovirus 95** Prakash Vishnu and David M. Aboulafia

**Novel Antiviral Therapeutics 111**

John Paul III Tomtishen

**Sub-Saharan Africa 17**

### Contents

#### **Preface XI**


Preface

viduals at risk.

diabetes.

cardiovascular changes.

CMV is a prevalent viral pathogen that rarely causes recognisable symptoms in immu‐ nocompetent hosts. CMV is the strangest virus. It has 200 genes but needs only 30 to replicate. It infects everyone but few people have heard of it. We carry it all our lives but it can rarely be isolated from blood. Up to 23% of CD8 T-cells can be specific for CMV in older healthy adults, despite undetectable viral load. CMV-specific T-cells have a "worn out" phenotype, likely gained from lifelong surveillance of persistent CMV

CMV causes distinct patterns of disease in different classes of immunodeficient pa‐ tients. This includes retinitis in HIV patients, pneumonitis after transplantation and deafness in babies. This book includes chapters focussing on different groups of indi‐

CMV reactivation (in previously seropositive recipients) or primary infection (in any recipient) is the most common infectious complication in renal transplantation. In the 1970's one in three recipients experienced pathologies associated with CMV. In most countries, prophylaxis (valganciclovir) is routinely administered for 12-26 weeks after transplantation. However CMV remains a significant cause of graft loss and the opti‐ mal duration of prophylaxis is unclear. In the longer term, CMV reactivations are im‐ plicated in deterioration in renal function, cardiovascular disease and perhaps type II

CMV has also been anecdotally linked with cardiovascular disease and in vitro studies show increased expression of adhesion molecules in endothelial tissues infected with CMV. One study linked T-cell responses to CMV with cardiovascular symptoms (athe‐ rosclerosis) in HIV patients. CMV-DNA has been found in tissues removed during sur‐ gery for abdominal aortic aneurysm and CMV seropositivity is more frequent in coronary artery disease requiring surgery. In HIV patients, stronger T-cell responses to CMV (considered an indication of exposure to CMV rather protection) associate with

In this book we also consider CMV in the developing world where it has been compre‐ hensively ignored. However this must change as ART is rolled out for HIV patients worldwide and transplantation becomes feasible in South America, Africa and Asia.

Finally we need to understand how infection of so few cells with CMV has such dra‐ matic effects. Perhaps CMV has effects even broader than we realise. CMV is a highly

We need to understand the dynamic role of CMV in these populations.

which re-awakens in response to stresses or inflammation.

### Preface

CMV is a prevalent viral pathogen that rarely causes recognisable symptoms in immu‐ nocompetent hosts. CMV is the strangest virus. It has 200 genes but needs only 30 to replicate. It infects everyone but few people have heard of it. We carry it all our lives but it can rarely be isolated from blood. Up to 23% of CD8 T-cells can be specific for CMV in older healthy adults, despite undetectable viral load. CMV-specific T-cells have a "worn out" phenotype, likely gained from lifelong surveillance of persistent CMV which re-awakens in response to stresses or inflammation.

CMV causes distinct patterns of disease in different classes of immunodeficient pa‐ tients. This includes retinitis in HIV patients, pneumonitis after transplantation and deafness in babies. This book includes chapters focussing on different groups of indi‐ viduals at risk.

CMV reactivation (in previously seropositive recipients) or primary infection (in any recipient) is the most common infectious complication in renal transplantation. In the 1970's one in three recipients experienced pathologies associated with CMV. In most countries, prophylaxis (valganciclovir) is routinely administered for 12-26 weeks after transplantation. However CMV remains a significant cause of graft loss and the opti‐ mal duration of prophylaxis is unclear. In the longer term, CMV reactivations are im‐ plicated in deterioration in renal function, cardiovascular disease and perhaps type II diabetes.

CMV has also been anecdotally linked with cardiovascular disease and in vitro studies show increased expression of adhesion molecules in endothelial tissues infected with CMV. One study linked T-cell responses to CMV with cardiovascular symptoms (athe‐ rosclerosis) in HIV patients. CMV-DNA has been found in tissues removed during sur‐ gery for abdominal aortic aneurysm and CMV seropositivity is more frequent in coronary artery disease requiring surgery. In HIV patients, stronger T-cell responses to CMV (considered an indication of exposure to CMV rather protection) associate with cardiovascular changes.

In this book we also consider CMV in the developing world where it has been compre‐ hensively ignored. However this must change as ART is rolled out for HIV patients worldwide and transplantation becomes feasible in South America, Africa and Asia. We need to understand the dynamic role of CMV in these populations.

Finally we need to understand how infection of so few cells with CMV has such dra‐ matic effects. Perhaps CMV has effects even broader than we realise. CMV is a highly

#### XII Preface

evolved virus. The last chapter discusses the need for novel therapeutics to reduce the impact of CMV infection in at risk groups.

> **Patricia Price** University of Western Australia, Australia

> > **Nandini Makwana** Pune University, India

**Chapter 1**

**Hearing Loss in Children with Congenital**

Sensorineural hearing loss (SNHL) is a common birth defect. The genetic origins of SNHL can be identified in half of the prelingual cases; in the others, SNHL is caused by environmental or unidentified genetic factors. The most common environmental cause of SNHL is congenital cytomegalovirus (CMV) infection. CMV is also the most common cause of intrauterine and congenital viral infection, affecting 0.5% to 2.5% of all live neonates [1]. While 90% of CMVinfected children are asymptomatic at birth, 10% of those exhibit clinically apparent sequelae at birth, including SNHL, mental retardation, motor disability, and microcephaly [1-4]. Recent studies have revealed that children with asymptomatic congenital CMV infection are at risk of late-onset SNHL and/or deterioration of SNHL during early childhood. These developments may not appear until months or even years following birth. The frequency of SNHL associated with asymptomatic congenital CMV infection reportedly ranges from 13% to 24% [5-9]. Although asymptomatic CMV infection is associated with a lower incidence of SNHL than symptomatic CMV infection, SNHL caused by congenital CMV often remains undiagnosed because maternal screening for CMV infection is not routinely conducted and the detection of

Hearing loss is detected in approximately 50% of children with symptomatic congenital CMV infection. In 66% of these patients, hearing loss will deteriorate [3, 11]. Children with symptomatic congenital CMV infection are easily identified at birth. In children with symptomatic infection, intrauterine growth retardation and petechiae have been associat‐ ed with the development of hearing loss [12]. SNHL is diagnosed in 7%–25% of children with asymptomatic congenital CMV infection. Rates of delayed-onset SNHL, progressive SNHL, and improvement of SNHL are reported to be 11%–18%, 23%–62%, and 23% –

and reproduction in any medium, provided the original work is properly cited.

© 2013 Iwasaki and Usami; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

SNHL during newborn hearing screening (NHS) tests is difficult [7, 10].

**Cytomegalovirus Infection**

Satoshi Iwasaki and Shin-ich Usami

http://dx.doi.org/10.5772/56160

**1. Introduction**

47%, respectively [5-9].

Additional information is available at the end of the chapter

**Samantha Brunt** University of Western Australia, Australia

### **Hearing Loss in Children with Congenital Cytomegalovirus Infection**

Satoshi Iwasaki and Shin-ich Usami

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/56160

#### **1. Introduction**

evolved virus. The last chapter discusses the need for novel therapeutics to reduce the

**Patricia Price**

**Nandini Makwana** Pune University, India

**Samantha Brunt**

University of Western Australia, Australia

University of Western Australia, Australia

impact of CMV infection in at risk groups.

VIII Preface

Sensorineural hearing loss (SNHL) is a common birth defect. The genetic origins of SNHL can be identified in half of the prelingual cases; in the others, SNHL is caused by environmental or unidentified genetic factors. The most common environmental cause of SNHL is congenital cytomegalovirus (CMV) infection. CMV is also the most common cause of intrauterine and congenital viral infection, affecting 0.5% to 2.5% of all live neonates [1]. While 90% of CMVinfected children are asymptomatic at birth, 10% of those exhibit clinically apparent sequelae at birth, including SNHL, mental retardation, motor disability, and microcephaly [1-4]. Recent studies have revealed that children with asymptomatic congenital CMV infection are at risk of late-onset SNHL and/or deterioration of SNHL during early childhood. These developments may not appear until months or even years following birth. The frequency of SNHL associated with asymptomatic congenital CMV infection reportedly ranges from 13% to 24% [5-9]. Although asymptomatic CMV infection is associated with a lower incidence of SNHL than symptomatic CMV infection, SNHL caused by congenital CMV often remains undiagnosed because maternal screening for CMV infection is not routinely conducted and the detection of SNHL during newborn hearing screening (NHS) tests is difficult [7, 10].

Hearing loss is detected in approximately 50% of children with symptomatic congenital CMV infection. In 66% of these patients, hearing loss will deteriorate [3, 11]. Children with symptomatic congenital CMV infection are easily identified at birth. In children with symptomatic infection, intrauterine growth retardation and petechiae have been associat‐ ed with the development of hearing loss [12]. SNHL is diagnosed in 7%–25% of children with asymptomatic congenital CMV infection. Rates of delayed-onset SNHL, progressive SNHL, and improvement of SNHL are reported to be 11%–18%, 23%–62%, and 23% – 47%, respectively [5-9].

© 2013 Iwasaki and Usami; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Thus, the incidence of asymptomatic CMV infection and resulting SNHL may be higher, making it the leading cause of SNHL in children. Treatment of children with congenital CMV infection can prevent late-onset SNHL and/or deterioration of SNHL during early childhood. Cochlear implantation is also effective for the development of speech perception and auditory skills for deaf children with congenital CMV infection. Therefore, early identification of congenital CMV infection is very important.

improvement of hearing loss from the initial abnormal ABR (profound unilateral loss and

ABR: unilateral moderate hearing loss

Hearing Loss in Children with Congenital Cytomegalovirus Infection

http://dx.doi.org/10.5772/56160

3

ABR: unilateral profound hearing loss

ABR: normal

**Table 1.** Initial symptoms and audiologic results during the first 6 months of life in 18 children with congenital CMV

**Age Hearing loss Characteristic**

Delayed-onset Progressive

Fluctuating Improvement

Improvement

Delayed-onset Progressive

Cochlear implantation

Normal speech development

Normal speech development

Cochlear implantation

(39 mo)

Fluctuating Normal speech development

(29 mo)

**Initial hearing loss Results of follow-up audiologic examination Outcome**

profound

moderate

profound

**Table 2.** Results of longitudinal audiologic examinations in 5 children with SNHL caused by asymptomatic CMV

mild

26 mo Bilateral

Case 4 Bilateral severe 17 mo Normal Fluctuating

SNHL: sensorineural hearing loss. This table is cited from reference [11].

36 mo Bilateral

**Symptoms Audiologic examinations**

Case 1 Not found Automatic ABR: unilateral REFER

Case 6-16 Not found ABR: normal

ABR: auditory brainstem response. This table is cited from reference [11].

Ventricular dilatation

Ventricular dilatation Heart anomaly

Case 2 Unilateral moderate 53 mo Unilateral

Case 3 Unilateral profound 53 mo Unilateral

Case 2 Not found ABR: unilateral moderate hearing loss Case 3 Not found ABR: unilateral profound hearing loss Case 4 Not found ABR: bilateral severe hearing loss Case 5 Not found Automatic ABR: bilateral PASS

profound bilateral loss, respectively).

Case 17 Microcephaly

Case 18 Microcephaly

Case 1 Unilateral moderate (Unilateral REFER)

Case 5 Normal

infection.

(Bilateral PASS)

infection.

### **2. Epidemiology of hearing-impaired children with congenital CMV infection**

Of the 12,599 pregnant women included in a prospective study [13] conducted where from June 1996 to December 2003, maternal ages were as follows: <20 years, 1.6%; 20–24 years, 14.7%; 25–29 years, 41.4%; 30–34 years, 28.6%; 35–39 years, 7.9%; and >40 years, 0.8%. The annual seropositivity rate decreased over the 8-year study period, particularly during the last 4 years. The seropositivity rate of CMV immunoglobulin G (IgG) antibody was 75.3% in the sample as a whole. The seronegativity rate was 23.6%, and the percentage of cases borderline positive for IgG antibody was 1%. The seronegativity rate of CMV IgM antibody was 94.8% in the sample as a whole. The seropositivity rate was 2.2%, and 3% of cases were borderline positive for CMV IgM antibody. During the study period, in the cases positive for IgM antibody (n = 146), borderline positive for IgM antibody (n = 73), and borderline positive for IgG antibody (n = 14) and in cases with seroconversion of IgG antibody (n = 3), neonatal urine was analyzed for CMV DNA. Seroconversion of CMV IgG antibody occurred in 0.32% of the 929 cases negative for IgG antibody. Congenital CMV infection was identified in 18 infants by polymer‐ ase chain reaction (PCR) analysis of urine. Follow-up was conducted in these cases.

The symptoms at birth and sequelae observed during the first 6 months of life in the 18 children with congenital CMV infection are shown in Table 1. Among these infants, 2 children (11.1%) were symptomatic and the remaining 16 (88.9%) were asymptomatic. In this study, newborn infants were considered symptomatic if central nervous system involvement such as micro‐ cephaly or ventricular dilatation was detected. SNHL was detected in 1 child (50%) with symptomatic infection and in 4 children (25%) with asymptomatic infection. Profound unilateral SNHL had developed in the child with symptomatic infection. In the 4 children with asymptomatic infection, the severity of SNHL varied from mild unilateral loss to profound bilateral loss. Of the 4 children, unilateral SNHL was identified in 3 (75%). Mild unilateral SNHL occurred in 2 children (66.7%), and profound unilateral loss occurred in 1 child (33.3%). Profound bilateral SNHL occurred in 1 child with asymptomatic infection. The unilateral hearing loss in case 1 was detected by a neonatal automatic auditory brainstem response (ABR) screener. SNHL in the other 3 children was detected by conventional ABR. Table 2 shows a summary of the findings from longitudinal audiological evaluations in the 5 children with asymptomatic congenital CMV infection. On subsequent audiological testing, delayed-onset SNHL was detected in 2 children who had passed the newborn hearing screening (NHS) test (1 bilateral and 1 unilateral). Two cases (40%) had progressive hearing loss and 2 (40%) had improvement of hearing loss from the initial abnormal ABR (profound unilateral loss and profound bilateral loss, respectively).


ABR: auditory brainstem response. This table is cited from reference [11].

Thus, the incidence of asymptomatic CMV infection and resulting SNHL may be higher, making it the leading cause of SNHL in children. Treatment of children with congenital CMV infection can prevent late-onset SNHL and/or deterioration of SNHL during early childhood. Cochlear implantation is also effective for the development of speech perception and auditory skills for deaf children with congenital CMV infection. Therefore, early identification of

**2. Epidemiology of hearing-impaired children with congenital CMV**

ase chain reaction (PCR) analysis of urine. Follow-up was conducted in these cases.

The symptoms at birth and sequelae observed during the first 6 months of life in the 18 children with congenital CMV infection are shown in Table 1. Among these infants, 2 children (11.1%) were symptomatic and the remaining 16 (88.9%) were asymptomatic. In this study, newborn infants were considered symptomatic if central nervous system involvement such as micro‐ cephaly or ventricular dilatation was detected. SNHL was detected in 1 child (50%) with symptomatic infection and in 4 children (25%) with asymptomatic infection. Profound unilateral SNHL had developed in the child with symptomatic infection. In the 4 children with asymptomatic infection, the severity of SNHL varied from mild unilateral loss to profound bilateral loss. Of the 4 children, unilateral SNHL was identified in 3 (75%). Mild unilateral SNHL occurred in 2 children (66.7%), and profound unilateral loss occurred in 1 child (33.3%). Profound bilateral SNHL occurred in 1 child with asymptomatic infection. The unilateral hearing loss in case 1 was detected by a neonatal automatic auditory brainstem response (ABR) screener. SNHL in the other 3 children was detected by conventional ABR. Table 2 shows a summary of the findings from longitudinal audiological evaluations in the 5 children with asymptomatic congenital CMV infection. On subsequent audiological testing, delayed-onset SNHL was detected in 2 children who had passed the newborn hearing screening (NHS) test (1 bilateral and 1 unilateral). Two cases (40%) had progressive hearing loss and 2 (40%) had

Of the 12,599 pregnant women included in a prospective study [13] conducted where from June 1996 to December 2003, maternal ages were as follows: <20 years, 1.6%; 20–24 years, 14.7%; 25–29 years, 41.4%; 30–34 years, 28.6%; 35–39 years, 7.9%; and >40 years, 0.8%. The annual seropositivity rate decreased over the 8-year study period, particularly during the last 4 years. The seropositivity rate of CMV immunoglobulin G (IgG) antibody was 75.3% in the sample as a whole. The seronegativity rate was 23.6%, and the percentage of cases borderline positive for IgG antibody was 1%. The seronegativity rate of CMV IgM antibody was 94.8% in the sample as a whole. The seropositivity rate was 2.2%, and 3% of cases were borderline positive for CMV IgM antibody. During the study period, in the cases positive for IgM antibody (n = 146), borderline positive for IgM antibody (n = 73), and borderline positive for IgG antibody (n = 14) and in cases with seroconversion of IgG antibody (n = 3), neonatal urine was analyzed for CMV DNA. Seroconversion of CMV IgG antibody occurred in 0.32% of the 929 cases negative for IgG antibody. Congenital CMV infection was identified in 18 infants by polymer‐

congenital CMV infection is very important.

2 Manifestations of Cytomegalovirus Infection

**infection**

**Table 1.** Initial symptoms and audiologic results during the first 6 months of life in 18 children with congenital CMV infection.


SNHL: sensorineural hearing loss. This table is cited from reference [11].

**Table 2.** Results of longitudinal audiologic examinations in 5 children with SNHL caused by asymptomatic CMV infection.

In this prospective study, the rates of delayed-onset SNHL, progressive SNHL, and improve‐ ment of SNHL were 12%, 40%, and 40%, respectively. Although a low rate of fetal CMV infection was observed, the results of the present study regarding the rate of SNHL are in accordance with the findings of those previous studies. The prevalence of congenital CMV infection is affected by the socioeconomic and geographic differences, but it seems to be no differences on characteristics of hearing loss induced by congenital CMV infection.

was defined as a decrease in hearing of ≥10 dB at 1 or more frequencies. Fluctuating hearing loss was defined as a decrease in hearing of >10 dB followed by an improvement of >10 dB at 1 or more frequencies. To analyze congenital CMV infection, CMV DNA quantitative PCR (qPCR) analysis was performed. Prior to qPCR analysis, total DNA, including genomic DNA and CMV DNA, was extracted from preserved dried umbilical cords. The results of this study revealed that in 9.0% (12/134) of children, SNHL could be attributed to congenital CMV infection. CMV DNA from preserved umbilical cords was detected in 8.7% (4/46) of children with bilateral SNHL and 9.1% (8/88) of those with unilateral SNHL. Congenital CMV infection caused bilateral severe-to-profound SNHL, bilateral mild-to-moderate SNHL, unilateral severe-to-profound SNHL, and unilateral mild-to-moderate SNHL in 14.3% (4/28), 0% (0/18), 9.6% (7/73), and 6.7% (1/15) of hearing-impaired children, respectively. This study also revealed that both congenital and late-onset SNHL could be caused by congenital CMV

**Hearing loss Gender Hearing level Severe-profound HL Mild-moderate HL**

(75.4%)

28 (20.9%)

72 (54.5%)

Table 4 shows the clinical characteristics of 12 children in whom CMV DNA was identified. Of these 12 children, bilateral SNHL was detected in 4 and unilateral SNHL in 8. All 4 children with bilateral SNHL had late-onset profound SNHL. Hearing fluctuation and PASS at the NHS test were confirmed in 3 children (75%). Of the 8 children with unilateral SNHL, detectable defects were confirmed in 2 children. Hearing fluctuation was detected in only 1 child (12.5%).

Retrospective diagnosis of congenital CMV infection is important to improve our understand‐ ing of the etiology of pediatric SNHL. In previous reports (Table 5), the frequency of congenital CMV infection in children with bilateral SNHL has varied from 3% to 36% because of variations in parameters (number of subjects, severity of SNHL) and methods [CMV IgM testing, DNA urinalysis, DNA from dried blood spots (DBS) in Guthrie cards] [19-24]. In 2 Japanese studies based on the retrospective diagnostic method of analysis of preserved dried umbilical cords, congenital CMV infection was detected in 10%–12% of children with bilateral SNHL [25, 26];

M: male, F: female. R: right, L: left. B: better ear, W: worse ear. This table is cited from reference [16].

No inner ear anomaly was found in any of the 8 children with unilateral SNHL.

**Table 3.** Summary of characteristics of children with bilateral or unilateral hearing loss.

M: 70, F: 64 101

71.7 dB [L]

13.6 dB (B)

M: 31, F: 15 71.8 dB [R]

M: 39, F: 49 89.5 dB (W)

HL: hearing loss. Diagnostic age: age diagnosed as hearing loss.

**(n) (dB) n Diagnostic age n Diagnostic age**

34.4±34.7 mo 33

16.6±19.9 mo 18

41.2±36.6 mo 15

(24.6%)

Hearing Loss in Children with Congenital Cytomegalovirus Infection

http://dx.doi.org/10.5772/56160

5

(13.4%)

(11.2%)

48.8±38.7 mo

11.1±39.1 mo

40.3±36.8 mo

infection.

Total (N=134)

Bilateral HL (N=46)

Unilateral HL (N=88)

Because they develop later, both delayed-onset and progressive hearing loss frequently remain undiagnosed during universal newborn hearing screening (NHS) test [7, 10]. The 1994 Joint Committee on Infant Hearing [14] pointed out that additional hearing evaluations after universal NHS are required to detect delayed-onset hearing loss. Combined neonatal screening for CMV infection and repeated auditory evaluation should be considered, particularly for children with asymptomatic congenital CMV infection. Counseling of pregnant women on prevention of CMV infection is also important.

#### **2.1. Retrospective study of congenital CMV infection**

Hearing loss in children with congenital CMV infection often presents at birth; however, in many instances, it may develop after months or even years. One report stated that children with normal hearing at 6 months of age develop hearing loss at a rate of approximately 1% per year; the cumulative risk of late-onset hearing loss is substantial (6.9%) in a population of in‐ fants with asymptomatic congenital CMV infection [15]. Speech is often delayed in children with bilateral hearing loss. For cases of severe bilateral SNHL, Ogawa et al. [16] reported that congenital CMV infection could be diagnosed through the detection of CMV DNA in the dried umbilical cord. In addition, genetic defects (particularly those related to *GJB2*) were identified in 15% and 30% of the children, respectively. However, the etiology of pediatric SNHL, in‐ cluding mild to moderate and unilateral SNHL, remains uncertain. In a study of congenital CMV infection retrospectively diagnosed by the detection of CMV DNA extracted from dried umbilical cord specimens, the prevalence of CMV in children with unilateral or bilateral SNHL was investigated. In many of these cases, SNHL developed several months or even years after birth.

In total, 134 patients (70 males and 64 females) with bilateral (n = 46; 34.3%) or unilateral (n = 88; 65.7%) SNHL were evaluated. These cases were referred to the Department of Otolaryng‐ ology, Shinshu University School of Medicine from May 2008 to September 2009 (Table 3) [17]. The age of these children ranged from 1 month to 138 months (mean age: 37.7 ± 36.2 months). In children with bilateral SNHL, both genetic testing for deafness and CMV DNA analysis were performed. For children with unilateral SNHL, CMV DNA analysis and genetic testing for gene mutations of *GJB2, Mitochondrial1555* were performed. Objective audiometric evaluation was performed for each patient using ABR and auditory steady-state evoked response systems (MASTER 580-NAVPRO; NIHON KOHDEN Co., Ltd, Tokyo, Japan). Behavioral audiological tests and/or pure-tone audiometry were also performed. Hearing levels were classified into 2 categories on the basis of the severity of hearing loss in the worse ear as severe (>70 dB) to profound (>90 dB) and mild (20–40 dB) to moderate (41–70 dB). Followup hearing assessments were performed at intervals of 6–12 months. Progressive hearing loss was defined as a decrease in hearing of ≥10 dB at 1 or more frequencies. Fluctuating hearing loss was defined as a decrease in hearing of >10 dB followed by an improvement of >10 dB at 1 or more frequencies. To analyze congenital CMV infection, CMV DNA quantitative PCR (qPCR) analysis was performed. Prior to qPCR analysis, total DNA, including genomic DNA and CMV DNA, was extracted from preserved dried umbilical cords. The results of this study revealed that in 9.0% (12/134) of children, SNHL could be attributed to congenital CMV infection. CMV DNA from preserved umbilical cords was detected in 8.7% (4/46) of children with bilateral SNHL and 9.1% (8/88) of those with unilateral SNHL. Congenital CMV infection caused bilateral severe-to-profound SNHL, bilateral mild-to-moderate SNHL, unilateral severe-to-profound SNHL, and unilateral mild-to-moderate SNHL in 14.3% (4/28), 0% (0/18), 9.6% (7/73), and 6.7% (1/15) of hearing-impaired children, respectively. This study also revealed that both congenital and late-onset SNHL could be caused by congenital CMV infection.


HL: hearing loss. Diagnostic age: age diagnosed as hearing loss.

In this prospective study, the rates of delayed-onset SNHL, progressive SNHL, and improve‐ ment of SNHL were 12%, 40%, and 40%, respectively. Although a low rate of fetal CMV infection was observed, the results of the present study regarding the rate of SNHL are in accordance with the findings of those previous studies. The prevalence of congenital CMV infection is affected by the socioeconomic and geographic differences, but it seems to be no

Because they develop later, both delayed-onset and progressive hearing loss frequently remain undiagnosed during universal newborn hearing screening (NHS) test [7, 10]. The 1994 Joint Committee on Infant Hearing [14] pointed out that additional hearing evaluations after universal NHS are required to detect delayed-onset hearing loss. Combined neonatal screening for CMV infection and repeated auditory evaluation should be considered, particularly for children with asymptomatic congenital CMV infection. Counseling of pregnant women on

Hearing loss in children with congenital CMV infection often presents at birth; however, in many instances, it may develop after months or even years. One report stated that children with normal hearing at 6 months of age develop hearing loss at a rate of approximately 1% per year; the cumulative risk of late-onset hearing loss is substantial (6.9%) in a population of in‐ fants with asymptomatic congenital CMV infection [15]. Speech is often delayed in children with bilateral hearing loss. For cases of severe bilateral SNHL, Ogawa et al. [16] reported that congenital CMV infection could be diagnosed through the detection of CMV DNA in the dried umbilical cord. In addition, genetic defects (particularly those related to *GJB2*) were identified in 15% and 30% of the children, respectively. However, the etiology of pediatric SNHL, in‐ cluding mild to moderate and unilateral SNHL, remains uncertain. In a study of congenital CMV infection retrospectively diagnosed by the detection of CMV DNA extracted from dried umbilical cord specimens, the prevalence of CMV in children with unilateral or bilateral SNHL was investigated. In many of these cases, SNHL developed several months or even

In total, 134 patients (70 males and 64 females) with bilateral (n = 46; 34.3%) or unilateral (n = 88; 65.7%) SNHL were evaluated. These cases were referred to the Department of Otolaryng‐ ology, Shinshu University School of Medicine from May 2008 to September 2009 (Table 3) [17]. The age of these children ranged from 1 month to 138 months (mean age: 37.7 ± 36.2 months). In children with bilateral SNHL, both genetic testing for deafness and CMV DNA analysis were performed. For children with unilateral SNHL, CMV DNA analysis and genetic testing for gene mutations of *GJB2, Mitochondrial1555* were performed. Objective audiometric evaluation was performed for each patient using ABR and auditory steady-state evoked response systems (MASTER 580-NAVPRO; NIHON KOHDEN Co., Ltd, Tokyo, Japan). Behavioral audiological tests and/or pure-tone audiometry were also performed. Hearing levels were classified into 2 categories on the basis of the severity of hearing loss in the worse ear as severe (>70 dB) to profound (>90 dB) and mild (20–40 dB) to moderate (41–70 dB). Followup hearing assessments were performed at intervals of 6–12 months. Progressive hearing loss

differences on characteristics of hearing loss induced by congenital CMV infection.

prevention of CMV infection is also important.

4 Manifestations of Cytomegalovirus Infection

years after birth.

**2.1. Retrospective study of congenital CMV infection**

M: male, F: female. R: right, L: left. B: better ear, W: worse ear. This table is cited from reference [16].

**Table 3.** Summary of characteristics of children with bilateral or unilateral hearing loss.

Table 4 shows the clinical characteristics of 12 children in whom CMV DNA was identified. Of these 12 children, bilateral SNHL was detected in 4 and unilateral SNHL in 8. All 4 children with bilateral SNHL had late-onset profound SNHL. Hearing fluctuation and PASS at the NHS test were confirmed in 3 children (75%). Of the 8 children with unilateral SNHL, detectable defects were confirmed in 2 children. Hearing fluctuation was detected in only 1 child (12.5%). No inner ear anomaly was found in any of the 8 children with unilateral SNHL.

Retrospective diagnosis of congenital CMV infection is important to improve our understand‐ ing of the etiology of pediatric SNHL. In previous reports (Table 5), the frequency of congenital CMV infection in children with bilateral SNHL has varied from 3% to 36% because of variations in parameters (number of subjects, severity of SNHL) and methods [CMV IgM testing, DNA urinalysis, DNA from dried blood spots (DBS) in Guthrie cards] [19-24]. In 2 Japanese studies based on the retrospective diagnostic method of analysis of preserved dried umbilical cords, congenital CMV infection was detected in 10%–12% of children with bilateral SNHL [25, 26]; however, these studies included few subjects (10–26 cases). In children with unilateral SNHL, CMV DNA from preserved umbilical cords was detected in 9.1% (8/88). The frequency of congenital CMV infection was similar in children with unilateral and bilateral SNHL. It has been speculated that approximately 10% of SNHL in children is caused by congenital CMV infection. Few reports have examined the frequency of congenital CMV infection using retrospective diagnostic methods in children with unilateral SNHL. However, using the CMV DNA detection method, 25% (1/4) [16] and 19% (8/42) [19] of children with unilateral SNHL were diagnosed with congenital CMV infection.


and CMV DNA positivity were detected in 32.1% (9/28) and 14.3% (4/28) of patients, respec‐ tively [17]. The diagnostic rate has been concluded to be 46.4% (13/28). If analysis of CMV DNA from preserved dried umbilical cords could be combined with genetic testing for deafness, approximately 50% of cases of bilateral severe-to-profound hearing loss in children could be

NR: not reported. NHS: newborn hearing screening. DBS: dried blood spot. UC: umbilical cord. qPCR: quantitative PCR.

HL: hearing level. SNHL: sensorineural hearing loss. Re.: republic. This table is cited from reference [16].

**Table 5.** List of previous reports on children with congenital CMV nfection.

**CMV positive rate Diagnostic**

Hearing Loss in Children with Congenital Cytomegalovirus Infection

**Total Bilateral Unilateral**

Barbi et al. [19] 2003 > 40 dBHL 9/79 (11.4%) 1/37 (2.7%) 8/42 (19%) DBS, qPCR Italy Ogawa et al. [16] 2007 > 20dB, nonsyndromic SNHL 10/67 (10.5%) 9/63 (14.3%) 1/4 (25%) US, PCR Japan Samileh et al. [21] 2008 > 40 dBHL 33/95 (34.7%) NR/75 NR/20 Cerologic test Iran Stehel et al. [22] 2008 NHS refer 16/256 (6%) 16/256 (6%) NR DNA from urine USA Walter et al. [43] 2008 unexplained SNHL 8/35 (22.9%) NR NR DSS, qPCR UK Mizuno et al. [44] 2008 only bilateral 3/45 (6.7%) 3/45 (6.7%) 0 UC, qPCR Japan

Jakubikova et al. [20] 2009 > 60 dBHL, NHS refer 4/71 (5.6%) 4/55 (7.3%) 0/16 (0%) Cerologic test Slovak Re. Boudewyns et al. [45] 2009 NHS refer, > 20 dB 4/55 (7.3%) NR NR DBS, qPCR Belgium

Choi et al. [18] 2009 NHS refer 13/479 (2.7%) 13/479 (2.7%) NR DBS, qPCR USA Tagawa et al. [26] 2009 > 70 dB, deaf school children 3/26 (11.5%) 3/26 (11.5%) 0 (0%) UC, qPCR Japan Kimani et al. [46] 2010 NHS refer 11/109 (10.1%) 8/92 (8.8%) 3/17 (17.6%) DBS, qPCR USA Adachi et al. [47] 2010 NHS refer, >35dB, bilateral 13/77 (17%) 13/77 (17%) 0 US, qPCR Japan

**methods**

http://dx.doi.org/10.5772/56160

**Country**

7

Congenital CMV infection is also often diagnosed by detecting CMV DNA in urine within the first 2 weeks of life and serological testing for CMV-specific IgM antibody from mother and child [28]. In recent years, the detection of CMV DNA by retrospective methods has been more valuable not only in diagnosing congenital CMV infection during later stages of life but also in identifying children at highest risk of late-onset and progressive SNHL. Some reports have stated that DBS stored on Guthrie cards has been used for the retrospective diagnosis of congenital CMV infections [18, 29]. Similarly, preserved umbilical cords have been recently used in Japan [25, 26, 30]. The sensitivity varies widely depending on the DNA extraction method in the DBS case. Some investigators have reported sensitivities of 71%–100% and specificities of 99%–100% [19, 29]. In this study, the qPCR method and preserved umbilical

cords were used because they were useful for more accurate detection of CMV DNA.

detected.

**Reference Year Subjects**

F: female, M: male. Mo: month. HL: hearing loss. R: right, L: left. NHS: newborn hearing screening. Diagnostic age: age diagnosed as hearing loss. This table is cited from reference [16].

**Table 4.** Clinical data of CMV DNA-positive children

#### **2.2. Genetic hearing loss and congenital CMV infection**

Genetic testing for deafness has become valuable for precise diagnosis of hearing loss. The most frequently implicated gene in nonsyndromic hearing loss is *GJB2*, the most prevalent gene responsible for congenital hearing loss worldwide. *GJB2, SLC26A4, CDH23*, and mito‐ chondrial 12s ribosomal RNA (rRNA) are the other major genes that cause hearing loss in Japan. One study stated that genetic mutations were responsible for deafness in 40%–45% of children with congenital hearing loss [27]. In our study [17], 10 gene mutations associated with deafness (*GJB2*, n = 7; *SLC26A4*, n = 3) were identified in 21.7% (10/46) of children with bilateral SNHL. In children with bilateral severe-to-profound SNHL, gene mutations causing deafness


HL: hearing level. SNHL: sensorineural hearing loss. Re.: republic. This table is cited from reference [16].

**Table 5.** List of previous reports on children with congenital CMV nfection.

however, these studies included few subjects (10–26 cases). In children with unilateral SNHL, CMV DNA from preserved umbilical cords was detected in 9.1% (8/88). The frequency of congenital CMV infection was similar in children with unilateral and bilateral SNHL. It has been speculated that approximately 10% of SNHL in children is caused by congenital CMV infection. Few reports have examined the frequency of congenital CMV infection using retrospective diagnostic methods in children with unilateral SNHL. However, using the CMV DNA detection method, 25% (1/4) [16] and 19% (8/42) [19] of children with unilateral SNHL

**Unilateral Severity Average HL**

**(R/L: dB)**

**Onset NHS**

were diagnosed with congenital CMV infection.

**Bilateral**/

 F 60 mo Bilateral Profound 87.5/108.8 Late Pass F 52 mo Bilateral Profound 87.5/110.0 Late Pass M 50 mo Bilateral Profound 100.0/100.0 Late Pass M 62 mo Bilateral Profound 110.0/46.3 Likely late −

5 M 6 mo Unilateral Profound 32.5/103.8 Congenital Refer (L)

 M 65 mo Unilateral Profound 107.5/17.5 Unknown − M 50 mo Unilateral Profound 6.3/100.0 Unknown − F 98 mo Unilateral Profound 110.0/15.0 Unknown − F 55 mo Unilateral Profound 15.0/92.5 Late Pass F 2 mo Unilateral Profound 90.0/18.3 Congenital Refer (R)

11 M 80 mo Unilateral Severe 13.3/70.0 Unknown − 12 F 44 mo Unilateral Moderate 15.0/58.3 Late Pass

Genetic testing for deafness has become valuable for precise diagnosis of hearing loss. The most frequently implicated gene in nonsyndromic hearing loss is *GJB2*, the most prevalent gene responsible for congenital hearing loss worldwide. *GJB2, SLC26A4, CDH23*, and mito‐ chondrial 12s ribosomal RNA (rRNA) are the other major genes that cause hearing loss in Japan. One study stated that genetic mutations were responsible for deafness in 40%–45% of children with congenital hearing loss [27]. In our study [17], 10 gene mutations associated with deafness (*GJB2*, n = 7; *SLC26A4*, n = 3) were identified in 21.7% (10/46) of children with bilateral SNHL. In children with bilateral severe-to-profound SNHL, gene mutations causing deafness

F: female, M: male. Mo: month. HL: hearing loss. R: right, L: left. NHS: newborn hearing screening.

Diagnostic age: age diagnosed as hearing loss. This table is cited from reference [16].

**2.2. Genetic hearing loss and congenital CMV infection**

**Table 4.** Clinical data of CMV DNA-positive children

**Case no. Sex Diagnostic age**

6 Manifestations of Cytomegalovirus Infection

and CMV DNA positivity were detected in 32.1% (9/28) and 14.3% (4/28) of patients, respec‐ tively [17]. The diagnostic rate has been concluded to be 46.4% (13/28). If analysis of CMV DNA from preserved dried umbilical cords could be combined with genetic testing for deafness, approximately 50% of cases of bilateral severe-to-profound hearing loss in children could be detected.

Congenital CMV infection is also often diagnosed by detecting CMV DNA in urine within the first 2 weeks of life and serological testing for CMV-specific IgM antibody from mother and child [28]. In recent years, the detection of CMV DNA by retrospective methods has been more valuable not only in diagnosing congenital CMV infection during later stages of life but also in identifying children at highest risk of late-onset and progressive SNHL. Some reports have stated that DBS stored on Guthrie cards has been used for the retrospective diagnosis of congenital CMV infections [18, 29]. Similarly, preserved umbilical cords have been recently used in Japan [25, 26, 30]. The sensitivity varies widely depending on the DNA extraction method in the DBS case. Some investigators have reported sensitivities of 71%–100% and specificities of 99%–100% [19, 29]. In this study, the qPCR method and preserved umbilical cords were used because they were useful for more accurate detection of CMV DNA.

#### **3. Diagnosis of congenital CMV infection**

#### **3.1. Detection methods**

The gold standard for diagnosis of congenital CMV infection is isolation of the virus from urine or saliva in the first 2 weeks of life. However, asymptomatic congenital CMV infection in children who develop SNHL after the first 2 weeks following birth cannot be diagnosed on the basis of viral isolation from urine or saliva. Detection of CMV DNA in infant blood or the umbilical cord using PCR assays is a more feasible method for identifying children with lateonset SNHL. The method involves analysis of blood stored as DBS on Guthrie cards. In Japanese culture, the dried umbilical cord is generally stored at home as a memento of the birth. These specimens are suitable for retrospective diagnosis of congenital CMV infection. The sensitivity varied widely depending on the DNA extraction method from DBS on Guthrie cards. Some investigators reported sensitivities of 71-100% and specificities of 99-100% [19, 29]. The qPCR method and dried umbilical cord could be useful for more precise detection of CMV DNA.

formed using the following primers and TaqMan® probe: GJB2-2F: 5′-ACGTCCACGT‐ TAGGATGAGG-3′, GJB2-2: 5′-GTATGTGGCGCTTCTCTCGT-3′, and GJB2-2 TaqMan probe: 5′-FAM- AACCTGTGCACCACAGCGCC -TAMRA-3′. The initial preheating steps were performed for 2 min at 50°C and 10 min at 95°C. Following this, qPCR was per‐ formed for 43 cycles of 15 s at 95°C and 60 s at 60°C. After qPCR analysis, relative CMV concentrations in each sample were evaluated as ΔCt (delta cycle threshold), which was calculated by determining the threshold cycle of CMV qPCR minus that of *GJB2* qPCR.

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9

The invader assay described by Abe [32] was used for genetic testing for deafness.

**4.1. Cochlear implantation in children deafened by symptomatic CMV infection**

**4.2. Cochlear implantation in children deafened by asymptomatic CMV infection**

The effectiveness of cochlear implantation in children deafened as a result of symptomatic congenital CMV infection has been evaluated by various groups, but there are only limited outcome data for deaf children with asymptomatic CMV infection. Children with asympto‐ matic congenital CMV infection have a better prognosis than symptomatic children, but it is difficult to evaluate the SNHL because children with asymptomatic congenital CMV infection

Cochlear implantation for the correction of congenital deafness is an effective way to ensure the development of speech recognition. Cochlear implantation in children deafened by symptomatic CMV infection has been reported [33, 34]. The prognosis of children with symptomatic CMV infection is worse than that of those with asymptomatic CMV infection with regard to cognitive and neurological development. It has been suggested that cochlear implantation should be contraindicated for infants with symptomatic CMV infection and deafness because they are less likely to develop spoken language [35]. In contrast, other reports [33, 34] have suggested that cochlear implantation may improve quality of life, even if progress is slower or lesser than that expected in congenitally deaf children not infected with CMV. Pyman et al. [35] suggested that the prognosis in terms of linguistic outcome after cochlear implantation is poorer for CMV-infected deaf children than for other congenitally deaf children because of coexisting central disorders. Wide variation in speech perception and intelligibility after cochlear implantation has also been reported in children deafened by symptomatic CMV infection [33]. In that report, poor development in these areas was observed in 50% of children with symptomatic CMV infection, whereas development similar to that in congenitally deaf children not infected with CMV was evident in 31% of children and devel‐ opment better than that in noninfected congenitally deaf children was evident in 19% of children. In addition, a recent study has shown that deafness caused by symptomatic congen‐ ital CMV infection associated with motor and cognitive delays is not a contraindication for cochlear implantation. Early diagnosis of hearing loss and subsequent cochlear implantation

**4. Treatment for hearing loss induced by**

is important for successful speech perception [34].

**congenital CMV infection**

#### **3.2. Serological method**

Diagnosis of symptomatic CMV infection is easier in children who display cognitive or neuromuscular abnormalities than in asymptomatic children with CMV infection. Without neonatal viral screening, the prevalence of SNHL caused by asymptomatic CMV infection remains undetermined. To diagnose primary CMV infection, a serological method has been used [31]. Pregnant women who test positive for CMV IgG seroconversion or CMV IgM antibody may transmit the virus to the fetus. Production of IgM antibody persists for 6–9 months [28]; therefore, a CMV IgM-positive result alone does not accurately predict the risk of fetal infection.

#### **3.3. Detection of CMV DNA from umbilical cord**

For the detection of congenital CMV infection, CMV DNA qPCR analysis was performed. Prior to qPCR analysis, total DNA, including genomic DNA and CMV DNA, was extract‐ ed from preserved dried umbilical cords. The procedure is as follows. Each 5-mm tissue section was incubated in a lysis buffer containing proteinase K and incubated overnight at 56°C. Total DNA was extracted using the DNeasy® Blood & Tissue Kit (Qiagen GmbH, Hilden, Germany), according to the manufacturer's instructions. The total amount of DNA was measured using the Qubit® Fluorometer with Quant-iT™ dsDNA BR Assay Kit (Life technologies-Invitrogen, Carlsbad, CA, USA). Total DNA (10 pg) was analyzed using the Step One Real-Time PCR System (Applied Biosystems, Foster City, CA, USA) and TaqMan® Universal Master Mix II (Applied Biosystems). The qPCR primers and TaqMan® probe used for CMV DNA qPCR analysis were as follows: US14-1F: 5′- ACGTCCACGTTAGGATGAGG-3′, US14-1R: 5′-GTATGTGGCGCTTCTCTCGT-3′, and US14-1 TaqMan probe: 5′-FAM- AACCTGTGCACCACAGCGCC -TAMRA-3′. To quantify the input DNA amount in each sample, qPCR of each genomic region was also per‐ formed using the following primers and TaqMan® probe: GJB2-2F: 5′-ACGTCCACGT‐ TAGGATGAGG-3′, GJB2-2: 5′-GTATGTGGCGCTTCTCTCGT-3′, and GJB2-2 TaqMan probe: 5′-FAM- AACCTGTGCACCACAGCGCC -TAMRA-3′. The initial preheating steps were performed for 2 min at 50°C and 10 min at 95°C. Following this, qPCR was per‐ formed for 43 cycles of 15 s at 95°C and 60 s at 60°C. After qPCR analysis, relative CMV concentrations in each sample were evaluated as ΔCt (delta cycle threshold), which was calculated by determining the threshold cycle of CMV qPCR minus that of *GJB2* qPCR. The invader assay described by Abe [32] was used for genetic testing for deafness.

### **4. Treatment for hearing loss induced by congenital CMV infection**

**3. Diagnosis of congenital CMV infection**

The gold standard for diagnosis of congenital CMV infection is isolation of the virus from urine or saliva in the first 2 weeks of life. However, asymptomatic congenital CMV infection in children who develop SNHL after the first 2 weeks following birth cannot be diagnosed on the basis of viral isolation from urine or saliva. Detection of CMV DNA in infant blood or the umbilical cord using PCR assays is a more feasible method for identifying children with lateonset SNHL. The method involves analysis of blood stored as DBS on Guthrie cards. In Japanese culture, the dried umbilical cord is generally stored at home as a memento of the birth. These specimens are suitable for retrospective diagnosis of congenital CMV infection. The sensitivity varied widely depending on the DNA extraction method from DBS on Guthrie cards. Some investigators reported sensitivities of 71-100% and specificities of 99-100% [19, 29]. The qPCR method and dried umbilical cord could be useful for more precise detection of

Diagnosis of symptomatic CMV infection is easier in children who display cognitive or neuromuscular abnormalities than in asymptomatic children with CMV infection. Without neonatal viral screening, the prevalence of SNHL caused by asymptomatic CMV infection remains undetermined. To diagnose primary CMV infection, a serological method has been used [31]. Pregnant women who test positive for CMV IgG seroconversion or CMV IgM antibody may transmit the virus to the fetus. Production of IgM antibody persists for 6–9 months [28]; therefore, a CMV IgM-positive result alone does not accurately predict the risk

For the detection of congenital CMV infection, CMV DNA qPCR analysis was performed. Prior to qPCR analysis, total DNA, including genomic DNA and CMV DNA, was extract‐ ed from preserved dried umbilical cords. The procedure is as follows. Each 5-mm tissue section was incubated in a lysis buffer containing proteinase K and incubated overnight at 56°C. Total DNA was extracted using the DNeasy® Blood & Tissue Kit (Qiagen GmbH, Hilden, Germany), according to the manufacturer's instructions. The total amount of DNA was measured using the Qubit® Fluorometer with Quant-iT™ dsDNA BR Assay Kit (Life technologies-Invitrogen, Carlsbad, CA, USA). Total DNA (10 pg) was analyzed using the Step One Real-Time PCR System (Applied Biosystems, Foster City, CA, USA) and TaqMan® Universal Master Mix II (Applied Biosystems). The qPCR primers and TaqMan® probe used for CMV DNA qPCR analysis were as follows: US14-1F: 5′- ACGTCCACGTTAGGATGAGG-3′, US14-1R: 5′-GTATGTGGCGCTTCTCTCGT-3′, and US14-1 TaqMan probe: 5′-FAM- AACCTGTGCACCACAGCGCC -TAMRA-3′. To quantify the input DNA amount in each sample, qPCR of each genomic region was also per‐

**3.1. Detection methods**

8 Manifestations of Cytomegalovirus Infection

CMV DNA.

**3.2. Serological method**

of fetal infection.

**3.3. Detection of CMV DNA from umbilical cord**

#### **4.1. Cochlear implantation in children deafened by symptomatic CMV infection**

Cochlear implantation for the correction of congenital deafness is an effective way to ensure the development of speech recognition. Cochlear implantation in children deafened by symptomatic CMV infection has been reported [33, 34]. The prognosis of children with symptomatic CMV infection is worse than that of those with asymptomatic CMV infection with regard to cognitive and neurological development. It has been suggested that cochlear implantation should be contraindicated for infants with symptomatic CMV infection and deafness because they are less likely to develop spoken language [35]. In contrast, other reports [33, 34] have suggested that cochlear implantation may improve quality of life, even if progress is slower or lesser than that expected in congenitally deaf children not infected with CMV. Pyman et al. [35] suggested that the prognosis in terms of linguistic outcome after cochlear implantation is poorer for CMV-infected deaf children than for other congenitally deaf children because of coexisting central disorders. Wide variation in speech perception and intelligibility after cochlear implantation has also been reported in children deafened by symptomatic CMV infection [33]. In that report, poor development in these areas was observed in 50% of children with symptomatic CMV infection, whereas development similar to that in congenitally deaf children not infected with CMV was evident in 31% of children and devel‐ opment better than that in noninfected congenitally deaf children was evident in 19% of children. In addition, a recent study has shown that deafness caused by symptomatic congen‐ ital CMV infection associated with motor and cognitive delays is not a contraindication for cochlear implantation. Early diagnosis of hearing loss and subsequent cochlear implantation is important for successful speech perception [34].

#### **4.2. Cochlear implantation in children deafened by asymptomatic CMV infection**

The effectiveness of cochlear implantation in children deafened as a result of symptomatic congenital CMV infection has been evaluated by various groups, but there are only limited outcome data for deaf children with asymptomatic CMV infection. Children with asympto‐ matic congenital CMV infection have a better prognosis than symptomatic children, but it is difficult to evaluate the SNHL because children with asymptomatic congenital CMV infection are at risk of development of delayed onset SNHL and progressive SNHL. As a result, they are also at risk of late-onset learning difficulties and/or progressive learning difficulties.

**5. Conclusion**

Congenital CMV infection is a major cause of bilateral and unilateral SNHL in children. In total, 9.0% of SNHL cases of unknown causes (bilateral SNHL: 8.7%, unilateral SNHL: 9.1%) are attributed to congenital CMV infection. Screening tests such as the detection of CMV DNA from preserved dried umbilical cords and genetic testing are important for the detection of SNHL in children. Using this combined methodology, detection of the cause of SNHL is

Hearing Loss in Children with Congenital Cytomegalovirus Infection

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11

Cochlear implantation is effective to ensure the development of speech perception and auditory skills in deaf children with asymptomatic congenital CMV infection. No significant difference in growth of meaningful auditory integration was observed between the overall pediatric cochlear implant population not infected with CMV and that with asymptomatic CMV infection. Implementation of CMV screening models is important to prevent late-onset

These works were supported by grants for Research on Sensory and Communicative Disorders from Ministry of Health, Labour and Welfare and grants for Scientific Research (C) from

1 Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsu‐

2 Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto

[1] Hagay, Z. J, Biran, G, Ornoy, A, & Reece, E. A. Congenital cytomegalovirus infection: a long-standing problem still seeking a solution. Am J Obstet Gynecol (1996). , 174,

Ministry of Education, Culture, Sports, Science and Technology, Tokyo, Japan.

possible in approximately 50% of children with hearing loss.

SNHL and deterioration of hearing loss.

and Shin-ich Usami2\*

\*Address all correspondence to: usami@shinshu-u.ac.jp

**Acknowledgements**

**Author details**

Satoshi Iwasaki1

moto City, Japan

City, Japan

**References**

241-5.

A prospective study was conducted on deaf children with asymptomatic CMV infection to assess the development of speech perception and auditory skills. This study examined 2 deaf infants before and after cochlear implantation using the Infant/Toddler Meaningful Auditory Integration Scale (IT-MAIS) [36]. Vocalization behavior in case 1 was observed 6 months after implementation and showed slow improvement but finally overtook after 36 months. After 3 months of cochlear implant use, the 2 children responded to speech and environmental sounds in everyday situations and interpreted sounds in a meaningful way. They continued to improve at 36 months postoperatively. IT-MAIS scores in these 2 children were similar to the mean scores in the 5 congenitally deaf children without CMV infection. No difference was observed in the effect of early cochlear implantation for deafness induced by CMV infection between the groups of children. Another group reported that significant improvement in auditory and language skills could be achieved in cochlear implanted children with asymp‐ tomatic CMV infection, but they did not achieve the same levels of outcome as congenitally deaf children without CMV infection [37]. They found a wide variation in the outcome of cochlear implantation in these children and speculated that the variation is related to the degree of cognitive impairment. There are only a few studies available on outcomes of cochlear implanted children with asymptomatic CMV infection. Therefore, more studies will be needed to evaluate the effectiveness of cochlear implantation in these children.

#### **4.3. Treatment for hearing-impaired children with congenital CMV infection**

To prevent late-onset and/or deterioration of SNHL, treatment with intravenous ganciclovir (GCV) and/or oral valganciclovir (VGCV) has been recommended in children with sympto‐ matic congenital CMV disease involving the central nervous system [38-41]. In previous reports, treatment with intravenous GCV was initiated within the first 10–14 days of life for 2–6 weeks, and GCV doses ranged from 5 to 12 mg/kg twice daily. One report revealed that in 5 of 9 children with congenital CMV infection and SNHL, treatment with intravenous GCV induced improvement of SNHL in 2 children and prevented deterioration of SNHL in 5 children [38]. Another report revealed that in 4 of 6 children with congenital CMV infection and SNHL, treatment with intravenous GCV induced improvement of SNHL in 2 children and no deterioration of SNHL in 4 children during the 21-month observation period [39]. Im‐ provement of SNHL or maintenance of normal hearing was reported in 84% of children treated with intravenous GCV and 59% of untreated children. Deterioration of SNHL was reported in 21% of treated children and 68% of untreated children [40]. According to these reports, good results have been observed in the group of children treated with GCV. Treatment with intravenous GCV and oral VGCV can prevent the development of SNHL during an 18-month administration period [41]. Treatment with intravenous GCV has been investigated in hearingimpaired children with asymptomatic congenital CMV infection. No SNHL was found for 4 – 11 years in 12 children with asymptomatic congenital CMV infection treated with intravenous GCV, but SNHL developed in 2 of 11 untreated children [42]. Unfortunately there is no evidence for the efficacy of longer treatment with oral VGCV.

#### **5. Conclusion**

are at risk of development of delayed onset SNHL and progressive SNHL. As a result, they are also at risk of late-onset learning difficulties and/or progressive learning difficulties.

10 Manifestations of Cytomegalovirus Infection

A prospective study was conducted on deaf children with asymptomatic CMV infection to assess the development of speech perception and auditory skills. This study examined 2 deaf infants before and after cochlear implantation using the Infant/Toddler Meaningful Auditory Integration Scale (IT-MAIS) [36]. Vocalization behavior in case 1 was observed 6 months after implementation and showed slow improvement but finally overtook after 36 months. After 3 months of cochlear implant use, the 2 children responded to speech and environmental sounds in everyday situations and interpreted sounds in a meaningful way. They continued to improve at 36 months postoperatively. IT-MAIS scores in these 2 children were similar to the mean scores in the 5 congenitally deaf children without CMV infection. No difference was observed in the effect of early cochlear implantation for deafness induced by CMV infection between the groups of children. Another group reported that significant improvement in auditory and language skills could be achieved in cochlear implanted children with asymp‐ tomatic CMV infection, but they did not achieve the same levels of outcome as congenitally deaf children without CMV infection [37]. They found a wide variation in the outcome of cochlear implantation in these children and speculated that the variation is related to the degree of cognitive impairment. There are only a few studies available on outcomes of cochlear implanted children with asymptomatic CMV infection. Therefore, more studies will be needed

to evaluate the effectiveness of cochlear implantation in these children.

evidence for the efficacy of longer treatment with oral VGCV.

**4.3. Treatment for hearing-impaired children with congenital CMV infection**

To prevent late-onset and/or deterioration of SNHL, treatment with intravenous ganciclovir (GCV) and/or oral valganciclovir (VGCV) has been recommended in children with sympto‐ matic congenital CMV disease involving the central nervous system [38-41]. In previous reports, treatment with intravenous GCV was initiated within the first 10–14 days of life for 2–6 weeks, and GCV doses ranged from 5 to 12 mg/kg twice daily. One report revealed that in 5 of 9 children with congenital CMV infection and SNHL, treatment with intravenous GCV induced improvement of SNHL in 2 children and prevented deterioration of SNHL in 5 children [38]. Another report revealed that in 4 of 6 children with congenital CMV infection and SNHL, treatment with intravenous GCV induced improvement of SNHL in 2 children and no deterioration of SNHL in 4 children during the 21-month observation period [39]. Im‐ provement of SNHL or maintenance of normal hearing was reported in 84% of children treated with intravenous GCV and 59% of untreated children. Deterioration of SNHL was reported in 21% of treated children and 68% of untreated children [40]. According to these reports, good results have been observed in the group of children treated with GCV. Treatment with intravenous GCV and oral VGCV can prevent the development of SNHL during an 18-month administration period [41]. Treatment with intravenous GCV has been investigated in hearingimpaired children with asymptomatic congenital CMV infection. No SNHL was found for 4 – 11 years in 12 children with asymptomatic congenital CMV infection treated with intravenous GCV, but SNHL developed in 2 of 11 untreated children [42]. Unfortunately there is no

Congenital CMV infection is a major cause of bilateral and unilateral SNHL in children. In total, 9.0% of SNHL cases of unknown causes (bilateral SNHL: 8.7%, unilateral SNHL: 9.1%) are attributed to congenital CMV infection. Screening tests such as the detection of CMV DNA from preserved dried umbilical cords and genetic testing are important for the detection of SNHL in children. Using this combined methodology, detection of the cause of SNHL is possible in approximately 50% of children with hearing loss.

Cochlear implantation is effective to ensure the development of speech perception and auditory skills in deaf children with asymptomatic congenital CMV infection. No significant difference in growth of meaningful auditory integration was observed between the overall pediatric cochlear implant population not infected with CMV and that with asymptomatic CMV infection. Implementation of CMV screening models is important to prevent late-onset SNHL and deterioration of hearing loss.

#### **Acknowledgements**

These works were supported by grants for Research on Sensory and Communicative Disorders from Ministry of Health, Labour and Welfare and grants for Scientific Research (C) from Ministry of Education, Culture, Sports, Science and Technology, Tokyo, Japan.

#### **Author details**

Satoshi Iwasaki1 and Shin-ich Usami2\*

\*Address all correspondence to: usami@shinshu-u.ac.jp

1 Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsu‐ moto City, Japan

2 Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto City, Japan

#### **References**

[1] Hagay, Z. J, Biran, G, Ornoy, A, & Reece, E. A. Congenital cytomegalovirus infection: a long-standing problem still seeking a solution. Am J Obstet Gynecol (1996). , 174, 241-5.

[2] Stagno, S, Pass, R. F, Cloud, G, Britt, W. J, Henderson, R. E, Walton, P. D, et al. Pri‐ mary cytomegalovirus infection in pregnancy. Incidence, transmission to fetus, and clinical outcome. JAMA (1986). , 256, 1904-8.

[15] Rosenthal, L. S, Fowler, K. B, Boppana, S. B, Britt, W. J, Pass, R. F, Schmid, D. S, et al. Cytomegalovirus shedding and delayed sensorineural hearing loss: results from lon‐ gitudinal follow-up of children with congenital infection. Pediatr Infect Dis J (2009). ,

Hearing Loss in Children with Congenital Cytomegalovirus Infection

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13

[16] Ogawa, H, Suzutani, T, Baba, Y, Koyano, S, Nozawa, N, Ishibashi, K, et al. Etiology of severe sensorineural hearing loss in children: independent impact of congenital

cytomegalovirus infection and GJB2 mutations. J Infect Dis (2007). , 195, 782-8.

nosis using preserved umbilical cord. Acta Ololaryngol (2011). , 131, 976-82.

pass newborn hearing screening. Pediatr Infect Dis (2009). , 28, 1095-8.

[17] Furutate, S, Iwasaki, S, Nishio, S, Moteki, H, & Usami, S. Clinical profile of hearing loss in children with congenital cytpmegalovirus (CMV) infection: CMV DNA diag‐

[18] Choi, K. Y, Schimmenti, L. A, Jurek, A. M, Sharon, B, Daly, K, Khan, C, et al. Detec‐ tion of cytomegalovirus DNA in dried blood pots of Minnesota infants who do not

[19] Barbi M Binda SCaroppo S, Ambrosetti U, Corbetta C, Sergi P. A wider role for con‐ genital cytomegalovirus infection in sensorineural hearing loss. Pediatr Infect Dis J

[20] Jakubikova, J, Kabatova, Z, Pavlovcinova, G, & Profant, M. Newborn hearing screen‐ ing and strategy for early detection of hearing loss in infants. Int J Pediatr Otorhino‐

[21] Samileh, N, Ahmad, S, Mohammad, F, Framarz, M, Azardokht, T, & Jomeht, E. Role of cytomegalovirus in sensorineural hearing loss of children: a case-control study

[22] Stehel, EK, Shoup, AG, & Owen, . . Newborn hearing screening and detection of con‐

[23] Grosse, S. D, Ross, D. S, & Dollard, S. C. Congenital cytomegalovirus (CMV) infec‐ tion as a cause of permanent bilateral hearing loss: a quantitative assessment. J Clin

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[2] Stagno, S, Pass, R. F, Cloud, G, Britt, W. J, Henderson, R. E, Walton, P. D, et al. Pri‐ mary cytomegalovirus infection in pregnancy. Incidence, transmission to fetus, and

[3] Pass, R. F, Stagno, S, Myers, G. J, & Alford, C. A. Outcome of symptomatic congenital cytomegalovirus infection: results of long-term longitudinal follow-up. Pediatrics

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[10] Fowler, K. B, Dahle, A. J, Boppana, S. B, & Pass, R. F. Newborn hearing screening: will children with hearing loss caused by congenital cytomegalovirus infection be

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[13] Iwasaki, S, Yamashita, M, Maeda, M, Misawa, K, & Mineta, H. Audiological outcome of infants with congenital cytomegalovirus infection in a prospective study. Audiol

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[27] Usami, S, Wagatsuma, M, Fukuoka, H, Suzuki, H, Tsukada, K, Nishio, S, et al. The responsible genes in Japanese deafness patients and clinical application using Invad‐ er assay. Acta Otolaryingol (2008). , 128, 446-54.

[39] Kimberlin, D. W, Lin, C. Y, Sanchez, P. J, Demmler, G. J, Dankner, W, Shelton, M, et al. Effect of ganciclovir therapy on hearing in symptomatic congenital cytomegalovi‐ rus disease involving the cebtral nervous system: a randomized, controlled trial. J Pe‐

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[40] Kitajima, N, Sugaya, N, Futatani, T, Kanegane, H, Suzuki, C, Oshiro, M, et al. Ganci‐ clovir therapy for congenital cytomegalovirus infection in six infants. Pediatr Infect

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[42] Lackner, A, Acham, A, Alborno, T, Moser, M, Engele, H, Raggam, R. B, et al. Effect on hearing of ganciclovir therapy for asymptomatic congenital cytomegalovirus in‐

[43] Walter, S, Atkinson, C, Sharland, M, Rice, P, Raglan, E, Emery, V. C, et al. Congenital cytomegalovirus: association between dried blood spot viral load and hearing loss.

[44] Mizuno, T, Sugiura, S, Kimura, H, Ando, Y, Sone, M, Nishiyama, Y, et al. Detection of cytomegalovirus DNA in preserved umbilical cords from patients with sensori‐

[45] Boudewyns, A, Declau, F, Smets, K, Ursi, D, & Eyskens, F. Van den Ende J, et al. Cy‐ tomegalovirus DNA detection in Guthrie cards: role in the giagnostic work-up of

[46] Kimani, J. W, Buchman, C. A, Booker, J. K, Huang, B. Y, Castillo, M, Powell, C. M, et al. Seonsorineural hearing loss in a pediatric population: association of cobgenital cy‐ tomegalovirus infection with intracranial abnormalities. Arch Otolaryngol Head

[47] Adachi, N, Ito, K, Sakata, H, & Yamasoba, T. Etiology and one-year follow-up results of hearing loss identified by screening of newborn hearing in Japan. Otolaryngol

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[28] Genser, B, Truschnig-wilders, M, Stunzner, D, Landini, M. D, & Halwachs-baumann, G. Evaluation of five commercial enzyme immunoassays for the detection of human cytomegalovirus-specific IgM antibodies in the absence of a commercially available

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[30] Koyano, S, Inoue, N, Nagamori, T, Yan, H, Asanuma, H, Yagyu, K, et al. Dried um‐ bilical cords in the retrospective diagnosis of congenital cytomegalovirus infection as

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[32] Abe, S, Yamaguchi, T, & Usami, S. Application of deafness diagnostic screening pan‐ el based on deafness mutation/gene database using invader assay. Genet Test

[33] Ramirez Inscoe JMNikolopoulos TP. Cochlear implantation in children deafened by cytomegalovirus: speech perception and speech intelligibility outcomes. Otol Neuro‐

[34] Lee, D. J, Lustig, L, Sampson, M, Chinnici, J, & Niparko, J. K. Effects of cytomegalovi‐ rus (CMV) related deafness on pediatric cochlear implant outcomes. Otolaryngol

[35] Pyman, B, & Blamey, P. Lacy P Clark G, Dowell R. The development of speech per‐ ception in children using cochlear implants: effects of etiologic factors and delayed

[36] Iwasaki, S, Nakanishi, H, Misawa, K, Tanigawa, T, & Mizuta, K. Cochlear implant in children with asymptomatic congenital cytomegalovirus infection. Audiol Neurotol

[37] Malik, V, Bruce, I. A, Broomfield, S. J, Henderson, L, Green, K, & Ramsden, R. T. Outcome of cochlear implantation in asymptomatic congenital cytomegalovirus

[38] Michaels, M. G, Greenberg, D. P, Sabo, D. L, & Wald, E. R. Treatment of children with congenital cytomegalovirus infection with gancicolovir. Pediatr Infect Dis J

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**Chapter 2**

**Human Cytomegalovirus (HCMV) Infection in Sub-**

There have been over 25 published studies which present HCMV IgG seroprevalence data for sub-Saharan Africa patient groups and cohorts of healthy blood donors (Table 1). Up to eight different serology assays were used and older pre-ELISA methods might have slightly underestimated prevalence [1]. Antibodies to HCMV are generally present in high titres in seropositive individuals, so the use of different assays is unlikely to have had a major effect [2]. Hence, comparing these studies is primarily confounded by the diverse range of patient groups tested. Few studies stratify by age, or they do so using different groupings. Most of the studies use convenience samples, which do not provide accurate population-based estimates of

The most striking observation is that HCMV primary infection appears to be endemic in young infants. A population-based study in Zambia of 460 healthy infants showed 83% HCMV seroprevalence by 18 months of age [3](Table 1). This backs up much older studies from the Gambia [4] and Nigeria [5]. This differs from the results of larger studies in the USA (n = 30,000) where HCMV seroprevalence ranges from 36% in 6–11 year-olds to 91% in those over 80 years old. The cumulative incidence of HCMV primary infection was ~1% per year from adolescence [6]. In the USA, non-white ethnicity and lower socioeconomic status (SES) were linked with 10-30 percentage point increases in seroprevalence [7]. A study of over 20,000 women in the U.K attending antenatal clinics found similar results, with increasing parity also being linked

> © 2013 Bates et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

> © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

distribution, and reproduction in any medium, provided the original work is properly cited.

and reproduction in any medium, provided the original work is properly cited.

**Saharan Africa**

Alimuddin Zumla

**1. Introduction**

prevalence.

*1.1.1. HCMV seroprevalence*

http://dx.doi.org/10.5772/54907

Matthew Bates, Kunda Musonda and

Additional information is available at the end of the chapter

**1.1. HCMV epidemiology in Sub-Saharan Africa**

## **Human Cytomegalovirus (HCMV) Infection in Sub-Saharan Africa**

Matthew Bates, Kunda Musonda and Alimuddin Zumla

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/54907

#### **1. Introduction**

#### **1.1. HCMV epidemiology in Sub-Saharan Africa**

#### *1.1.1. HCMV seroprevalence*

There have been over 25 published studies which present HCMV IgG seroprevalence data for sub-Saharan Africa patient groups and cohorts of healthy blood donors (Table 1). Up to eight different serology assays were used and older pre-ELISA methods might have slightly underestimated prevalence [1]. Antibodies to HCMV are generally present in high titres in seropositive individuals, so the use of different assays is unlikely to have had a major effect [2]. Hence, comparing these studies is primarily confounded by the diverse range of patient groups tested. Few studies stratify by age, or they do so using different groupings. Most of the studies use convenience samples, which do not provide accurate population-based estimates of prevalence.

The most striking observation is that HCMV primary infection appears to be endemic in young infants. A population-based study in Zambia of 460 healthy infants showed 83% HCMV seroprevalence by 18 months of age [3](Table 1). This backs up much older studies from the Gambia [4] and Nigeria [5]. This differs from the results of larger studies in the USA (n = 30,000) where HCMV seroprevalence ranges from 36% in 6–11 year-olds to 91% in those over 80 years old. The cumulative incidence of HCMV primary infection was ~1% per year from adolescence [6]. In the USA, non-white ethnicity and lower socioeconomic status (SES) were linked with 10-30 percentage point increases in seroprevalence [7]. A study of over 20,000 women in the U.K attending antenatal clinics found similar results, with increasing parity also being linked

© 2013 Bates et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

with increased HCMV seroprevalence. This supports the notion that seronegative adult women contract primary HCMV infection from children who are shedding virus [8]. Figure 1 presents a model for cumulative HCMV seroprevalence by age with respect to SES, showing more rapid uptake in low SES communities, and delayed uptake in high SES communities. Conversely an Israeli study found the effect of ethnicity persisted even when corrected for gender, education and SES [9], and high HCMV seroprevalence has been described in populations with high SES groups [10, 11].

1

19

Whilst lower SES may be the main driver for endemic infant HCMV primary infection in sub-Saharan Africa, this is not the whole story. What factors, attributable to low SES, facilitate earlier HCMV transmission? HCMV is primarily transmitted through body fluids, being shed in urine, saliva [12, 13] and breast milk [14, 15]. In Nigeria, over-crowding was significantly associated with being HCMV seropositive, but source of drinking water, place of abode and type of toilet facility were not [16]. Some individuals remain seronegative into old age - even in sub-Saharan Africa where most people are infected in infancy. Human genetic variations may block or impair HCMV primary infection, as is seen with the CCR5 ∆32 mutation and HIV [17]. HCMV seronegative individuals have increased longevity, possibly linked with reduced clonal expansion of CD8 T cells and a larger reservoir of circulating naive T cells [18, 19] so early childhood primary infection with HCMV in sub-Saharan Africa may have profound effects. There is evidence linking early HCMV infections in sub-Saharan Africa with impaired physical and mental development [3], analogous to the known developmental CNS defects (hearing loss, mental retardation, cerebral palsy, seizures, chorioretinitis) caused by congenital HCMV infection [20, 21].

**Country (City) HCMV IgG seroprevalence\* Study population N= Assay Reference**

Nigeria (Ibadan) 55.0% Adult healthy blood donors 110 Compliment fixation [22]

Mali (Bamako) 58.0% Adult healthy HIV-ve blood donors 100 ELISA (Platelia® Sanofi Pasteur) [23]

Tanzania (Dar Es Salaam) 66.9% Adult inpatients with STDs (HIV-ve) 158 Passive latex agglutination (CMV-scan card) [24]

Ghana (Accra) 77.6% Adult healthy HIV-ve blood donors 3275 ELISA IgG; Diamedix Corporation, USA [25]

Burkina Faso (Bobo Dioulasso) 82.0% Adult healthy HIV-ve blood donors 28 ELISA (Platelia® Sanofi Pasteur) [26]

Ghana (Kumasi) 94.3% Health Blood Donors 112 Platella TM CMV IgG (Bio-Rad) [27]

Somalia (Mogadishu) 96% Healthy adult makes 102 unspecified [28]

Somalia (Mogadishu) 96% Adult males attending STD clinic 101 unspecified [28]

Kenya (Nairobi) 97.0% Adult healthy blood donors (1.3% HIV+) 400 unspecified [29]

Mali (Bamako) 71.0% HIV+ Adults 100 ELISA (Platelia® Sanofi Pasteur) [23]

Tanzania (Dar Es Salaam) 72.3% Adult inpatients with STDs (HIV+ve) 65 Passive latex agglutination (CMV-scan card) [24]

Ghana (Kumasi) 92.7% Asymptomatic HIV+ Adults 55 Platella TM CMV IgG (Bio-Rad) [27]

Botswana (Gaborone) 96.3% Asymptomatic HIV+ Adults 43 [30]

Ghana (Accra) 59.2% AIDS patients 250 ELISA IgG; Diamedix Corporation, USA [25]

Mali (Bamako) 89.0% AIDS patients 100 ELISA (Platelia® Sanofi Pasteur) [23]

Tanzania (Dar Es Salaam) 90.7% AIDS patients 43 Passive latex agglutination (CMV-scan card) [24]

Ghana (Kumasi) 98.3% AIDS patients 239 Platella TM CMV IgG (Bio-Rad) [27]

Burkina Faso (Bobo Dioulasso) 100% AIDS patients 36 ELISA (Platelia® Sanofi Pasteur) [26]

Tanzania (Dar Es Salaam) 60.6% HIV-ve pregnant women 127 Passive latex agglutination (CMV-scan card) [24]

Tanzania (Dar Es Salaam) 85.7% HIV+ve pregnant women 14 Passive latex agglutination (CMV-scan card) [24]

Benin (Cotonou) 97.2% Pregnant women 211 ETI-CYTOK-G PLUS ELISA (DiaSorin) [31]

Nigeria (Ibadan) 100% Pregnant (some not pregnant) women 80 peroxidase enzyme-labelled antigen (ELA) [5]

South Africa (Johannesburg) 86.4% Pregnant Women 2160 ELISA (M A Bioproducts, Virginia) [32]

Cameroon (Kumba City) 88.5% Healthy Children 4-6 years ~100 ELISA (unspecified) [33]

Cameroon (Kumba City) 98.0% Healthy Children 11-14 years ~100 ELISA (unspecified) [33]

Gambia (Banjul) 86.4% Healthy Children 12 months 178 Immunofluoruescence? [4]

Mozambique (SE Transvaal) 88.0% Refugee Children under 5yrs ~100 ELISA (unspecified) [34]

Mozambique (SE Transvaal) 96.4% Refugee Children under 11 years ~100 ELISA (unspecified) [34]

Human Cytomegalovirus (HCMV) Infection in Sub-Saharan Africa

http://dx.doi.org/10.5772/54907

Nigeria (Ibadan) 100% Newborn Infants 21 peroxidase enzyme-labelled antigen (ELA) [5]

Zambia (Lusaka) 83% Healthy 18-month old infants 460 ETI-CYTOK-G PLUS ELISA (DiaSorin) [3]

Kenya (Nairobi) 100% HIV-1 infected street children 71 ELISA kit (Murex) [35]

Nigeria (Ibadan) 50.6% Non-TB 89 Compliment fixation [22]

Nigeria (Ibadan) 87.6% Tuberculosis Patients 161 Compliment fixation [22]

Burkina Faso (Bobo Dioulasso) 95.0% TB+ HIV+ve 40 ELISA (Platelia® Sanofi Pasteur) [26]

Burkina Faso (Bobo Dioulasso) 96.5% Tuberculosis Patients 80 ELISA (Platelia® Sanofi Pasteur) [26]

Burkina Faso (Bobo Dioulasso) 97.5% TB+ HIV-ve 40 ELISA (Platelia® Sanofi Pasteur) [26]

Eritrea (various locations) 94.8% Various 439 ELISA (unspecified) [36]

Burundi (Bujumbura) 99.0% Ophthalmic patients 154 ELISA Enzygnost CMV (Abbott Laboratories, Chicago, IL, USA [37]

**Other 95.9%** 

**Tuberculosis studies 83.0%** 

**Children 88.4%** 

**Pregnant Women 86.3%** 

**Table 1.** Comparison of HCMV seroprevalence in different countries \* Percentages in bold are the averages within

**HIV+ Adults 80.0%** 

**AIDS Patients**

**81.9%** 

**HIV- Adults 79.3%**

each group, weighted by study size.

**Figure 1.** Model for the cumulative prevalence of primary HCMV seroconversion by age with respect to socioeconom‐ ic status (SES) groups.


with increased HCMV seroprevalence. This supports the notion that seronegative adult women contract primary HCMV infection from children who are shedding virus [8]. Figure 1 presents a model for cumulative HCMV seroprevalence by age with respect to SES, showing more rapid uptake in low SES communities, and delayed uptake in high SES communities. Conversely an Israeli study found the effect of ethnicity persisted even when corrected for gender, education and SES [9], and high HCMV seroprevalence has been described in

Whilst lower SES may be the main driver for endemic infant HCMV primary infection in sub-Saharan Africa, this is not the whole story. What factors, attributable to low SES, facilitate earlier HCMV transmission? HCMV is primarily transmitted through body fluids, being shed in urine, saliva [12, 13] and breast milk [14, 15]. In Nigeria, over-crowding was significantly associated with being HCMV seropositive, but source of drinking water, place of abode and type of toilet facility were not [16]. Some individuals remain seronegative into old age - even in sub-Saharan Africa where most people are infected in infancy. Human genetic variations may block or impair HCMV primary infection, as is seen with the CCR5 ∆32 mutation and HIV [17]. HCMV seronegative individuals have increased longevity, possibly linked with reduced clonal expansion of CD8 T cells and a larger reservoir of circulating naive T cells [18, 19] so early childhood primary infection with HCMV in sub-Saharan Africa may have profound effects. There is evidence linking early HCMV infections in sub-Saharan Africa with impaired physical and mental development [3], analogous to the known developmental CNS defects (hearing loss, mental retardation, cerebral palsy, seizures, chorioretinitis) caused by

**Figure 1.** Model for the cumulative prevalence of primary HCMV seroconversion by age with respect to socioeconom‐

populations with high SES groups [10, 11].

18 Manifestations of Cytomegalovirus Infection

congenital HCMV infection [20, 21].

ic status (SES) groups.

**Table 1.** Comparison of HCMV seroprevalence in different countries \* Percentages in bold are the averages within each group, weighted by study size.

1

#### *1.1.2. Molecular epidemiology*

HCMV has a large genome, predicted to encode at least 165 proteins. This includes hyper‐ variable segments [38-41] containing genes which encode membrane-bound glycoproteins. These are embedded in the virion envelope or presented on the surface of infected cells, making them candidate targets for the host immune response. Most published studies of polymor‐ phisms in these glycoproteins have concentrated on possible associations with and clinical disease or cellular tropism. No compelling connections have been reported in the literature to date, but much of the sequence data is from isolates from Europe, North America and Japan.

**2.2. Disease presentations and co-morbidity**

**2.3. HCMV as a cause of death**

0-8.5% of adult AIDS patients with ophthalmic conditions [77-83].

thological evidence of active HCMV infection post-mortem [92].

**3. HCMV pneumonia in HIV infected children**

infections and remain undiagnosed and untreated.

The most common presentation of HCMV infection in HIV-infected patients is HCMV pneumonia, where co-infection with other respiratory pathogens such a tuberculosis and *Pneumocystis jirovecci,* is almost ubiquitous [50, 60]. HCMV is an important HIV co-infection, also linked with a range diseases including meningitis [62], encephalitis [63], psychological disorders [64], malaria [65], various dermatological conditions [66, 67] and those affecting mucosal epithelia [68, 69], hypoadrenalism [70], adrenalitis [71], gastritis [72, 73] and other herpesvirus infections [74]. There has been a huge (possibly disproportionate) focus on HCMV as a cause of HIV-associated retinitis. Globally it has been estimated that 5-25% of AIDS patients will suffer from HCMV retinitis in their lifetime [75] leading to an 'epidemic of blindness' [76]. Whilst the cohorts and diagnostic methods vary in different studies, HIVassociated HCMV retinitis is less common in sub-Saharan Africa than elsewhere, seen in just

Human Cytomegalovirus (HCMV) Infection in Sub-Saharan Africa

http://dx.doi.org/10.5772/54907

21

It is unclear how much active HCMV infection is contributing to mortality in HIV infected people. One way to address this question is to measure mortality as a primary outcome. For example: a large longitudinal study of HIV infected miners in South Africa associated HCMV viraemia with a three-fold increase in mortality after just 11 months. The affect was weakened when controlling for CD4 T-cell count, WHO stage and HIV viral load– all conditions predic‐ tive of mortality [84]. A study of HIV-infected and -exposed Kenyan children found a strong correlation between HIV-1 and HCMV viral loads. Adjusting for maternal immunosuppres‐ sion and HIV-1 viral load, HCMV viraemia during pregnancy was linked with high risk of death for mothers and infants in the 2 years following delivery [85]. It is difficult to prove that HCMV viraemia is not simply a bystander and is actually involved in pathology. This requires post mortem studies, which are difficult due to cultural factors [86]. Paediatric post mortem studies from sub-Saharan Africa identify HCMV as a common cause of death [87, 88], espe‐ cially in HIV infected patients [89-91]. There is a need for new post-mortem data, from both prospective studies and routine cases, to better inform on the prevalence of active HCMV as a cause of death, and in particular, to calibrate HCMV viral loads pre-mortem with histopa‐

Pneumonia is the most common cause of death in children <5 yrs of age globally, accounting for 18% of all deaths [93]. In sub-Saharan Africa, pneumonia is the leading cause of death in HIV-infected and -exposed children [94-97]. Across the region antibiotics are cheap and widely available, yet pneumonia is still a major cause of paediatric mortality. This is likely in part due to antibiotic resistance [98], but also several viral pathogens cause lower respiratory tract

There is little information regarding HCMV genotypes in Africa. In an early study investigat‐ ing geographic differences in the frequency of certain HCMV genotypes from immunocom‐ promised patients, they found that the distribution differed between Zimbabwe, Italy and California [42]. This study was limited to UL55 (virion surface glycoprotein gB: involved in cell entry and signaling)[43] which is relatively conserved between strains [40] and not linked with more variable glycoproteins [44]. A study of HCMV strains from 19 Malawian Kaposi's sarcoma (KS) patients and 58 of their first-degree relatives detected HCMV readily in mouth rinse and urine specimens [45]. Two hypervariable glycoprotein genes were sequenced: gO (UL74) and gN (UL73) involved in promoting focal spread [46, 47] and virion morphogenesis and possible latency associated functions respectively [48, 49]. Studies from Zambia segregate variants of these two glycoproteins into eight linked groups [50, 51]. These studies and others from Africa have found evidence of co-infections with multiple HCMV strains [50, 52] and no evidence for geographic separation. This data contrasts with other herpesviruses such as HHV-6 [53] and KSHV [54]. The high prevalence of co-infections with multiple strains, in a broad range of patients, complicates genotyping studies and attempts to identify disease links with specific glycoprotein genotypes. New techniques combining PCR amplification with RFLP digestion could improve analysis of multiple strains and recombinants in pathological samples [55].

#### **2. HCMV infections and HIV in Sub-Saharan Africa**

#### **2.1. General considerations**

sub-Saharan Africa is at the epicentre of the HIV pandemic, with 1,900,000 new infections (18.9% children ≤ 14yrs of age) in 2010, and a total of 23.2 million people (13.4% children ≤ 14yrs of age) living with HIV. Progress is slow but new infections are down 16% on 2001, and HIV prevalence has declined in some sub-Saharan African countries. With the roll out of antiretroviral therapy (ART), the numbers of people dying from HIV is also down (30% decrease between 2004 and 2010) [56]. HCMV is an apex opportunistic pathogen, linked with HIV disease progression [57-59], so the HIV pandemic combined with over 80% of primary HCMV infections occurring during infancy, creates a unique environment. Active HCMV infections are common and present as complex co-infections with other viral, bacterial and fungal infections [60, 61]. A broader awareness of the frequency of co-infections and the complex interplay between different pathogens is needed.

#### **2.2. Disease presentations and co-morbidity**

*1.1.2. Molecular epidemiology*

20 Manifestations of Cytomegalovirus Infection

samples [55].

**2.1. General considerations**

**2. HCMV infections and HIV in Sub-Saharan Africa**

complex interplay between different pathogens is needed.

sub-Saharan Africa is at the epicentre of the HIV pandemic, with 1,900,000 new infections (18.9% children ≤ 14yrs of age) in 2010, and a total of 23.2 million people (13.4% children ≤ 14yrs of age) living with HIV. Progress is slow but new infections are down 16% on 2001, and HIV prevalence has declined in some sub-Saharan African countries. With the roll out of antiretroviral therapy (ART), the numbers of people dying from HIV is also down (30% decrease between 2004 and 2010) [56]. HCMV is an apex opportunistic pathogen, linked with HIV disease progression [57-59], so the HIV pandemic combined with over 80% of primary HCMV infections occurring during infancy, creates a unique environment. Active HCMV infections are common and present as complex co-infections with other viral, bacterial and fungal infections [60, 61]. A broader awareness of the frequency of co-infections and the

HCMV has a large genome, predicted to encode at least 165 proteins. This includes hyper‐ variable segments [38-41] containing genes which encode membrane-bound glycoproteins. These are embedded in the virion envelope or presented on the surface of infected cells, making them candidate targets for the host immune response. Most published studies of polymor‐ phisms in these glycoproteins have concentrated on possible associations with and clinical disease or cellular tropism. No compelling connections have been reported in the literature to date, but much of the sequence data is from isolates from Europe, North America and Japan. There is little information regarding HCMV genotypes in Africa. In an early study investigat‐ ing geographic differences in the frequency of certain HCMV genotypes from immunocom‐ promised patients, they found that the distribution differed between Zimbabwe, Italy and California [42]. This study was limited to UL55 (virion surface glycoprotein gB: involved in cell entry and signaling)[43] which is relatively conserved between strains [40] and not linked with more variable glycoproteins [44]. A study of HCMV strains from 19 Malawian Kaposi's sarcoma (KS) patients and 58 of their first-degree relatives detected HCMV readily in mouth rinse and urine specimens [45]. Two hypervariable glycoprotein genes were sequenced: gO (UL74) and gN (UL73) involved in promoting focal spread [46, 47] and virion morphogenesis and possible latency associated functions respectively [48, 49]. Studies from Zambia segregate variants of these two glycoproteins into eight linked groups [50, 51]. These studies and others from Africa have found evidence of co-infections with multiple HCMV strains [50, 52] and no evidence for geographic separation. This data contrasts with other herpesviruses such as HHV-6 [53] and KSHV [54]. The high prevalence of co-infections with multiple strains, in a broad range of patients, complicates genotyping studies and attempts to identify disease links with specific glycoprotein genotypes. New techniques combining PCR amplification with RFLP digestion could improve analysis of multiple strains and recombinants in pathological

The most common presentation of HCMV infection in HIV-infected patients is HCMV pneumonia, where co-infection with other respiratory pathogens such a tuberculosis and *Pneumocystis jirovecci,* is almost ubiquitous [50, 60]. HCMV is an important HIV co-infection, also linked with a range diseases including meningitis [62], encephalitis [63], psychological disorders [64], malaria [65], various dermatological conditions [66, 67] and those affecting mucosal epithelia [68, 69], hypoadrenalism [70], adrenalitis [71], gastritis [72, 73] and other herpesvirus infections [74]. There has been a huge (possibly disproportionate) focus on HCMV as a cause of HIV-associated retinitis. Globally it has been estimated that 5-25% of AIDS patients will suffer from HCMV retinitis in their lifetime [75] leading to an 'epidemic of blindness' [76]. Whilst the cohorts and diagnostic methods vary in different studies, HIVassociated HCMV retinitis is less common in sub-Saharan Africa than elsewhere, seen in just 0-8.5% of adult AIDS patients with ophthalmic conditions [77-83].

#### **2.3. HCMV as a cause of death**

It is unclear how much active HCMV infection is contributing to mortality in HIV infected people. One way to address this question is to measure mortality as a primary outcome. For example: a large longitudinal study of HIV infected miners in South Africa associated HCMV viraemia with a three-fold increase in mortality after just 11 months. The affect was weakened when controlling for CD4 T-cell count, WHO stage and HIV viral load– all conditions predic‐ tive of mortality [84]. A study of HIV-infected and -exposed Kenyan children found a strong correlation between HIV-1 and HCMV viral loads. Adjusting for maternal immunosuppres‐ sion and HIV-1 viral load, HCMV viraemia during pregnancy was linked with high risk of death for mothers and infants in the 2 years following delivery [85]. It is difficult to prove that HCMV viraemia is not simply a bystander and is actually involved in pathology. This requires post mortem studies, which are difficult due to cultural factors [86]. Paediatric post mortem studies from sub-Saharan Africa identify HCMV as a common cause of death [87, 88], espe‐ cially in HIV infected patients [89-91]. There is a need for new post-mortem data, from both prospective studies and routine cases, to better inform on the prevalence of active HCMV as a cause of death, and in particular, to calibrate HCMV viral loads pre-mortem with histopa‐ thological evidence of active HCMV infection post-mortem [92].

#### **3. HCMV pneumonia in HIV infected children**

Pneumonia is the most common cause of death in children <5 yrs of age globally, accounting for 18% of all deaths [93]. In sub-Saharan Africa, pneumonia is the leading cause of death in HIV-infected and -exposed children [94-97]. Across the region antibiotics are cheap and widely available, yet pneumonia is still a major cause of paediatric mortality. This is likely in part due to antibiotic resistance [98], but also several viral pathogens cause lower respiratory tract infections and remain undiagnosed and untreated.

HCMV pneumonia is very common in HIV-infected and –exposed in sub-Saharan Africa [99, 100] and is associated with rapid progression of HIV disease [101] and death [102-104]. A seminal post mortem study in 264 Zambian children who died of respiratory disease identified classical HCMV inclusions in the lung tissue of up to 22% of HIV-infected cases [60], and then follow-up molecular work found high loads of HCMV were virtually ubiquitous in the lung tissue of HIV-infected paediatric respiratory deaths [50]. HCMV pneumonia is virtually impossible to distinguish clinically from *Pneumocystis jirovecci* pneumonia and co-infections with both *Pneumocystis jirovecci* and tuberculosis are common in HIV-infected and -exposed infants [60, 61, 105]. In South Africa, HCMV pneumonia was more common than *Pneumocystis jirovecci* pneumonia and other viral pneumonias in HIV-infected children [106], and was histologically confirmed in 72% of HIV-infected and ventilated infant mortalities with severe pneumonia. The authors recommend empiric use of ganciclovir or other anti-HCMV drugs in HIV-infected children with severe pneumonia who are not responding to co-trimoxazole [107].

a study from Zambia has shown that HCMV seroprevalence in 18 month old infants is linked with impaired growth and mental development [3]. There is a need for more prospective studies to investigate the clinical significance of congenital HCMV infections in sub-Saharan

One of the greatest challenges for HCMV diagnosis in this region is to differentiate clinically active from sub-clinical infection. Serological tests for HCMV IgM are useful for diagnosing primary infections in infants, particularly congenital infections in neonates, but the majority of the disease burden is caused by re-activation or re-infections in immunocompromised patients. Detection of the virus itself was traditionally achieved using culture-based methods. These are time-consuming and require well-trained staff and a well-serviced diagnostic laboratory. Moreover, HCMV culture is not very sensitive. For these reasons, quantitative DNA-based molecular diagnostics are now commonly used to detect active HCMV infections. The required infrastructure is becoming commonly available at tertiary and secondary referral centres across sub-Saharan Africa, often donated by international research projects. However low level HCMV reactivations are common in a wide range of patients, linked with reduced

Most studies of HCMV viral loads with respect to disease outcomes are in the transplant field,

be indicative of active disease, depending on the specific patient group [125]. An autopsy study

value of 100% for HCMV disease, making the commercial assay used (COBAS AMPLICOR CMV Monitor test - Roche) better for 'ruling in', than 'ruling out' [126]. There is a need for prospective studies in sub-Saharan Africa to monitor HCMV viral loads in patients with HIVassociated pneumonia, and infants with congenital HCMV infection, the two major HCMV disease groups in the region – although there are also transplant recipients in sub-Saharan Africa [127]. HCMV is shed in high loads in both urine and saliva (non-invasive specimens ideal for low income settings) and detection of virus DNA in these specimens should be

Several drugs are licensed for the treatment of HCMV infections, although they are expensive and broadly unavailable in sub-Saharan Africa. At some tertiary referral centres in South Africa, intravenous ganciclovir is used to treat HCMV pneumonia in HIV-infected and exposed children failing antibiotic or anti-mycobacterial therapy. Decisions are largely consultant led but two descriptive studies have reported dramatic reductions in mortality due to ganciclovir [106, 107]. Readers are advised to look up the latest guidelines on treatment of HCMV and to check the correct doses, side effects and dosing schedules. In South African centres, PCR or culture-proven HCMV disease is typically treated with 5mg/kg intravenously every 12hrs for 14-21 days, and then daily maintenance therapy at 5mg/kg [94]. But there is an

to 106 copies/ml whole blood have been suggested to

Human Cytomegalovirus (HCMV) Infection in Sub-Saharan Africa

http://dx.doi.org/10.5772/54907

23

copies/ml whole blood, gave a specificity and positive predictive

immune surveillance due to other infections, illness or malnutrition.

evaluated versus viraemia, as potentially useful markers of active disease.

Africa.

**5. HCMV diagnosis and treatment**

where viral loads within the range of 104

found that a cut off of 104

**in Sub-Saharan Africa**

#### **4. HCMV Congenital Infection in sub-Saharan Africa**

Congenital HCMV is generally defined by the detection of viral DNA and/or IgM antibody in infant sera within the first 3 weeks post-partum [108]. It is a damaging infection initiated by either primary or reactivated infection in the mother during pregnancy, although congenital HCMV infections transmitted from mothers with pre-existing immunity can be less severe [109]. Congenital HCMV is the major viral cause of mental and physical disability in children, infecting 0.2-2.2% of newborns [110, 111]. Around 7-11% of infected foetuses are then born with symptoms [112, 113], with a neonatal mortality rate of 20-30% [114, 115]. Of those congenitally infected (both symptomatic and asymptomatic), up to 28% will develop late sequelae [116]. Symptoms include growth retardation, hepatosplenomegaly, jaundice, pneumonia, gastrointestinal, and neurological disease such as sensorineural hearing loss, mental retardation, chorioretinitis, seizures [117] and cerebral palsy [118].

Congenital HCMV infection was considered rare in populations with high adult seropreva‐ lence [33]. A study of 2032 newborn infants in the Ivory Coast cultured HCMV from urine and showed congenital HCMV infection in 1.4% of all births [119]. In sub-Saharan Africa, congen‐ ital HCMV largely reflects maternal reactivations or re-infections, which may not result in severe disease in the child [109]. However, a few studies from the region suggest congenital HCMV maybe a significant cause of morbidity and mortality. A study from Zambia associated HCMV antibody titres above 1:1024 with still births [120]. HCMV IgM antibodies were detected in 24% of 99 newborn babies who were jaundiced, died within a few days of birth or showed gross congenital abnormalities [121]. Cervical shedding of HCMV is very common in HIV-infected women, and is readily detected in amniotic fluid collected at C-section [122, 123]. A Gambian study found the prevalence of congenital CMV among healthy neonates was 5.4%, at least 2-fold higher than reported in industrialized countries. Congenitally infected children were more often first born babies, more frequently born in crowded compounds and active placental malaria was more prevalent. During the first year of follow up, mothers of congenitally infected children reported more health complaints for their child [124]. Recently a study from Zambia has shown that HCMV seroprevalence in 18 month old infants is linked with impaired growth and mental development [3]. There is a need for more prospective studies to investigate the clinical significance of congenital HCMV infections in sub-Saharan Africa.

### **5. HCMV diagnosis and treatment in Sub-Saharan Africa**

HCMV pneumonia is very common in HIV-infected and –exposed in sub-Saharan Africa [99, 100] and is associated with rapid progression of HIV disease [101] and death [102-104]. A seminal post mortem study in 264 Zambian children who died of respiratory disease identified classical HCMV inclusions in the lung tissue of up to 22% of HIV-infected cases [60], and then follow-up molecular work found high loads of HCMV were virtually ubiquitous in the lung tissue of HIV-infected paediatric respiratory deaths [50]. HCMV pneumonia is virtually impossible to distinguish clinically from *Pneumocystis jirovecci* pneumonia and co-infections with both *Pneumocystis jirovecci* and tuberculosis are common in HIV-infected and -exposed infants [60, 61, 105]. In South Africa, HCMV pneumonia was more common than *Pneumocystis jirovecci* pneumonia and other viral pneumonias in HIV-infected children [106], and was histologically confirmed in 72% of HIV-infected and ventilated infant mortalities with severe pneumonia. The authors recommend empiric use of ganciclovir or other anti-HCMV drugs in HIV-infected children with severe pneumonia who are not responding to co-trimoxazole [107].

Congenital HCMV is generally defined by the detection of viral DNA and/or IgM antibody in infant sera within the first 3 weeks post-partum [108]. It is a damaging infection initiated by either primary or reactivated infection in the mother during pregnancy, although congenital HCMV infections transmitted from mothers with pre-existing immunity can be less severe [109]. Congenital HCMV is the major viral cause of mental and physical disability in children, infecting 0.2-2.2% of newborns [110, 111]. Around 7-11% of infected foetuses are then born with symptoms [112, 113], with a neonatal mortality rate of 20-30% [114, 115]. Of those congenitally infected (both symptomatic and asymptomatic), up to 28% will develop late sequelae [116]. Symptoms include growth retardation, hepatosplenomegaly, jaundice, pneumonia, gastrointestinal, and neurological disease such as sensorineural hearing loss,

Congenital HCMV infection was considered rare in populations with high adult seropreva‐ lence [33]. A study of 2032 newborn infants in the Ivory Coast cultured HCMV from urine and showed congenital HCMV infection in 1.4% of all births [119]. In sub-Saharan Africa, congen‐ ital HCMV largely reflects maternal reactivations or re-infections, which may not result in severe disease in the child [109]. However, a few studies from the region suggest congenital HCMV maybe a significant cause of morbidity and mortality. A study from Zambia associated HCMV antibody titres above 1:1024 with still births [120]. HCMV IgM antibodies were detected in 24% of 99 newborn babies who were jaundiced, died within a few days of birth or showed gross congenital abnormalities [121]. Cervical shedding of HCMV is very common in HIV-infected women, and is readily detected in amniotic fluid collected at C-section [122, 123]. A Gambian study found the prevalence of congenital CMV among healthy neonates was 5.4%, at least 2-fold higher than reported in industrialized countries. Congenitally infected children were more often first born babies, more frequently born in crowded compounds and active placental malaria was more prevalent. During the first year of follow up, mothers of congenitally infected children reported more health complaints for their child [124]. Recently

**4. HCMV Congenital Infection in sub-Saharan Africa**

22 Manifestations of Cytomegalovirus Infection

mental retardation, chorioretinitis, seizures [117] and cerebral palsy [118].

One of the greatest challenges for HCMV diagnosis in this region is to differentiate clinically active from sub-clinical infection. Serological tests for HCMV IgM are useful for diagnosing primary infections in infants, particularly congenital infections in neonates, but the majority of the disease burden is caused by re-activation or re-infections in immunocompromised patients. Detection of the virus itself was traditionally achieved using culture-based methods. These are time-consuming and require well-trained staff and a well-serviced diagnostic laboratory. Moreover, HCMV culture is not very sensitive. For these reasons, quantitative DNA-based molecular diagnostics are now commonly used to detect active HCMV infections. The required infrastructure is becoming commonly available at tertiary and secondary referral centres across sub-Saharan Africa, often donated by international research projects. However low level HCMV reactivations are common in a wide range of patients, linked with reduced immune surveillance due to other infections, illness or malnutrition.

Most studies of HCMV viral loads with respect to disease outcomes are in the transplant field, where viral loads within the range of 104 to 106 copies/ml whole blood have been suggested to be indicative of active disease, depending on the specific patient group [125]. An autopsy study found that a cut off of 104 copies/ml whole blood, gave a specificity and positive predictive value of 100% for HCMV disease, making the commercial assay used (COBAS AMPLICOR CMV Monitor test - Roche) better for 'ruling in', than 'ruling out' [126]. There is a need for prospective studies in sub-Saharan Africa to monitor HCMV viral loads in patients with HIVassociated pneumonia, and infants with congenital HCMV infection, the two major HCMV disease groups in the region – although there are also transplant recipients in sub-Saharan Africa [127]. HCMV is shed in high loads in both urine and saliva (non-invasive specimens ideal for low income settings) and detection of virus DNA in these specimens should be evaluated versus viraemia, as potentially useful markers of active disease.

Several drugs are licensed for the treatment of HCMV infections, although they are expensive and broadly unavailable in sub-Saharan Africa. At some tertiary referral centres in South Africa, intravenous ganciclovir is used to treat HCMV pneumonia in HIV-infected and exposed children failing antibiotic or anti-mycobacterial therapy. Decisions are largely consultant led but two descriptive studies have reported dramatic reductions in mortality due to ganciclovir [106, 107]. Readers are advised to look up the latest guidelines on treatment of HCMV and to check the correct doses, side effects and dosing schedules. In South African centres, PCR or culture-proven HCMV disease is typically treated with 5mg/kg intravenously every 12hrs for 14-21 days, and then daily maintenance therapy at 5mg/kg [94]. But there is an urgent need for further descriptive studies to identify patients for treatment. Randomized controlled clinical trials are needed to evaluate safety and efficacy.

types, although IE gene transcripts have not been detected in T- or B-lymphocytes [145, 146]. Despite this, HCMV influences cell-mediated immunity. T-cell populations in HCMV-infected infants in the Gambia showed higher levels of differentiation [147, 148] and similar HCMVinduced differentiation in elderly non-African populations is associated with depleted naive T-cell populations and impaired vaccine responses [149]. HCMV infection is also associated with a decline in naive T cells and impaired T-cell reconstitution in HIV infected adults initiating HAART [150]. But naive T-cell populations appear unaffected by HCMV infection in African children, and infection was not linked with impaired T-cell responses to measles virus vaccination [151], with HCMV activated T-helpers possibly improving measles antibody response [152]. A study in older African children, found that HIV-negative Malawian teen‐ agers had a lower percentage of naïve T cells, higher memory T and higher CD28- memory Tcells, compared to age-matched UK teenagers. Whilst all of the adolescents tested in Malawi were seropositive for HCMV, seroprevalence was just 36% in the UK group, and was associated with a reduced percentage of naïve T cells and an increased percentage of CD28- memory T

Human Cytomegalovirus (HCMV) Infection in Sub-Saharan Africa

http://dx.doi.org/10.5772/54907

25

Whilst more evidence is required, these studies suggest early infant infection with HCMV, and maybe a general higher burden of infectious disease, contribute to a more rapid ageing of the immune system in sub-Saharan Africa. Whilst access to anti-HCMV drugs would likely significantly reduce morbidity and mortality in acute HCMV infections, such as congenitally infected infants or HIV/AIDS patients with pneumonia or disseminated HCMV, the implica‐ tions of a successful HCMV vaccine have potentially far-reaching benefits across the region. Future studies evaluating vaccine efficacy in sub-Saharan Africa should stratify by HCMV serostatus, and where facilities permit, include work on HCMV genotypes and flow cytometric

In sub-Saharan Africa, HCMV infection is endemic in young infants where it is linked with impaired physical and mental development [3], giving the infection a unique epidemiology across the region, with a potentially broad-reaching impact on the health of southern African populations. Studies conducted in sub-Saharan Africa and elsewhere, have shown that HCMV is a serious cause or morbidity and mortality, in both immunocompromised groups and congenitally infected children. In a region where 23.2 million people are living with HIV and most of the population are infected with HCMV in infancy [124], more prospective studies are required to better characterise the impact of HCMV in sub-Saharan Africa. This will lay the foundations for future clinical trials of anti-HCMV drugs in patient sub-sets in whom there is strong evidence that they might be effective. Drugs such as ganciclovir are already used in South Africa as life-saving treatment for HIV-infected children with severe pneumonia that is not responsive to antibiotic or anti-mycobacterial therapy. Furthermore, the clinical impact and importance of HCMV infections in sub-Saharan Africa may increase over the next decade for several reasons: Wider access to ART is resulting in increasing numbers of older HIV infected patients; Cancer incidence is forecast to increase by 32% across sub-Saharan Africa

analysis to further characterise the effect of infant HCMV infection on immunity.

cells in the periphery [153].

**7. Summary**

The introduction of expensive antiviral treatments in low income settings is always problem‐ atic; Ethics review boards may state that it is unethical to trial antiviral drugs which are unaffordable and inaccessible to the majority of the affected patients. The path to new treatments has to start somewhere, and as scientists we favour evidence as the basis for action. The case of CD4 testing and antiretroviral therapy has proven that resources can be mobilized from a range of stake holders, including governments, NGOs and private enterprise [128-130]. A second ethical dilemma is that if the drug is being used successfully in South Africa to treat HIV-associated HCMV pneumonia, is it ethical for Ganciclovir trials to administer placebos? When answering such ethical questions we should note that HCMV affects a broad range of patient groups across sub-Saharan Africa, including congenitally infected neonates, HIV infected infants, children and adults causing pneumonia, specific organ disease (eg. retinitis, encephalitis, gastritis) and disseminated infection. Furthermore, malnutrition and co-infection with other common pathogens (Malaria, Tuberculosis, *Pneumocystis Jirovecci* etc..) are preva‐ lent. For this diverse patient group, the evidence base for the optimal dose, duration and route of administration is poor [131].

#### **6. Effect of HCMV on vaccine efficacy and immune senescence in Sub-Saharan Africa**

Infant vaccination programmes are a central component of national paediatric disease prevention strategies in sub-Saharan Africa [132], but they are less effective than equivalent programmes in high income populations. For example: The efficacy of live attenuated measles virus vaccine in Europe and North America is over 90% [133-135] whereas in West Africa it is below 70% [136-138]. This could be partly due to the higher infectious disease burden in sub-Saharan Africa, which may affect antibody [139, 140] and cytokine [141] responses to vacci‐ nation, and also reduced vaccine performance in HIV-infected children [132]. With 3.1 million children living with HIV/AIDS across the region [56], vaccine safety and efficacy must be independently assessed in this significant and vulnerable patient group. HIV-infected children can generally seroconvert in response to both live-attenuated and inactivated/subunit vac‐ cines, but the immune response is generally weaker with lower antibody levels and seropro‐ tection rates in HIV-infected children [142-144]. The weaker immune response in HIV-infected children could be due to defective antigen presentation, defective B-cell priming or impaired differentiation into memory cells, impaired primary response due to low CD4, loss of protec‐ tive antibodies or loss of immunological memory of T and B cells after priming [143].

Most HIV-infected children in sub-Saharan Africa will also be infected with HCMV, which encodes over thirty genes with potential immunomodulatory functions. These genes may affect classical and non-classical major histocompatibility complex (MHC) protein function, leukocyte migration and activation, cytokine responses and host cell susceptibility to apoptosis [43]. HCMV can infect and initiate gene expression in an extraordinarily broad range of cell types, although IE gene transcripts have not been detected in T- or B-lymphocytes [145, 146]. Despite this, HCMV influences cell-mediated immunity. T-cell populations in HCMV-infected infants in the Gambia showed higher levels of differentiation [147, 148] and similar HCMVinduced differentiation in elderly non-African populations is associated with depleted naive T-cell populations and impaired vaccine responses [149]. HCMV infection is also associated with a decline in naive T cells and impaired T-cell reconstitution in HIV infected adults initiating HAART [150]. But naive T-cell populations appear unaffected by HCMV infection in African children, and infection was not linked with impaired T-cell responses to measles virus vaccination [151], with HCMV activated T-helpers possibly improving measles antibody response [152]. A study in older African children, found that HIV-negative Malawian teen‐ agers had a lower percentage of naïve T cells, higher memory T and higher CD28- memory Tcells, compared to age-matched UK teenagers. Whilst all of the adolescents tested in Malawi were seropositive for HCMV, seroprevalence was just 36% in the UK group, and was associated with a reduced percentage of naïve T cells and an increased percentage of CD28- memory T cells in the periphery [153].

Whilst more evidence is required, these studies suggest early infant infection with HCMV, and maybe a general higher burden of infectious disease, contribute to a more rapid ageing of the immune system in sub-Saharan Africa. Whilst access to anti-HCMV drugs would likely significantly reduce morbidity and mortality in acute HCMV infections, such as congenitally infected infants or HIV/AIDS patients with pneumonia or disseminated HCMV, the implica‐ tions of a successful HCMV vaccine have potentially far-reaching benefits across the region. Future studies evaluating vaccine efficacy in sub-Saharan Africa should stratify by HCMV serostatus, and where facilities permit, include work on HCMV genotypes and flow cytometric analysis to further characterise the effect of infant HCMV infection on immunity.

#### **7. Summary**

urgent need for further descriptive studies to identify patients for treatment. Randomized

The introduction of expensive antiviral treatments in low income settings is always problem‐ atic; Ethics review boards may state that it is unethical to trial antiviral drugs which are unaffordable and inaccessible to the majority of the affected patients. The path to new treatments has to start somewhere, and as scientists we favour evidence as the basis for action. The case of CD4 testing and antiretroviral therapy has proven that resources can be mobilized from a range of stake holders, including governments, NGOs and private enterprise [128-130]. A second ethical dilemma is that if the drug is being used successfully in South Africa to treat HIV-associated HCMV pneumonia, is it ethical for Ganciclovir trials to administer placebos? When answering such ethical questions we should note that HCMV affects a broad range of patient groups across sub-Saharan Africa, including congenitally infected neonates, HIV infected infants, children and adults causing pneumonia, specific organ disease (eg. retinitis, encephalitis, gastritis) and disseminated infection. Furthermore, malnutrition and co-infection with other common pathogens (Malaria, Tuberculosis, *Pneumocystis Jirovecci* etc..) are preva‐ lent. For this diverse patient group, the evidence base for the optimal dose, duration and route

**6. Effect of HCMV on vaccine efficacy and immune senescence in Sub-**

Infant vaccination programmes are a central component of national paediatric disease prevention strategies in sub-Saharan Africa [132], but they are less effective than equivalent programmes in high income populations. For example: The efficacy of live attenuated measles virus vaccine in Europe and North America is over 90% [133-135] whereas in West Africa it is below 70% [136-138]. This could be partly due to the higher infectious disease burden in sub-Saharan Africa, which may affect antibody [139, 140] and cytokine [141] responses to vacci‐ nation, and also reduced vaccine performance in HIV-infected children [132]. With 3.1 million children living with HIV/AIDS across the region [56], vaccine safety and efficacy must be independently assessed in this significant and vulnerable patient group. HIV-infected children can generally seroconvert in response to both live-attenuated and inactivated/subunit vac‐ cines, but the immune response is generally weaker with lower antibody levels and seropro‐ tection rates in HIV-infected children [142-144]. The weaker immune response in HIV-infected children could be due to defective antigen presentation, defective B-cell priming or impaired differentiation into memory cells, impaired primary response due to low CD4, loss of protec‐

tive antibodies or loss of immunological memory of T and B cells after priming [143].

Most HIV-infected children in sub-Saharan Africa will also be infected with HCMV, which encodes over thirty genes with potential immunomodulatory functions. These genes may affect classical and non-classical major histocompatibility complex (MHC) protein function, leukocyte migration and activation, cytokine responses and host cell susceptibility to apoptosis [43]. HCMV can infect and initiate gene expression in an extraordinarily broad range of cell

controlled clinical trials are needed to evaluate safety and efficacy.

of administration is poor [131].

24 Manifestations of Cytomegalovirus Infection

**Saharan Africa**

In sub-Saharan Africa, HCMV infection is endemic in young infants where it is linked with impaired physical and mental development [3], giving the infection a unique epidemiology across the region, with a potentially broad-reaching impact on the health of southern African populations. Studies conducted in sub-Saharan Africa and elsewhere, have shown that HCMV is a serious cause or morbidity and mortality, in both immunocompromised groups and congenitally infected children. In a region where 23.2 million people are living with HIV and most of the population are infected with HCMV in infancy [124], more prospective studies are required to better characterise the impact of HCMV in sub-Saharan Africa. This will lay the foundations for future clinical trials of anti-HCMV drugs in patient sub-sets in whom there is strong evidence that they might be effective. Drugs such as ganciclovir are already used in South Africa as life-saving treatment for HIV-infected children with severe pneumonia that is not responsive to antibiotic or anti-mycobacterial therapy. Furthermore, the clinical impact and importance of HCMV infections in sub-Saharan Africa may increase over the next decade for several reasons: Wider access to ART is resulting in increasing numbers of older HIV infected patients; Cancer incidence is forecast to increase by 32% across sub-Saharan Africa between 2010 and 2020 [154]; The number of transplant recipients is also set to increase, as the capacity of tertiary care centres develops and improves.

[3] Gompels UA, Larke N, Sanz-Ramos M, Bates M, Musonda K, Manno D, et al. Human cytomegalovirus infant infection adversely affects growth and development in maternally HIV-exposed and unexposed infants in Zambia.

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#### **Acknowledgements**

This work was supported by the European Commission (grant ADAT-number SANTE/ 2006/129-131). AZ is grant holder and MB study coordinator. AZ and MB are supported by the European and Developing Countries Clinical Trials Partnership (EDCTP grants REMOX, PANACEA and TB-NEAT), Netherlands; UK Medical Research Council (MRC); UBS Optimus Foundation, Switzerland; University College London Hospitals Comprehensive Biomedical Research Centre (UCLH-CBRC); and the UCLH National Health Service (NHS) Foundation Trust. KM is supported by the Commonwealth Scholarship Commission, U.K.

#### **Author details**

Matthew Bates1,2\*, Kunda Musonda1,2,3 and Alimuddin Zumla2

\*Address all correspondence to: matthew.bates@ucl.ac.uk

1 UNZA-UCLMS Research and Training Programme and HerpeZ, University of Zambia School of Medicine/University Teaching Hospital, Lusaka, Zambia

2 University College London (UCL) Medical School, Department of Infection, Centre for In‐ fectious Diseases and International Health, Royal Free Hospital, London, UK

3 London School of Hygiene and Tropical Medicine (LSHTM), Department of Infectious Tropical Diseases, Pathogen Molecular Biology Unit, London, UK

#### **References**


[3] Gompels UA, Larke N, Sanz-Ramos M, Bates M, Musonda K, Manno D, et al. Human cytomegalovirus infant infection adversely affects growth and development in maternally HIV-exposed and unexposed infants in Zambia. Clin Infect Dis. 2012 Feb 1;54(3):434-42.

between 2010 and 2020 [154]; The number of transplant recipients is also set to increase, as the

This work was supported by the European Commission (grant ADAT-number SANTE/ 2006/129-131). AZ is grant holder and MB study coordinator. AZ and MB are supported by the European and Developing Countries Clinical Trials Partnership (EDCTP grants REMOX, PANACEA and TB-NEAT), Netherlands; UK Medical Research Council (MRC); UBS Optimus Foundation, Switzerland; University College London Hospitals Comprehensive Biomedical Research Centre (UCLH-CBRC); and the UCLH National Health Service (NHS) Foundation

1 UNZA-UCLMS Research and Training Programme and HerpeZ, University of Zambia

2 University College London (UCL) Medical School, Department of Infection, Centre for In‐

3 London School of Hygiene and Tropical Medicine (LSHTM), Department of Infectious

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Trust. KM is supported by the Commonwealth Scholarship Commission, U.K.

Matthew Bates1,2\*, Kunda Musonda1,2,3 and Alimuddin Zumla2

School of Medicine/University Teaching Hospital, Lusaka, Zambia

Tropical Diseases, Pathogen Molecular Biology Unit, London, UK

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capacity of tertiary care centres develops and improves.

**Acknowledgements**

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**Chapter 3**

**Management of**

A.L. Corona-Nakamura and

http://dx.doi.org/10.5772/56141

M.J. Arias-Merino

**1. Introduction**

in these patients.

can reach 82% [1-5].

virus) [6].

**CMV-Associated Diseases**

**in Immunocompromised Patients**

Additional information is available at the end of the chapter

management of cytomegalovirus (CMV) infection and disease.

properly cited.

Among the great advances that have been achieved in infectious diseases has been on the

This chapter describe an overview of the clinical manifestations of CMV diseases that are in immunocompromised patients, including patients with human immunodeficiency virus infection / Acquired Immunodeficiency Syndrome (HIV / AIDS), organ transplant recipients, bone marrow transplant recipients, and individuals receiving immunosuppressive therapy or chemotherapeutic agents. We also present the conditions for the development of CMV disease

In the overall population, the seroprevalence of CMV (IgG) is 30 to 100%. CMV disease is a major cause of death in bone marrow and organ transplant recipients and persons with AIDS. In adult patients with cancer and leukemia (except T cell leukemia) who have not undergone transplantation, the frequency of CMV disease is lower than 3%, but mortality

The direct clinical effects of CMV are CMV viral syndrome and end-organ diseases. The indirect effects include superinfections caused by bacteria (eg: *Listeria* or *Pseudomonas*), fungi (eg: *Aspergillus, Pneumocystis jiroveci, Cryptococcus*) or other viruses (herpes zoster, Epstein Barr

and reproduction in any medium, provided the original work is properly cited.

© 2013 Corona-Nakamura and Arias-Merino; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is

© 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

**Chapter 3**

## **Management of CMV-Associated Diseases in Immunocompromised Patients**

A.L. Corona-Nakamura and M.J. Arias-Merino

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/56141

#### **1. Introduction**

Among the great advances that have been achieved in infectious diseases has been on the management of cytomegalovirus (CMV) infection and disease.

This chapter describe an overview of the clinical manifestations of CMV diseases that are in immunocompromised patients, including patients with human immunodeficiency virus infection / Acquired Immunodeficiency Syndrome (HIV / AIDS), organ transplant recipients, bone marrow transplant recipients, and individuals receiving immunosuppressive therapy or chemotherapeutic agents. We also present the conditions for the development of CMV disease in these patients.

In the overall population, the seroprevalence of CMV (IgG) is 30 to 100%. CMV disease is a major cause of death in bone marrow and organ transplant recipients and persons with AIDS. In adult patients with cancer and leukemia (except T cell leukemia) who have not undergone transplantation, the frequency of CMV disease is lower than 3%, but mortality can reach 82% [1-5].

The direct clinical effects of CMV are CMV viral syndrome and end-organ diseases. The indirect effects include superinfections caused by bacteria (eg: *Listeria* or *Pseudomonas*), fungi (eg: *Aspergillus, Pneumocystis jiroveci, Cryptococcus*) or other viruses (herpes zoster, Epstein Barr virus) [6].

properly cited.

© 2013 Corona-Nakamura and Arias-Merino; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

### **2. Terminology**

CMV Infection is defined as the detection of the CMV virus by antibodies in blood or the detection of this virus by polymerase chain reaction (PCR), or antigens in any body fluid or tissue specimen, but the infected patient not show any clinical symptoms caused by the virus [2,4,7].

Prophylactic therapy involves administration of oral valganciclovir or intravenous ganciclovir at-risk patients, such as patients with CMV IgG serostatus negative (D+/R-) or when the recipients need anti-rejection therapy, such as anti-thymocyte globulin (ATG) or anti-lym‐

Management of CMV-Associated Diseases in Immunocompromised Patients

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43

CMV infections may be more frequently caused by reactivation of the virus in the recipient rather than a primary infection. Approximately 30% of seronegative recipients with seropos‐ itive stem cell donors (D+/R-) develop primary CMV infection, whereas reactivation occurs in

According the guidelines by Tomblyn *et al* 2009, HSCT recipients at risk for post transplant CMV disease (all CMV-seropositive HSCT recipients, and all CMV-seronegative recipients with a CMV seropositive donor) should have a CMV disease prevention program from the time of transplantation until at least 100 days after HSCT, using prophylaxis or preemptive

**1.** To all allogeneic HSCT recipients with evidence of CMV infection for CMV DNA, and this strategy is preferred over prophylaxis therapy for D+/R-. Administer induction doses: Valganciclovir 900 mg twice daily or ganciclovir I.V. 5mg/kg every 12 hours for 7-14 days. Maintenance doses: for another 3-4 weeks until the test is negative or resolution of

**2.** CMV seropositive autologous HSCT recipients with high risk for CMV replication or disease, for example patients who had total body irradiation, and patients who have received alemtuzumab within 6 months prior to HSCT. Administer induction doses: Valganciclovir 900 mg twice daily or ganciclovir I.V. 5mg/kg every 12 hours for 7 days.Maintenance doses: for another 3-4 weeks until the test is negative or resolution of symptoms. Note: Continue screening for CMV reactivation and re-treat if screening tests

**2.** All patients receiving steroids for graft-versus-host disease (GVHD), steroid use, low CD4

, and use of grafts from CMV-seronegative donors in CMV-seropositive

phocyte globulins (ALGs) [2].

**3. The role of immunosuppression**

treatment for allogeneic recipients.

symptoms.

**3.1. CMV disease in transplantation recipients**

*3.1.1. Hemopoietic Stem Cell Transplantation (HSCT)*

about 80% who were seropositive before transplantation [8,10].

A preemptive strategy against CMV replication (<100 days post-HSCT):

become positive after discontinuation of therapy [11].

Preemptive therapy > 100 days post-HSCT for:

**1.** Allogeneic HSCT recipients.

counts <50/mm3

recipients.

CMV Disease is the presence of CMV infection, evident as:

**CMV Syndrome**, a clinical condition characterized by fever ≥ 101 ºF (≥ 38.3ºC) at least twice within 7 days, muscle pain, leukopenia ≤ 3500/μl, neutropenia ≤ 1,500/μl, atypical lymphocy‐ tosis ≥ 5% and/or thrombocytopenia < 100,000/μl [7] or…

**CMV Disease with Organ and Tissue involvement**. Clinical presentations [3,4,6] include pneumonitis, gastrointestinal disease (e.g., gastritis, colitis, esophageal ulcers), hepatitis, pancreatitis, nephritis, cystitis, myocarditis, retinitis, central nervous system disease (e.g., meningitis, polyradiculitis, encephalitis, transverse myelitis, Guillain-Barré Syndrome, peripheral neuropathy), thrombocytopenia, hemolytic anemia, adrenalitis, disseminated disease [2].

Primary infection is defined as the detection of CMV infection in an individual previously found to be CMV seronegative. In the case transplanted patients, when the recipient with CMV seronegative (IgG and IgM) receives blood products or a graft from a donor CMV seropositive IgG (D+/R-). The appearance of de novo specific antibodies in a seronegative patient may also be acceptable for the diagnosis of CMV [2,7].

Secondary (Reactivation) infection occurs with the reactivation of endogenous latent CMV, in a CMV seropositive patient, who has (cancer, chronic lymphocytic leukemia, solid organ transplantation, or bone marrow transplantation) with diminished immunity after immuno‐ suppressive therapy or a patient with HIV. The recipient before transplantation is seropositive for CMV (IgG) and the donor is seronegative to CMV (IgG and IgM) (D-/R+) [2,4,8,9]. Reacti‐ vation or reinfection again initiates an IgM response. The IgG appears within a few weeks of the IgM rise (4).

Superinfection can occur when the recipient receives a graft or blood products from a donor who is CMV seropositive with different strain of CMV (D+/R+) [2].

Preemptive therapy consists on to monitor weekly by CMV blood PCR to immunocompro‐ mised patients and if the test becomes positive, they will be treated with antiviral, irrespective of clinical symptoms. This type of therapy is used in patients with solid organ transplant (specifically with serotypes D+/R +, D-/ R+ and D-/R-), hemopoietic stem cell transplantation, and patient with chronic lymphocytic leukemia who received alemtuzumab, each group of patients has specific guidelines for this type of therapy. Following a study in which CMV DNA was found in 83% of liver transplant recipients at a mean of 13 days before the onset of symptomatic CMV infection, it has become apparent that the preemptive therapy decreases the morbidity and mortality of CMV infection [2].

Prophylactic therapy involves administration of oral valganciclovir or intravenous ganciclovir at-risk patients, such as patients with CMV IgG serostatus negative (D+/R-) or when the recipients need anti-rejection therapy, such as anti-thymocyte globulin (ATG) or anti-lym‐ phocyte globulins (ALGs) [2].

#### **3. The role of immunosuppression**

**2. Terminology**

42 Manifestations of Cytomegalovirus Infection

[2,4,7].

disease [2].

the IgM rise (4).

CMV Infection is defined as the detection of the CMV virus by antibodies in blood or the detection of this virus by polymerase chain reaction (PCR), or antigens in any body fluid or tissue specimen, but the infected patient not show any clinical symptoms caused by the virus

**CMV Syndrome**, a clinical condition characterized by fever ≥ 101 ºF (≥ 38.3ºC) at least twice within 7 days, muscle pain, leukopenia ≤ 3500/μl, neutropenia ≤ 1,500/μl, atypical lymphocy‐

**CMV Disease with Organ and Tissue involvement**. Clinical presentations [3,4,6] include pneumonitis, gastrointestinal disease (e.g., gastritis, colitis, esophageal ulcers), hepatitis, pancreatitis, nephritis, cystitis, myocarditis, retinitis, central nervous system disease (e.g., meningitis, polyradiculitis, encephalitis, transverse myelitis, Guillain-Barré Syndrome, peripheral neuropathy), thrombocytopenia, hemolytic anemia, adrenalitis, disseminated

Primary infection is defined as the detection of CMV infection in an individual previously found to be CMV seronegative. In the case transplanted patients, when the recipient with CMV seronegative (IgG and IgM) receives blood products or a graft from a donor CMV seropositive IgG (D+/R-). The appearance of de novo specific antibodies in a seronegative patient may also

Secondary (Reactivation) infection occurs with the reactivation of endogenous latent CMV, in a CMV seropositive patient, who has (cancer, chronic lymphocytic leukemia, solid organ transplantation, or bone marrow transplantation) with diminished immunity after immuno‐ suppressive therapy or a patient with HIV. The recipient before transplantation is seropositive for CMV (IgG) and the donor is seronegative to CMV (IgG and IgM) (D-/R+) [2,4,8,9]. Reacti‐ vation or reinfection again initiates an IgM response. The IgG appears within a few weeks of

Superinfection can occur when the recipient receives a graft or blood products from a donor

Preemptive therapy consists on to monitor weekly by CMV blood PCR to immunocompro‐ mised patients and if the test becomes positive, they will be treated with antiviral, irrespective of clinical symptoms. This type of therapy is used in patients with solid organ transplant (specifically with serotypes D+/R +, D-/ R+ and D-/R-), hemopoietic stem cell transplantation, and patient with chronic lymphocytic leukemia who received alemtuzumab, each group of patients has specific guidelines for this type of therapy. Following a study in which CMV DNA was found in 83% of liver transplant recipients at a mean of 13 days before the onset of symptomatic CMV infection, it has become apparent that the preemptive therapy decreases

who is CMV seropositive with different strain of CMV (D+/R+) [2].

the morbidity and mortality of CMV infection [2].

CMV Disease is the presence of CMV infection, evident as:

tosis ≥ 5% and/or thrombocytopenia < 100,000/μl [7] or…

be acceptable for the diagnosis of CMV [2,7].

#### **3.1. CMV disease in transplantation recipients**

#### *3.1.1. Hemopoietic Stem Cell Transplantation (HSCT)*

CMV infections may be more frequently caused by reactivation of the virus in the recipient rather than a primary infection. Approximately 30% of seronegative recipients with seropos‐ itive stem cell donors (D+/R-) develop primary CMV infection, whereas reactivation occurs in about 80% who were seropositive before transplantation [8,10].

According the guidelines by Tomblyn *et al* 2009, HSCT recipients at risk for post transplant CMV disease (all CMV-seropositive HSCT recipients, and all CMV-seronegative recipients with a CMV seropositive donor) should have a CMV disease prevention program from the time of transplantation until at least 100 days after HSCT, using prophylaxis or preemptive treatment for allogeneic recipients.

A preemptive strategy against CMV replication (<100 days post-HSCT):


Preemptive therapy > 100 days post-HSCT for:


Administer induction doses: Valganciclovir 900 mg twice daily or ganciclovir I.V. 5mg/kg every 12 hours for 7-14 days.

There is an Intermediate risk of CMV disease with D+/R+ or D-/R+ combinations and a low

Management of CMV-Associated Diseases in Immunocompromised Patients

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45

In kidney transplant patients, 8-18 % will have CMV infection. The clinical presentations may be asymptomatic, fever or affect the transplanted organ, as a glomerulopathy or nephritis

Amongst liver transplant patients, 29% present CMV infection manifesting as CMV hepa‐

Amongst heart transplant patients, 25% present with CMV infection manifesting as myocar‐ ditis [2,7]. Of the patients transplanted kidney-pancreas, 50% will present CMV infection

22% of patients with transplanted small bowel will have CMV infection affecting the trans‐

Around 39% of patients with heart-lung transplants can be expected to have CMV infection,

Antiviral prophylaxis is highly effective in preventing CMV disease in transplanted recip‐ ients, particularly in D+/R- patients. However, late-onset CMV disease may occur after 100 days or several years after transplantation, coinciding with discontinuation of antivi‐ ral prophylaxis. Among kidney and kidney-pancreas transplant recipients, late-onset CMV disease was documented in 47% of D+/R- patients, 12% of D+/R+ patients, 7% of D-/R+ patients, and 4% of D-/R- patients [16]. One study reported that up to 27% of highrisk (CMV D+/R-) liver and kidney transplantation recipients who received oral ganciclo‐ vir prophylaxis for 3 months developed late-onset CMV disease after the completion of antiviral prophylaxis. CMV retinitis and CMV colitis tend to be later manifestations of

In a systematic review, CMV disease occurred in 2.6% and 9.9% of SOT recipients receiving valganciclovir as preemptive therapy and prophylaxis, respectively. In patients receiving valganciclovir prophylaxis, the incidence of early-onset (≤ 90 days posttransplant) CMV disease was 0.8% and 1.2% in all patients (D+/R+, D-/R+) and D+/R- patients, respectively. In the prophylactic group, the incidence of late-onset (>90 days posttransplant) CMV disease rose up to 8.9 % and 17.7 % in all patients and D+/R-, respectively. Ninety-two percent of the patients with CMV disease in the prophylactic group were late-onset disease. No patients developed late-onset CMV disease in preemptive group. Late-onset CMV disease is a complication observed uniquely with valganciclovir prophylaxis, particularly in D+/R- patients, but not with

The rejection rate was 10.8% in SOT recipients who receiving preemptive therapy. The overall rejection was 17.6% in the prophylactic studies. Fifteen patients (3.9%) of 380 patients in preemptive group had graft loss. In prophylactic studies the graft loss rate was 2.5%. The patients who receiving preemptive therapy, 28.5% developed opportunistic infections. In

risk when the donor and recipient are CMV seronegative [2,7].

usually affecting the transplanted pancreas [2,7].

usually affecting the lung causing pneumonitis [2,7].

disease or a clinical presentation atypical [2,16].

*3.1.4. Late CMV disease in solid organ transplanted patients*

[2,7,15].

titis [2,6].

planted bowel [2,7].

preemptive therapy [17].

Maintenance doses: for another 3-4 weeks until the test is negative or resolution of symp‐ toms [11].

Prophylactic therapy can be recommended for all allogeneic recipients (from engraftment to 100 days after HSCT), this therapy is not recommended for seropositive autologous recipients, except the patient is at high risk as recipients unrelated, patient with human leucocyte antigen (HLA) system-mismatched or in patients who used the alemtuzumab and are candidates for HSCT. The induction: valganciclovir 450 mg twice daily for 5-7 days. Maintenance: Daily until day 100 after HSCT [8,11,12].

Before the introduction of specific prophylaxis, the risk of CMV disease was reported to be up to 58% in of the allogeneic stem cell transplant seropositive recipients, the clinical presentation more likely was pneumonia with mortality to 94 % [2,7,8,13]. The incidence of CMV pneumonia after autologous bone marrow transplantation and peripheral blood SCT ranges from 1% to 6% [8,14].

Gastrointestinal disease is the most common disease, after CMV pneumonia, which can escape blood-based surveillance by PCR in approximately 25 % of patients. There is presently no consensus on how to use molecular methods to diagnose CMV gastrointestinal and pneumonia disease because there are no data on what level of CMV DNA in brochoalveolar lavage (BAL) fluid or tissue that correlates best with CMV disease. The gastrointestinal disease is treated with antiviral alone. The treatment of CMV pneumonia includes the antiviral and intravenous immunoglobulin. CMV retinitis and encephalitis are rare complications [8,12].

#### *3.1.2. Late CMV disease in HSCT patients*

Late CMV disease (after 100 days) occurs in 15% to 20% of seropositive allograft recipients, and it occurs between months 4 and 12 after HSCT, with a mortality rate of 46%. Risk factors for late CMV disease include CMV infection during the first 3 months after transplantation, chronic graft-versus-host disease (GVHD), CD4 counts less 50 per mm3, and undetectable CMV-specific T-cell immunity [8,12].

#### *3.1.3. Solid Organ Transplant (SOT)*

CMVinfectionismostcommonduringthefirst3to12weeksaftertransplantation,this isbecause in this period is more intense immunosuppression to prevent rejection [2].

There is a high risk of CMV disease when a seronegative receptor receives an organ from a seropositive individual [Donor+/Recipient- (D+/R-)]. Up to 85% of SOT recipients with CMV D+/R- serologic status develop primary CMV disease, with the prophylactic therapy reducing CMV disease to 22% [2].

Other high risk factors are biologic agents used for induction therapy or rejection treatment. These include T lymphocyte (OKT3) monoclonal antibody, ATG, ALGs, or high doses of corticosteroids [2,7].

There is an Intermediate risk of CMV disease with D+/R+ or D-/R+ combinations and a low risk when the donor and recipient are CMV seronegative [2,7].

In kidney transplant patients, 8-18 % will have CMV infection. The clinical presentations may be asymptomatic, fever or affect the transplanted organ, as a glomerulopathy or nephritis [2,7,15].

Amongst liver transplant patients, 29% present CMV infection manifesting as CMV hepa‐ titis [2,6].

Amongst heart transplant patients, 25% present with CMV infection manifesting as myocar‐ ditis [2,7]. Of the patients transplanted kidney-pancreas, 50% will present CMV infection usually affecting the transplanted pancreas [2,7].

22% of patients with transplanted small bowel will have CMV infection affecting the trans‐ planted bowel [2,7].

Around 39% of patients with heart-lung transplants can be expected to have CMV infection, usually affecting the lung causing pneumonitis [2,7].

#### *3.1.4. Late CMV disease in solid organ transplanted patients*

Administer induction doses: Valganciclovir 900 mg twice daily or ganciclovir I.V. 5mg/kg

Maintenance doses: for another 3-4 weeks until the test is negative or resolution of symp‐

Prophylactic therapy can be recommended for all allogeneic recipients (from engraftment to 100 days after HSCT), this therapy is not recommended for seropositive autologous recipients, except the patient is at high risk as recipients unrelated, patient with human leucocyte antigen (HLA) system-mismatched or in patients who used the alemtuzumab and are candidates for HSCT. The induction: valganciclovir 450 mg twice daily for 5-7 days. Maintenance: Daily until

Before the introduction of specific prophylaxis, the risk of CMV disease was reported to be up to 58% in of the allogeneic stem cell transplant seropositive recipients, the clinical presentation more likely was pneumonia with mortality to 94 % [2,7,8,13]. The incidence of CMV pneumonia after autologous bone marrow transplantation and peripheral blood SCT ranges from 1% to

Gastrointestinal disease is the most common disease, after CMV pneumonia, which can escape blood-based surveillance by PCR in approximately 25 % of patients. There is presently no consensus on how to use molecular methods to diagnose CMV gastrointestinal and pneumonia disease because there are no data on what level of CMV DNA in brochoalveolar lavage (BAL) fluid or tissue that correlates best with CMV disease. The gastrointestinal disease is treated with antiviral alone. The treatment of CMV pneumonia includes the antiviral and intravenous

Late CMV disease (after 100 days) occurs in 15% to 20% of seropositive allograft recipients, and it occurs between months 4 and 12 after HSCT, with a mortality rate of 46%. Risk factors for late CMV disease include CMV infection during the first 3 months after transplantation, chronic graft-versus-host disease (GVHD), CD4 counts less 50 per mm3, and undetectable

CMVinfectionismostcommonduringthefirst3to12weeksaftertransplantation,this isbecause

There is a high risk of CMV disease when a seronegative receptor receives an organ from a seropositive individual [Donor+/Recipient- (D+/R-)]. Up to 85% of SOT recipients with CMV D+/R- serologic status develop primary CMV disease, with the prophylactic therapy reducing

Other high risk factors are biologic agents used for induction therapy or rejection treatment. These include T lymphocyte (OKT3) monoclonal antibody, ATG, ALGs, or high doses of

immunoglobulin. CMV retinitis and encephalitis are rare complications [8,12].

in this period is more intense immunosuppression to prevent rejection [2].

every 12 hours for 7-14 days.

44 Manifestations of Cytomegalovirus Infection

day 100 after HSCT [8,11,12].

*3.1.2. Late CMV disease in HSCT patients*

CMV-specific T-cell immunity [8,12].

*3.1.3. Solid Organ Transplant (SOT)*

CMV disease to 22% [2].

corticosteroids [2,7].

toms [11].

6% [8,14].

Antiviral prophylaxis is highly effective in preventing CMV disease in transplanted recip‐ ients, particularly in D+/R- patients. However, late-onset CMV disease may occur after 100 days or several years after transplantation, coinciding with discontinuation of antivi‐ ral prophylaxis. Among kidney and kidney-pancreas transplant recipients, late-onset CMV disease was documented in 47% of D+/R- patients, 12% of D+/R+ patients, 7% of D-/R+ patients, and 4% of D-/R- patients [16]. One study reported that up to 27% of highrisk (CMV D+/R-) liver and kidney transplantation recipients who received oral ganciclo‐ vir prophylaxis for 3 months developed late-onset CMV disease after the completion of antiviral prophylaxis. CMV retinitis and CMV colitis tend to be later manifestations of disease or a clinical presentation atypical [2,16].

In a systematic review, CMV disease occurred in 2.6% and 9.9% of SOT recipients receiving valganciclovir as preemptive therapy and prophylaxis, respectively. In patients receiving valganciclovir prophylaxis, the incidence of early-onset (≤ 90 days posttransplant) CMV disease was 0.8% and 1.2% in all patients (D+/R+, D-/R+) and D+/R- patients, respectively. In the prophylactic group, the incidence of late-onset (>90 days posttransplant) CMV disease rose up to 8.9 % and 17.7 % in all patients and D+/R-, respectively. Ninety-two percent of the patients with CMV disease in the prophylactic group were late-onset disease. No patients developed late-onset CMV disease in preemptive group. Late-onset CMV disease is a complication observed uniquely with valganciclovir prophylaxis, particularly in D+/R- patients, but not with preemptive therapy [17].

The rejection rate was 10.8% in SOT recipients who receiving preemptive therapy. The overall rejection was 17.6% in the prophylactic studies. Fifteen patients (3.9%) of 380 patients in preemptive group had graft loss. In prophylactic studies the graft loss rate was 2.5%. The patients who receiving preemptive therapy, 28.5% developed opportunistic infections. In contrast, prophylactic studies reported the proportion of patients with opportunistic infections was 7.8%. The mortality was 8.2% from four preemptive studies, and 4.4% in prophylactic studies [17].

**3.4. CMV disease in patients with haematological malignancies and solid tumours**

CMV disease is potentiated by drugs that cause profound cell-mediated immunosuppression, such as fludarabine (which depresses CD4 T-lymphocytes), high-dose cyclophosphamide, high-dose of steroids and granulocyte transfusions from donors who have CMV disease, and with the use of metotrexate, cyclosporine, alemtuzumab (anti-CD52 MoAb) and rituximab (anti-CD20 MoAb). The mortality rate among the patients with leukemia, myelodysplastic syndrome or lymphoma was 82%, and the 63% of the fatal cases was due to, relapse of leukemia, refractory leukemia, or that these patients were in accelerated or blast phase [1,23].

Management of CMV-Associated Diseases in Immunocompromised Patients

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47

In 2001, serious CMV disease, (primarily pneumonia) was found at autopsy in 17%-75% of patients dying with T cell leukemia. Mortality was higher among patients who had lympho‐

Chronic lymphocytic leukemia (CLL) is a disease of progressive with an accumulation of clonal B lymphocytes in peripheral blood, marrow, and lymphoid organs. This is generally incurable, except the patients who receive an allogeneic cell transplant, and it is the most common form of adult leukemia in Western countries. Patients with CLL have impaired humoral and cellular immunity [24-26]. Current treatments for patients with CLL include monoclonal antibodies

Alentuzumab is a recombinant humanized, anti-CD52 monoclonal antibody with significant activity in CLL, including frudarabine-refractory disease. CD52 is a glycoprotein of unknown function that is expressed on the surfaces of normal and malignant B and T lymphocytes. Binding of alemtuzumab to CD52 on lymphocytes induces complement-dependent cytotox‐ icity, antibody-dependent cell-mediated cytotoxicity (which results in a rapid and profound reduction of lymphocytes, and this produces viral replication and reactivation CMV) and

Viral infections often are presented at the third week after the initiation of alemtuzumab, which coincides with the nadir in T-cell numbers. The CMV reactivation is the most common opportunistic infection observed in alemtuzumab-treated patients and it is observed at the beginning of the 4 - 6 weeks of alemtuzumab [30]. O´Brien *et al* estimated the incidence of CMV reactivation ranges from 4 to 30 %. This incidence typically refers to symptomatic CMV infection [9,24,28,31,32]. CMV pneumonitis was reported 0.8 %, and CMV-related death 0.2 %. CMV reactivation which frequently presents as fever of unknown origin or respiratory

Among the recommendations on the use of alemtuzumab in the patient with CLL, is moni‐ toring for opportunistic infections, such as CMV reactivation, theses management guidelines are referred by Osterborg A *et al*, 2009, and O'Brien *et al* 2006 for monitoring and treating of

*3.4.1. Guidelines on the management of CMV reactivation in patients with chronic lymphocytic*

penia [1].

*leukemia treated with alemtuzumab*

symptoms [9,24,28,31,33].

CMV reactivation, such as:

(eg. rituximab and alemtuzumab) among others [9,27].

direct cytotoxicity (likely apoptotic cell death) [9,24,25,27-29].

Updated management guidelines for using alemtuzumab in CLL.

#### *3.1.5. Recurrent CMV disease*

Recurrent CMV disease may occur in up to 25% of SOTR (2). Predictive factors include the type of organ transplant, CMV DNA in plasma at day 21, negative CMV IgG serostatus D+/Rat start of treatment and therapy for acute rejection (18). The rate of recurrent CMV disease for lung transplant recipients was 38.5%, for kidney 14.6%, for heart 11.8%, and for liver transplant recipients was 0%. The yearly risk of recurrent CMV disease was 24.4% for patients with persistent CMV DNAemia in plasma at day 21 versus 8.8% for those eradicated at day 21 [18].

CMV recurrence may be related to incomplete suppression of viral replication or the duration of treatment (often 2-4 weeks) may have been insufficient. Some authors suggest treatment for 3 months for pneumonitis, retinitis and gastrointestinal CMV disease. Plasma levels of CMV DNA should influence the therapy duration [2]. Weekly monitoring until eradication is recommended [18].

#### **3.2. CMV disease in patients with HIV/AIDS**

CMV infection was one of the most important opportunistic infection in HIV-infected patients before the introduction of the highly active antiretroviral therapy. Approximately 40% of HIVinfected patients with advanced disease suffered from one of several manifestations of CMV infection during their life. Colitis is the second most common presentation of CMV disease after CMV retinitis (4). It is related to the degree of T-cell impairment, being most common in patients with CD4+ T-cell counts bellow 50-100 cells/μl [3,19].

#### **3.3. CMV disease in patients with rheumatic diseases**

The incidence of CMV in rheumatic patients was 50% for systemic lupus erythematosus (SLE), 10% for dermatomyositis, 8.8% for microscopic polyangitis, and less than 5% for rheumatoid arthritis, rheumatoid vasculitis, Behcet´s disease, Chung-Strauss syndrome. The mortality rates CMV disease were 20-75% rheumatological disease depending on the type. The fever was the most common symptom, respiratory symptoms were the second most common, followed by gastrointestinal symptoms. Visual disturbance was observed in one patient [20].

CMV infection was most common among patients under strong immunosupressive thera‐ py (eg: 500-1000 mg pulsed methylprednisolone per day, 60-100 mg oral prednisolone, or intravenous or oral cyclophosphamide within a year before CMV diagnosis [19]. The effect of corticosteroid involves derangement of T lymphocyte and monocyte/macrophage functions, and blockade of the production of cytokines such as TNF-α. Cyclophosphamide suppresses lymphocyte proliferation and function which increasing the risk of CMV reactivation and replication [1,20-22].

#### **3.4. CMV disease in patients with haematological malignancies and solid tumours**

contrast, prophylactic studies reported the proportion of patients with opportunistic infections was 7.8%. The mortality was 8.2% from four preemptive studies, and 4.4% in prophylactic

Recurrent CMV disease may occur in up to 25% of SOTR (2). Predictive factors include the type of organ transplant, CMV DNA in plasma at day 21, negative CMV IgG serostatus D+/Rat start of treatment and therapy for acute rejection (18). The rate of recurrent CMV disease for lung transplant recipients was 38.5%, for kidney 14.6%, for heart 11.8%, and for liver transplant recipients was 0%. The yearly risk of recurrent CMV disease was 24.4% for patients with persistent CMV DNAemia in plasma at day 21 versus 8.8% for those eradicated at day 21 [18].

CMV recurrence may be related to incomplete suppression of viral replication or the duration of treatment (often 2-4 weeks) may have been insufficient. Some authors suggest treatment for 3 months for pneumonitis, retinitis and gastrointestinal CMV disease. Plasma levels of CMV DNA should influence the therapy duration [2]. Weekly monitoring until eradication is

CMV infection was one of the most important opportunistic infection in HIV-infected patients before the introduction of the highly active antiretroviral therapy. Approximately 40% of HIVinfected patients with advanced disease suffered from one of several manifestations of CMV infection during their life. Colitis is the second most common presentation of CMV disease after CMV retinitis (4). It is related to the degree of T-cell impairment, being most common in

The incidence of CMV in rheumatic patients was 50% for systemic lupus erythematosus (SLE), 10% for dermatomyositis, 8.8% for microscopic polyangitis, and less than 5% for rheumatoid arthritis, rheumatoid vasculitis, Behcet´s disease, Chung-Strauss syndrome. The mortality rates CMV disease were 20-75% rheumatological disease depending on the type. The fever was the most common symptom, respiratory symptoms were the second most common, followed by gastrointestinal symptoms. Visual disturbance was observed in one patient [20].

CMV infection was most common among patients under strong immunosupressive thera‐ py (eg: 500-1000 mg pulsed methylprednisolone per day, 60-100 mg oral prednisolone, or intravenous or oral cyclophosphamide within a year before CMV diagnosis [19]. The effect of corticosteroid involves derangement of T lymphocyte and monocyte/macrophage functions, and blockade of the production of cytokines such as TNF-α. Cyclophosphamide suppresses lymphocyte proliferation and function which increasing the risk of CMV

T-cell counts bellow 50-100 cells/μl [3,19].

studies [17].

*3.1.5. Recurrent CMV disease*

46 Manifestations of Cytomegalovirus Infection

recommended [18].

patients with CD4+

**3.2. CMV disease in patients with HIV/AIDS**

**3.3. CMV disease in patients with rheumatic diseases**

reactivation and replication [1,20-22].

CMV disease is potentiated by drugs that cause profound cell-mediated immunosuppression, such as fludarabine (which depresses CD4 T-lymphocytes), high-dose cyclophosphamide, high-dose of steroids and granulocyte transfusions from donors who have CMV disease, and with the use of metotrexate, cyclosporine, alemtuzumab (anti-CD52 MoAb) and rituximab (anti-CD20 MoAb). The mortality rate among the patients with leukemia, myelodysplastic syndrome or lymphoma was 82%, and the 63% of the fatal cases was due to, relapse of leukemia, refractory leukemia, or that these patients were in accelerated or blast phase [1,23].

In 2001, serious CMV disease, (primarily pneumonia) was found at autopsy in 17%-75% of patients dying with T cell leukemia. Mortality was higher among patients who had lympho‐ penia [1].

#### *3.4.1. Guidelines on the management of CMV reactivation in patients with chronic lymphocytic leukemia treated with alemtuzumab*

Chronic lymphocytic leukemia (CLL) is a disease of progressive with an accumulation of clonal B lymphocytes in peripheral blood, marrow, and lymphoid organs. This is generally incurable, except the patients who receive an allogeneic cell transplant, and it is the most common form of adult leukemia in Western countries. Patients with CLL have impaired humoral and cellular immunity [24-26]. Current treatments for patients with CLL include monoclonal antibodies (eg. rituximab and alemtuzumab) among others [9,27].

Alentuzumab is a recombinant humanized, anti-CD52 monoclonal antibody with significant activity in CLL, including frudarabine-refractory disease. CD52 is a glycoprotein of unknown function that is expressed on the surfaces of normal and malignant B and T lymphocytes. Binding of alemtuzumab to CD52 on lymphocytes induces complement-dependent cytotox‐ icity, antibody-dependent cell-mediated cytotoxicity (which results in a rapid and profound reduction of lymphocytes, and this produces viral replication and reactivation CMV) and direct cytotoxicity (likely apoptotic cell death) [9,24,25,27-29].

Viral infections often are presented at the third week after the initiation of alemtuzumab, which coincides with the nadir in T-cell numbers. The CMV reactivation is the most common opportunistic infection observed in alemtuzumab-treated patients and it is observed at the beginning of the 4 - 6 weeks of alemtuzumab [30]. O´Brien *et al* estimated the incidence of CMV reactivation ranges from 4 to 30 %. This incidence typically refers to symptomatic CMV infection [9,24,28,31,32]. CMV pneumonitis was reported 0.8 %, and CMV-related death 0.2 %. CMV reactivation which frequently presents as fever of unknown origin or respiratory symptoms [9,24,28,31,33].

Updated management guidelines for using alemtuzumab in CLL.

Among the recommendations on the use of alemtuzumab in the patient with CLL, is moni‐ toring for opportunistic infections, such as CMV reactivation, theses management guidelines are referred by Osterborg A *et al*, 2009, and O'Brien *et al* 2006 for monitoring and treating of CMV reactivation, such as:


If the CMV PCR two consecutive positive results obtained 1 week apart, it should start preemptive therapy with intravenous ganciclovir or oral valganciclovir or when CMV reactivation becomes symptomatic or viremia increase, alemtuzumab therapy should be interrupted and anti-CMV therapy to be started (Figure 1) [9,24,25,28].

The antiviral is administrated 900 mg twice daily for 21 days, or continue with the maintenance dose 900 mg twice daily until the CMV PCR is negative or until you have 2 consecutive negative results [9,24,25,28].

The pre-emptive treatment prevents the occurrence of potentially life-threatening infec‐ tious diseases, and the initiation of anti-CMV treatment avoids the interruption of alem‐ tuzumab [31].

Another modality is the anti-CMV prophylaxis in CLL patients receiving alemtuzumab, is with valganciclovir 450 mg twice daily. The prophylaxis is administrated entire duration of Alemtuzumab therapy and until 2 months after end the therapy and the frequency of CMV PCR is every 2 weeks. The valganciclovir prophylaxis may be used in patients with elevated risk for CMV reactivation [9, 28]. Patients on prophylactic valganciclovir had a lower rate of CMV activation compared with valacyclovir (3% vs 24%) among patients being treated with an alemtuzumab-based regimen [26,32]

presence of extrapulmonary CMV disease could suggest the diagnosis of CMV pneumonia [37]. The symptoms are fever, nonproductive cough, dyspnea, or worsening dyspnea that progresses to hypoxemia, and necessitates assisted mechanical ventilation [6]. It can include extrapulmonary CMV disease (gastrointestinal or retinitis) [37]. The signs can include normal

**Figure 1.** Guidelines on the Management in Cytomegalovirus Monitoring for Patients with Chronic Lymphocytic Leu‐

Asymptomatic CMV reactivation

> Symptomatic CMV reactivation

 CMV positive

Empirical treatment

Management of CMV-Associated Diseases in Immunocompromised Patients

Preemptive therapy

9

49

Treatment for CMV infection for 14-21 days: Ganciclovir (I.V. 5mg/kg every 12 hours or Oral Valganciclovir 900 mg every 12 hours; Foscarnet can be added

http://dx.doi.org/10.5772/56141

On chest radiograph the infiltrates are usually bilateral and may be interstitial and diffuse (figure 2), or nodular, or alveolar and occasionally small pleural effusions [37]. The most common manifestations of CMVp on conventional radiographs are parenchymal consolida‐

In patients having AIDS, the most frequent finding was dense consolidation and mass-like opacities. The most frequent computed tomography (CT) pattern in immunocompromised patients without AIDS was ground-glass opacities which were bilateral patchy, diffuse distribution. Other findings included poorly-defined small nodules and consolidation.

Coinfections were other potentially life-threatening infections that occurred within 90 days of

the episode of CMVp. These can contribute to death in patients with fatal CMVp [23].

breath sounds at auscultation or basal crepitations [6].

Running Title

Fever unknown origen

Prophylaxis Valganciclovir 900 mg daily

Basal status CMV Weekly monitoring with PCR or pp65 antigen assay

kemia Treated with Alemtuzumab

PCR, polymerase chain reaction; IV, via intravenous.

CMV positive

PCR or pp65 antigen assay

Unresponsive to antibiotics therapy

tion and multiple nodules measuring less 5 mm in diameter [38].

Interlobular septal thickening and pleural effusion [38,39].

#### **3.5. CMV infection in patients with inflammatory bowel disease**

CMV disease is seen in patients under treatment with azathioprine alone or with 5-aminosa‐ licylic acid, steroids, and/or infliximab, or 6-mercaptopurine, or leukocytapheresis. Crohn disease (CD) was underlying disease in 77% of cases possibly because immunosuppression is more common in CD compared to Ulcerative colitis (UC) [6].

#### **4. Clinical presentations of CMV disease**

#### **4.1. CMV Pneumonia (CMVp)**

"CMVp" is defined as the occurrence of clinical and radiographic evidence of pneumonia, in association with the isolation of CMV in BAL, or lung-tissue specimens or with the identifi‐ cation of CMV in lung tissue by histopathology, immunohistochemistry or PCR [1].

CMVp represents a major cause of morbidity and mortality in highly immunosuppressed patients, the clinical presentation resembles *Pneumocystis jiroveci* pneumonia (PCP), the

9

PCR, polymerase chain reaction; IV, via intravenous.

Running Title

**1.** Baseline CMV serology prior to therapy of the patient

weeks after alemtuzumab discontinuation [34-36].

interrupted and anti-CMV therapy to be started (Figure 1) [9,24,25,28].

**3.5. CMV infection in patients with inflammatory bowel disease**

more common in CD compared to Ulcerative colitis (UC) [6].

**4. Clinical presentations of CMV disease**

**4.1. CMV Pneumonia (CMVp)**

should start [9,24,25,27,28,31]

48 Manifestations of Cytomegalovirus Infection

an alemtuzumab-based regimen [26,32]

results [9,24,25,28].

tuzumab [31].

**2.** If the fever unresponsive to antibacterial agents and test not available should be presumed to be CMV reactivation and the alemtuzumab should discontinue and antiviral therapy

**3.** Monitoring CMV reactivation by weekly PCR during therapy, and every 2 weeks for 6

If the CMV PCR two consecutive positive results obtained 1 week apart, it should start preemptive therapy with intravenous ganciclovir or oral valganciclovir or when CMV reactivation becomes symptomatic or viremia increase, alemtuzumab therapy should be

The antiviral is administrated 900 mg twice daily for 21 days, or continue with the maintenance dose 900 mg twice daily until the CMV PCR is negative or until you have 2 consecutive negative

The pre-emptive treatment prevents the occurrence of potentially life-threatening infec‐ tious diseases, and the initiation of anti-CMV treatment avoids the interruption of alem‐

Another modality is the anti-CMV prophylaxis in CLL patients receiving alemtuzumab, is with valganciclovir 450 mg twice daily. The prophylaxis is administrated entire duration of Alemtuzumab therapy and until 2 months after end the therapy and the frequency of CMV PCR is every 2 weeks. The valganciclovir prophylaxis may be used in patients with elevated risk for CMV reactivation [9, 28]. Patients on prophylactic valganciclovir had a lower rate of CMV activation compared with valacyclovir (3% vs 24%) among patients being treated with

CMV disease is seen in patients under treatment with azathioprine alone or with 5-aminosa‐ licylic acid, steroids, and/or infliximab, or 6-mercaptopurine, or leukocytapheresis. Crohn disease (CD) was underlying disease in 77% of cases possibly because immunosuppression is

"CMVp" is defined as the occurrence of clinical and radiographic evidence of pneumonia, in association with the isolation of CMV in BAL, or lung-tissue specimens or with the identifi‐

CMVp represents a major cause of morbidity and mortality in highly immunosuppressed patients, the clinical presentation resembles *Pneumocystis jiroveci* pneumonia (PCP), the

cation of CMV in lung tissue by histopathology, immunohistochemistry or PCR [1].

**Figure 1.** Guidelines on the Management in Cytomegalovirus Monitoring for Patients with Chronic Lymphocytic Leu‐ kemia Treated with Alemtuzumab

presence of extrapulmonary CMV disease could suggest the diagnosis of CMV pneumonia [37]. The symptoms are fever, nonproductive cough, dyspnea, or worsening dyspnea that progresses to hypoxemia, and necessitates assisted mechanical ventilation [6]. It can include extrapulmonary CMV disease (gastrointestinal or retinitis) [37]. The signs can include normal breath sounds at auscultation or basal crepitations [6].

On chest radiograph the infiltrates are usually bilateral and may be interstitial and diffuse (figure 2), or nodular, or alveolar and occasionally small pleural effusions [37]. The most common manifestations of CMVp on conventional radiographs are parenchymal consolida‐ tion and multiple nodules measuring less 5 mm in diameter [38].

In patients having AIDS, the most frequent finding was dense consolidation and mass-like opacities. The most frequent computed tomography (CT) pattern in immunocompromised patients without AIDS was ground-glass opacities which were bilateral patchy, diffuse distribution. Other findings included poorly-defined small nodules and consolidation. Interlobular septal thickening and pleural effusion [38,39].

Coinfections were other potentially life-threatening infections that occurred within 90 days of the episode of CMVp. These can contribute to death in patients with fatal CMVp [23].

HSCT and lung transplant recipients who develop CMVp or infection have an increased risk for subsequent invasive aspergillosis [23].

A study of cancer patients receiving chemotherapy placed the incidence of CMVp below 3%, in patients with head and neck cancers, nasopharyngeal cancer (NPC), hypopharyngeal cancer (HPC), lung cancer, lymphoma and rectal cancer. The chemotherapy regimen used was cisplatin, 5-FU, fluorouracil, leucovorin and etoposide. As the incidence is low, prophylactic

Management of CMV-Associated Diseases in Immunocompromised Patients

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51

Cascio *et al*. [6] reported that the 85% of patients with inflammatory bowel disease who developed CMVp were on treatment with thiopurines (azathioprine and 6-mercaptopurine) when they developed CMVp. The mean length of treatment with azathioprine before the appearance of respiratory symptoms was 19 months, with 6-mercaptopurine was 18 months, infliximab was 10 days to 3 weeks, and cyclosporine was 3 days. These patients had hemato‐ logical findings such as pancytopenia, lymphopenia, neutropenia, leucopenia, severe anemia, hemophagocytic lymphohistiocytosis or thrombocytopenia. Symptoms lasted from 2 days to

Symptoms range from low-grade fever, weight loss, anorexia, abdominal pain, and bloody diarrhea to a fulminant colitis. In HIV patients can have present esophageal ulcer, esophagitis, gastritis, duodenitis, jejunal and ileal perforation, peritonitis secondary, odynophagia, and bowel obstruction. GI CMV disease is estimated to affect about 20% of adults with AIDS, and it can be involved all parts of the gastrointestinal tract, but the colon and esophagus are the most common sites [4, 41]. CMV infection of the endothelial cells and ensuing vasculitis may play a role in the development of thrombosis, local ischemia and ulceration of the gastroin‐

Refers to the presence of the virus in the colon in sites of inflamed tissue. Within patients with severe ulcerative colitis (UC), CMV disease may occur more commonly in patients over age 55, and in patients treated with steroids. Steroids produce suppression of CMV-specific T-cell function. Infliximab has not been associated with an increased risk of CMV in patients with

TheprevalenceofCMVcolitisinresectedIBDspecimensrangedfrom0to22%[39],theprevalence assessedusingCMVDNAincolonbiopsywas81%inUCpatients,and66%prevalence inCrohn ´s disease patients [3]. Domenech *et al*, showed a prevalence of colonic CMV of 32% in patients

CMV colitis has occurred primarily in patients with pre-existing UC, with documented disease for as long as 20-30 years [3]. Another theory was that CMV was an innocent bystander in IBD colitis. This may reflect infection with nonpathogenic genotypes. The challenge is differenti‐ ating the innocent bystanders from the pathogenic strains, so most patients are treated with antivirals, as the possible cost of delaying antiviral therapy is colectomy or even death. Refractory IBD colitis have been associated with CMV inclusions bodies, and these patients

therapy was not recommended [5].

**4.2. CMV gastrointestinal (GI) diseases**

inflammatory bowel disease (IBD) [4].

have a colectomy rate of 62% and a mortality rate of 44% [3].

with steroid-refractory UC [10].

1 month [6,23].

testinal mucosa [41].

*4.2.1. CMV colitis*

In allogeneic bone marrow transplant recipients, the incidence of CMVp is 20-35% and the mortality is up to 50% [40]. IV ganciclovir is given concurrently with immune serum globulin or hyperimmune globulin. In autologous bone marrow transplant recipients, the incidence of CMVp is 2% [9,23]. The mortality rate from CMVp in patients with HSCT was 100% [23].

**Figure 2.** Bilateral interstitial pneumonia caused by CMV in a renal transplant recipient

In solid organ transplantation, the incidence of CMVp is 17 to 90 % [23].

In adults with leukemia, the frequency of CMVp was 0.4%, 2.2%, 2.3%, and 2.5% in patients with myelodysplastic syndrome, acute myelogenous leukemia (AML), chronic myelogenous leukemia (CML), and acute lymphocytic leukemia (ALL) respectively and 8.8% and 11% in patients with chronic lymphocytic leukemia (CLL) and lymphoblastic lymphoma. The median duration of time from the diagnosis of leukemia to the occurrence of CMVp ranged from 6 months and 9 months in patients with AML and ALL, respectively, to 25 months and 54 months in patients with CML, and CLL respectively [1,23].

The CMVp among patients with leukemia, lymphoma and myelodysplastic syndrome, the mortality rate was 57%, and the death occurred 15 (2-36) days after onset of illness. Among patients treated before the occurrence of respiratory failure, the mortality rate was 48%. When therapy was initiated after the occurrence of respiratory failure that required mechanical ventilation, the mortality rate was 57-100 % [1,23].

Chemaly *et al*. [23] observed that, the incidence of CMVp among adults with lymphoma was 0.6-1.2%. In the 92% of the patients, chemotherapy had been administered to the patients within 6 months before the onset of CMVp. Essentially, these patients with lymphoma were treated with rituximab or alemtuzumab [23].

A study of cancer patients receiving chemotherapy placed the incidence of CMVp below 3%, in patients with head and neck cancers, nasopharyngeal cancer (NPC), hypopharyngeal cancer (HPC), lung cancer, lymphoma and rectal cancer. The chemotherapy regimen used was cisplatin, 5-FU, fluorouracil, leucovorin and etoposide. As the incidence is low, prophylactic therapy was not recommended [5].

Cascio *et al*. [6] reported that the 85% of patients with inflammatory bowel disease who developed CMVp were on treatment with thiopurines (azathioprine and 6-mercaptopurine) when they developed CMVp. The mean length of treatment with azathioprine before the appearance of respiratory symptoms was 19 months, with 6-mercaptopurine was 18 months, infliximab was 10 days to 3 weeks, and cyclosporine was 3 days. These patients had hemato‐ logical findings such as pancytopenia, lymphopenia, neutropenia, leucopenia, severe anemia, hemophagocytic lymphohistiocytosis or thrombocytopenia. Symptoms lasted from 2 days to 1 month [6,23].

#### **4.2. CMV gastrointestinal (GI) diseases**

Symptoms range from low-grade fever, weight loss, anorexia, abdominal pain, and bloody diarrhea to a fulminant colitis. In HIV patients can have present esophageal ulcer, esophagitis, gastritis, duodenitis, jejunal and ileal perforation, peritonitis secondary, odynophagia, and bowel obstruction. GI CMV disease is estimated to affect about 20% of adults with AIDS, and it can be involved all parts of the gastrointestinal tract, but the colon and esophagus are the most common sites [4, 41]. CMV infection of the endothelial cells and ensuing vasculitis may play a role in the development of thrombosis, local ischemia and ulceration of the gastroin‐ testinal mucosa [41].

#### *4.2.1. CMV colitis*

HSCT and lung transplant recipients who develop CMVp or infection have an increased risk

In allogeneic bone marrow transplant recipients, the incidence of CMVp is 20-35% and the mortality is up to 50% [40]. IV ganciclovir is given concurrently with immune serum globulin or hyperimmune globulin. In autologous bone marrow transplant recipients, the incidence of CMVp is 2% [9,23]. The mortality rate from CMVp in patients with HSCT was 100% [23].

**Figure 2.** Bilateral interstitial pneumonia caused by CMV in a renal transplant recipient

in patients with CML, and CLL respectively [1,23].

ventilation, the mortality rate was 57-100 % [1,23].

with rituximab or alemtuzumab [23].

In solid organ transplantation, the incidence of CMVp is 17 to 90 % [23].

In adults with leukemia, the frequency of CMVp was 0.4%, 2.2%, 2.3%, and 2.5% in patients with myelodysplastic syndrome, acute myelogenous leukemia (AML), chronic myelogenous leukemia (CML), and acute lymphocytic leukemia (ALL) respectively and 8.8% and 11% in patients with chronic lymphocytic leukemia (CLL) and lymphoblastic lymphoma. The median duration of time from the diagnosis of leukemia to the occurrence of CMVp ranged from 6 months and 9 months in patients with AML and ALL, respectively, to 25 months and 54 months

The CMVp among patients with leukemia, lymphoma and myelodysplastic syndrome, the mortality rate was 57%, and the death occurred 15 (2-36) days after onset of illness. Among patients treated before the occurrence of respiratory failure, the mortality rate was 48%. When therapy was initiated after the occurrence of respiratory failure that required mechanical

Chemaly *et al*. [23] observed that, the incidence of CMVp among adults with lymphoma was 0.6-1.2%. In the 92% of the patients, chemotherapy had been administered to the patients within 6 months before the onset of CMVp. Essentially, these patients with lymphoma were treated

for subsequent invasive aspergillosis [23].

50 Manifestations of Cytomegalovirus Infection

Refers to the presence of the virus in the colon in sites of inflamed tissue. Within patients with severe ulcerative colitis (UC), CMV disease may occur more commonly in patients over age 55, and in patients treated with steroids. Steroids produce suppression of CMV-specific T-cell function. Infliximab has not been associated with an increased risk of CMV in patients with inflammatory bowel disease (IBD) [4].

TheprevalenceofCMVcolitisinresectedIBDspecimensrangedfrom0to22%[39],theprevalence assessedusingCMVDNAincolonbiopsywas81%inUCpatients,and66%prevalence inCrohn ´s disease patients [3]. Domenech *et al*, showed a prevalence of colonic CMV of 32% in patients with steroid-refractory UC [10].

CMV colitis has occurred primarily in patients with pre-existing UC, with documented disease for as long as 20-30 years [3]. Another theory was that CMV was an innocent bystander in IBD colitis. This may reflect infection with nonpathogenic genotypes. The challenge is differenti‐ ating the innocent bystanders from the pathogenic strains, so most patients are treated with antivirals, as the possible cost of delaying antiviral therapy is colectomy or even death. Refractory IBD colitis have been associated with CMV inclusions bodies, and these patients have a colectomy rate of 62% and a mortality rate of 44% [3].

CMV reactivation exacerbates disease severity in those with active intestinal inflammation. Patients with IBD have impaired NK cell activity and defects in mucosal immunity, which may enhance susceptibility to CMV reactivation). Patients described as "steroid-refractory" show CMV detectable by immunohistochemistry (IHC) in 20%-40% of both endoscopic biopsies and colectomy specimens. CMV DNA was detectable in the colon of up to 60% of patients in the same study [4].

CMV colitis is rare in patients with Crohn´s disease or mild-moderate ulcerative colitis. In patients with severe and/or steroid-refractory ulcerative colitis, the possibility of a concurrent CMV infection causing or worsening the colitis is considered, especially when patients are on immunosuppressive medications. Local reactivation of CMV can be detected in actively inflamed colonic tissue in about 30% of cases [3].

CMV has tropism for dysplastic colonic tissue (adenomas and adenocarcinomas) and may play a significant role in cancer progression. The association of CMV infection with dysplasia progression in IBD patients increases the risk of developing colorectal cancer [3].

*4.2.2. CMV hepatitis*

*4.2.3. CMV pancreatitis*

**4.3. CMV retinitis**

 

between 9 week and 1 year after initial antiviral [3].

**Figure 3.** Algorithm for management of suspected CMV colitis in patients with IBD [4]

CMV IgG+ or IgM+

Severa/Steroid-Refractory Colitis

Tissue IHC or Blood CMV PCR

In patients having AIDS, relapse of CMV gastrointestinal disease in AIDS patients can occur

Is defined by findings such as fever, vomiting, with hepatomegaly with hepatalgia, and atypical lymphocytosis may be approximately 50%, elevated bilirubin and/or enzyme levels, and detection of CMV by histopathologic analysis within the liver tissue is needed [13,42].

Requires the detection of CMV infection by immunohistochemical analysis together with the identification in a pancreatic biopsy. Detection of CMV by PCR alone is insufficient for diagnosis of CMV pancreatitis because it can imply the presence of transient viremia [42].

Retinitis can appear more than 6 months after solid organ transplantation, mainly heart transplant recipients. The patients can be asymptomatic, or they may experience blurring of vision, scotomata, or decreased visual acuity. Fundoscopy often reveals the diagnosis [2]. In HIV-infected patients, retinitis is the single most common manifestation of CMV disease, accounting for 85% of all cases. In developing countries, CMV retinitis is still the most frequent cause of visual loss in HIV-infected patients. Accordingly, the incidence of CMV retinitis,

CMV disease active

IV Ganciclovir or oral Valganciclovir Considerar stopping immunosuppressant if severe CMV infection

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The diagnosis includes:

Endoscopic findings comprise patchy erythema, exudates, microerosions, edematous mu‐ cosa, or deep ulcers and pseudotumor [42]. These findings can be very difficult to distin‐ guish from severe IBD colitis [39]. CMV colitis may exclusively affect the right colon in up to 30% of cases [3].

CMV antigenemia is being supplanted by leukocyte CMV PCR. A "cut off" level of viremia for distinguishing infection from disease is required for CMV colitis in patients with IBD [4]. Higher CMV viral loads correlate with symptomatic disease [3]. Most studies in patients with IBD have reported a correlation between identification of CMV by PCR in blood, and colonic detection in tissue by hematoxylin and eosin (H&E) or IHC [3,4]. IHC improves histological sensitivity. It uses monoclonal antibodies, identifying infected cells in the colon. Sensibility ranges 78%-93% [4]. PCR of colonic tissue can be used to detect viral DNA [5]. The GI disease can occur even if there is no detection of CMV in the blood [10].

The European Crohn´s and Colitis Organization guidelines (2009) [4]: its authors recommend the use of tissue PCR or IHC in investigating for CMV in cases of IBD.

Guidelines from the American College of Gastroenterology, and the European Crohn´s & Colitis Organization (ECCO) recommend treatment with antivirals when CMV is detected by blood PCR or IHC on colonic biopsies, which must be performed in all patients with severe colitis refractory to immunosuppressive therapy. They do not recommend colonic PCR because they give false positive results. Likewise, they recommend the discontinuation of immunosuppressive agents only in cases of severe systemic CMV disease[4].

Treatment with antiviral therapy has allowed some patients with severe colitis to avoid colectomy despite poor response to conventional IBD therapies. CMV colitis is usually treated with ganciclovir, foscarnet, valganciclovir, or cidofovir. The recommended dosage is for at least 3-6 weeks. The "response rate" in patients with steroid-refractory disease who have reactivation of CMV is 72% (range 50%-100%) (figure 3) [3, 4].

 **Figure 3.** Algorithm for management of suspected CMV colitis in patients with IBD [4]

In patients having AIDS, relapse of CMV gastrointestinal disease in AIDS patients can occur between 9 week and 1 year after initial antiviral [3].

#### *4.2.2. CMV hepatitis*

CMV reactivation exacerbates disease severity in those with active intestinal inflammation. Patients with IBD have impaired NK cell activity and defects in mucosal immunity, which may enhance susceptibility to CMV reactivation). Patients described as "steroid-refractory" show CMV detectable by immunohistochemistry (IHC) in 20%-40% of both endoscopic biopsies and colectomy specimens. CMV DNA was detectable in the colon of up to 60% of patients in the

CMV colitis is rare in patients with Crohn´s disease or mild-moderate ulcerative colitis. In patients with severe and/or steroid-refractory ulcerative colitis, the possibility of a concurrent CMV infection causing or worsening the colitis is considered, especially when patients are on immunosuppressive medications. Local reactivation of CMV can be detected in actively

CMV has tropism for dysplastic colonic tissue (adenomas and adenocarcinomas) and may play a significant role in cancer progression. The association of CMV infection with dysplasia

Endoscopic findings comprise patchy erythema, exudates, microerosions, edematous mu‐ cosa, or deep ulcers and pseudotumor [42]. These findings can be very difficult to distin‐ guish from severe IBD colitis [39]. CMV colitis may exclusively affect the right colon in

CMV antigenemia is being supplanted by leukocyte CMV PCR. A "cut off" level of viremia for distinguishing infection from disease is required for CMV colitis in patients with IBD [4]. Higher CMV viral loads correlate with symptomatic disease [3]. Most studies in patients with IBD have reported a correlation between identification of CMV by PCR in blood, and colonic detection in tissue by hematoxylin and eosin (H&E) or IHC [3,4]. IHC improves histological sensitivity. It uses monoclonal antibodies, identifying infected cells in the colon. Sensibility ranges 78%-93% [4]. PCR of colonic tissue can be used to detect viral DNA [5]. The GI disease

The European Crohn´s and Colitis Organization guidelines (2009) [4]: its authors recommend

Guidelines from the American College of Gastroenterology, and the European Crohn´s & Colitis Organization (ECCO) recommend treatment with antivirals when CMV is detected by blood PCR or IHC on colonic biopsies, which must be performed in all patients with severe colitis refractory to immunosuppressive therapy. They do not recommend colonic PCR because they give false positive results. Likewise, they recommend the discontinuation of

Treatment with antiviral therapy has allowed some patients with severe colitis to avoid colectomy despite poor response to conventional IBD therapies. CMV colitis is usually treated with ganciclovir, foscarnet, valganciclovir, or cidofovir. The recommended dosage is for at least 3-6 weeks. The "response rate" in patients with steroid-refractory disease who have

progression in IBD patients increases the risk of developing colorectal cancer [3].

can occur even if there is no detection of CMV in the blood [10].

reactivation of CMV is 72% (range 50%-100%) (figure 3) [3, 4].

the use of tissue PCR or IHC in investigating for CMV in cases of IBD.

immunosuppressive agents only in cases of severe systemic CMV disease[4].

same study [4].

The diagnosis includes:

up to 30% of cases [3].

inflamed colonic tissue in about 30% of cases [3].

Is defined by findings such as fever, vomiting, with hepatomegaly with hepatalgia, and atypical lymphocytosis may be approximately 50%, elevated bilirubin and/or enzyme levels, and detection of CMV by histopathologic analysis within the liver tissue is needed [13,42].

#### *4.2.3. CMV pancreatitis*

Requires the detection of CMV infection by immunohistochemical analysis together with the identification in a pancreatic biopsy. Detection of CMV by PCR alone is insufficient for diagnosis of CMV pancreatitis because it can imply the presence of transient viremia [42].

#### **4.3. CMV retinitis**

Retinitis can appear more than 6 months after solid organ transplantation, mainly heart transplant recipients. The patients can be asymptomatic, or they may experience blurring of vision, scotomata, or decreased visual acuity. Fundoscopy often reveals the diagnosis [2]. In HIV-infected patients, retinitis is the single most common manifestation of CMV disease, accounting for 85% of all cases. In developing countries, CMV retinitis is still the most frequent cause of visual loss in HIV-infected patients. Accordingly, the incidence of CMV retinitis, which is the most common CMV disease among HIV patients, decreased from 17.1 ⁄ 100 patient years to 5.6 ⁄ 100 patient-years [2, 43].

Running Title

**Figure 5.** Reference [43]

*4.5.1. CMV Nephritis*

*4.5.2. CMV Cystitis*

**4.6. CMV myocarditis**

5) [2,43].

*4.4.2. CMV ventriculoencephalitis*

**4.5. CMV genitourinary diseases**

patient with symptoms of cystitis [42].

of CMV by PCR alone is insufficient for this diagnosis [42].

This occurs rarely. It presents with changes in mental function. Multiple small, peri-ventricular lesions of the brain are detected following brain magnetic resonance imaging (arrow) (figure

Management of CMV-Associated Diseases in Immunocompromised Patients

It can be defined by the detection of CMV infection by immunohistochemical analysis together with the identification of histological features of CMV infection in a kidney biopsy. Detection

This CMV disease is defined by detection of CMV by immunohistochemical together with identification of conventional histological features of CMV in a bladder biopsy obtained from

This occurs most frequently in heart transplant recipients. This infection is defined by the detection of CMV infection by immunohistochemical analysis together with the identification of conventional histological features of CMV infection in a heart biopsy specimen and CMV

17

55

http://dx.doi.org/10.5772/56141

**Figure 4.** Reference [43]

CMV retinitis in a patient with AIDS appears as an arcuate zone of retinitis with extensive haemorrhages and optic disk swelling (figure 4) [43].

#### **4.4. CMV neurological diseases**

#### *4.4.1. CMV Guillain–Barré Syndrome (GBS)*

GBS has become the most frequent cause of acute flaccid paralysis in Western countries, following the near-elimination of poliomyelitis. The current annual incidence is estimated to be 0.75–2 cases ⁄ 100 000 population. Infectious agents have been suggested as possible triggers of GBS, as some form of respiratory or gastrointestinal infection precedes nearly two-thirds of GBS cases. Infection with CMV is the most common antecedent virus infection, as identified by the presence of IgM antibodies in 10–15% of patients at the onset of GBS. However, antiviral therapy is currently not recommended in cases of GBS, since the disease is considered to be post infectious. Recently, the presence of CMV DNA has been demonstrated in almost onethird of serum and cerebrospinal fluid samples from GBS patients who were positive for CMVspecific antibodies at the onset of the neurological disease [43]

17

**Figure 5.** Reference [43]

Running Title

which is the most common CMV disease among HIV patients, decreased from 17.1 ⁄ 100 patient

CMV retinitis in a patient with AIDS appears as an arcuate zone of retinitis with extensive

GBS has become the most frequent cause of acute flaccid paralysis in Western countries, following the near-elimination of poliomyelitis. The current annual incidence is estimated to be 0.75–2 cases ⁄ 100 000 population. Infectious agents have been suggested as possible triggers of GBS, as some form of respiratory or gastrointestinal infection precedes nearly two-thirds of GBS cases. Infection with CMV is the most common antecedent virus infection, as identified by the presence of IgM antibodies in 10–15% of patients at the onset of GBS. However, antiviral therapy is currently not recommended in cases of GBS, since the disease is considered to be post infectious. Recently, the presence of CMV DNA has been demonstrated in almost onethird of serum and cerebrospinal fluid samples from GBS patients who were positive for CMV-

years to 5.6 ⁄ 100 patient-years [2, 43].

54 Manifestations of Cytomegalovirus Infection

**Figure 4.** Reference [43]

**4.4. CMV neurological diseases**

*4.4.1. CMV Guillain–Barré Syndrome (GBS)*

haemorrhages and optic disk swelling (figure 4) [43].

specific antibodies at the onset of the neurological disease [43]

#### *4.4.2. CMV ventriculoencephalitis*

This occurs rarely. It presents with changes in mental function. Multiple small, peri-ventricular lesions of the brain are detected following brain magnetic resonance imaging (arrow) (figure 5) [2,43].

#### **4.5. CMV genitourinary diseases**

#### *4.5.1. CMV Nephritis*

It can be defined by the detection of CMV infection by immunohistochemical analysis together with the identification of histological features of CMV infection in a kidney biopsy. Detection of CMV by PCR alone is insufficient for this diagnosis [42].

#### *4.5.2. CMV Cystitis*

This CMV disease is defined by detection of CMV by immunohistochemical together with identification of conventional histological features of CMV in a bladder biopsy obtained from patient with symptoms of cystitis [42].

#### **4.6. CMV myocarditis**

This occurs most frequently in heart transplant recipients. This infection is defined by the detection of CMV infection by immunohistochemical analysis together with the identification of conventional histological features of CMV infection in a heart biopsy specimen and CMV PCR. Detection of CMV by PCR alone is insufficient for the diagnosis of CMV myocarditis [42]. There is an association between CMV and left ventricular dysfunction [2].

The most typical signs of HPS are fever ≥ 38.3ºC) and splenomegaly associated with pancyto‐ penia (affecting ≥ 2 cell lineages in peripheral blood), hepatic enzyme abnormalities, hyper‐ triglyceridemia or hypofibrinogenemia are common features of HPS. The diagnostic sensitivity of hypertriglyceridemia, hypofibrinogenemia and splenomegaly may be about 50%, but the diagnostic sensitivity of low NK cell activity and soluble CD25 levels approaches 100%. The histopathologic features are not pathognomonic. The most prominent feature is proliferation of histiocytes and hemophagocytosis in bone marrow, spleen, or lymph nodes,

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57

Hemoglobin ≤ 9 g/dl, or platelets count < 100,000/μl, or neutrophil count < 1,000/μl

Therapy includes corticosteroids, cyclosporine, withdrawal of the immunosuppressant treatment, intravenous immunoglobulins (0.4g/ kg /day for 5 days) and antiviral treatment. The mortality rates are 30-40 % [45]. The hemophagocytic syndrome should be considered if a patient has fever of unknown origin, pancytopenia and multiorgan dysfunction [45,48,49].

From the Infectious Disease Department Specialities Hospital, West Medical Center, Institu‐

[1] Nguyen Q, Estey E, Radd I, Rolston K, Kantarjian H, Jacobson K, et al. Cytomegalo‐ virus Pneumonia in Adults with Leukemia: An Emerging Problem. *CID* 2001; 32:

5. Hypertriglyceridemia: Fasting triglycerides ≥ 265 mg/dl (> 3 mmol/l)

10. Soluble CD25 (soluble interleukin-2 receptor) ≥ 2,400 U/ml

8. Hemophagocytosis demonstrated in bone marrow, spleen, or lymph node

with no evidence of malignancy [34,45,48,49].

3. Absence of malignancy 4. Cytopenia of ≥ 2 cell lines

6. Hypofibrinogenemia: < 1.5 g/l 7. Serum ferritin > 500 μg/l

**Table 1.** HLH-2004 Diagnostic criteria, References [48,49]

A.L. Corona-Nakamura and M.J. Arias-Merino

to Mexicano del Seguro Social, Guadalajara, Jalisco, México

**Author details**

**References**

539-45.

9. Low or absent NK cell activity) ≥ 2,400 U/ml

1. Fever: ≥ 101 ºF (≥ 38.3ºC) for more than a week 2. Splenomegaly: about 3 cm below the costal arch

#### **4.7. CMV vasculopathy**

The CMV vasculopathy is considered to be an inflammatory disease. CMV and others organisms such as *Chlamydia pneumoniae*, Epstein Barr virus, herpes simplex virus-1, *Myco‐ plasma pneumoniae* and *Helicobacter pylori* are implicated, but evidence is strongest with CMV and *Chlamydia pneumoniae*. There is a correlation between CMV seropositivity and the presence of atherosclerosis, restenosis following and coronary angioplasty and transplant vascular sclerosis. CMV antigens and nucleic acids have been detected in atherosclerotic lesions in the different layers of the human aorta. Patients suffering from acute myocardial infarction have been found to develop CMV antigenaemia, reflecting either a primary infection or reactivation of a latent infection [44].

CMV infects cells in vessels on endotelial cells, smooth muscle cells and macrophages contribute to the slow progression and aggravation of atherosclerosis. The virus may also contribute to coronary thrombosis [44].

#### **4.8. CMV associated Hemophagocytic Syndrome (HPS)**

CMV hemophagocytic syndrome, also referred as macrophage activation syndrome (MAS) or haemophagocytic lymphohistiocytosis (HLH), is a reactive disorder, characterized by gener‐ alized histiocytic proliferation, with marked hemophagocytosis. This syndrome was first described by Risdull et al in 1979 in transplant patients [45]. There are two forms of HPS, familial erytrocytic lymphohistiocytosis and the secondary or reactive HPS [34,46,47].

Reactive or secondary HPS may develop during systemic infections, immunodeficiencies or malignancies. Infection-associated hemophagocytic syndrome (IAHS) is observed with viral infections (CMV, Epstein Barr virus, human herpes virus 8, human herpes virus 6, Parvovirus B19 or BK polyoma virus), bacterial infections (*Escherichia coli* and *Mycobacterium*), fungal infection (*Histoplasma, Pneumocystis*, and *Penicillum marneffei*), parasitic infections (toxoplas‐ mosis, leishmaniasis or babesiosis). HPS may also develop as a complication of malignancies such as T-cell lymphomas and metastatic carcinomas. Secundary HPS to inflammatory/ autoimmune disorders, including systemic lupus erythematosus, rheumatoid arthritis and Still´s disease, or due anticonvulsants such as phenytoin and carbamazepine [34,45,46].

Cytomegalovirus has been associated with haemophagocytic syndrome in healthy patients, patients with inflammatory bowel diseases, rheumatological diseases, and transplant recipi‐ ents [45,47].

The pathophysiology of HPS is not completely understood there is an activation of lympho‐ histiocytic tissue secondary to hypercytokinemia derived from the activation of T lymphocytes and activated macrophages, causing fever, shock, and organ dysfunction [48,4]).

The HLH (Henter, 2004), (Emmenegger, 2005) diagnostic criteria are shown in Table 1,

The most typical signs of HPS are fever ≥ 38.3ºC) and splenomegaly associated with pancyto‐ penia (affecting ≥ 2 cell lineages in peripheral blood), hepatic enzyme abnormalities, hyper‐ triglyceridemia or hypofibrinogenemia are common features of HPS. The diagnostic sensitivity of hypertriglyceridemia, hypofibrinogenemia and splenomegaly may be about 50%, but the diagnostic sensitivity of low NK cell activity and soluble CD25 levels approaches 100%. The histopathologic features are not pathognomonic. The most prominent feature is proliferation of histiocytes and hemophagocytosis in bone marrow, spleen, or lymph nodes, with no evidence of malignancy [34,45,48,49].

1. Fever: ≥ 101 ºF (≥ 38.3ºC) for more than a week 2. Splenomegaly: about 3 cm below the costal arch 3. Absence of malignancy 4. Cytopenia of ≥ 2 cell lines Hemoglobin ≤ 9 g/dl, or platelets count < 100,000/μl, or neutrophil count < 1,000/μl 5. Hypertriglyceridemia: Fasting triglycerides ≥ 265 mg/dl (> 3 mmol/l) 6. Hypofibrinogenemia: < 1.5 g/l 7. Serum ferritin > 500 μg/l 8. Hemophagocytosis demonstrated in bone marrow, spleen, or lymph node 9. Low or absent NK cell activity) ≥ 2,400 U/ml 10. Soluble CD25 (soluble interleukin-2 receptor) ≥ 2,400 U/ml

**Table 1.** HLH-2004 Diagnostic criteria, References [48,49]

Therapy includes corticosteroids, cyclosporine, withdrawal of the immunosuppressant treatment, intravenous immunoglobulins (0.4g/ kg /day for 5 days) and antiviral treatment. The mortality rates are 30-40 % [45]. The hemophagocytic syndrome should be considered if a patient has fever of unknown origin, pancytopenia and multiorgan dysfunction [45,48,49].

#### **Author details**

PCR. Detection of CMV by PCR alone is insufficient for the diagnosis of CMV myocarditis [42].

The CMV vasculopathy is considered to be an inflammatory disease. CMV and others organisms such as *Chlamydia pneumoniae*, Epstein Barr virus, herpes simplex virus-1, *Myco‐ plasma pneumoniae* and *Helicobacter pylori* are implicated, but evidence is strongest with CMV and *Chlamydia pneumoniae*. There is a correlation between CMV seropositivity and the presence of atherosclerosis, restenosis following and coronary angioplasty and transplant vascular sclerosis. CMV antigens and nucleic acids have been detected in atherosclerotic lesions in the different layers of the human aorta. Patients suffering from acute myocardial infarction have been found to develop CMV antigenaemia, reflecting either a primary infection or reactivation

CMV infects cells in vessels on endotelial cells, smooth muscle cells and macrophages contribute to the slow progression and aggravation of atherosclerosis. The virus may also

CMV hemophagocytic syndrome, also referred as macrophage activation syndrome (MAS) or haemophagocytic lymphohistiocytosis (HLH), is a reactive disorder, characterized by gener‐ alized histiocytic proliferation, with marked hemophagocytosis. This syndrome was first described by Risdull et al in 1979 in transplant patients [45]. There are two forms of HPS,

Reactive or secondary HPS may develop during systemic infections, immunodeficiencies or malignancies. Infection-associated hemophagocytic syndrome (IAHS) is observed with viral infections (CMV, Epstein Barr virus, human herpes virus 8, human herpes virus 6, Parvovirus B19 or BK polyoma virus), bacterial infections (*Escherichia coli* and *Mycobacterium*), fungal infection (*Histoplasma, Pneumocystis*, and *Penicillum marneffei*), parasitic infections (toxoplas‐ mosis, leishmaniasis or babesiosis). HPS may also develop as a complication of malignancies such as T-cell lymphomas and metastatic carcinomas. Secundary HPS to inflammatory/ autoimmune disorders, including systemic lupus erythematosus, rheumatoid arthritis and Still´s disease, or due anticonvulsants such as phenytoin and carbamazepine [34,45,46].

Cytomegalovirus has been associated with haemophagocytic syndrome in healthy patients, patients with inflammatory bowel diseases, rheumatological diseases, and transplant recipi‐

The pathophysiology of HPS is not completely understood there is an activation of lympho‐ histiocytic tissue secondary to hypercytokinemia derived from the activation of T lymphocytes

and activated macrophages, causing fever, shock, and organ dysfunction [48,4]).

The HLH (Henter, 2004), (Emmenegger, 2005) diagnostic criteria are shown in Table 1,

familial erytrocytic lymphohistiocytosis and the secondary or reactive HPS [34,46,47].

There is an association between CMV and left ventricular dysfunction [2].

**4.7. CMV vasculopathy**

56 Manifestations of Cytomegalovirus Infection

of a latent infection [44].

ents [45,47].

contribute to coronary thrombosis [44].

**4.8. CMV associated Hemophagocytic Syndrome (HPS)**

A.L. Corona-Nakamura and M.J. Arias-Merino

From the Infectious Disease Department Specialities Hospital, West Medical Center, Institu‐ to Mexicano del Seguro Social, Guadalajara, Jalisco, México

#### **References**

[1] Nguyen Q, Estey E, Radd I, Rolston K, Kantarjian H, Jacobson K, et al. Cytomegalo‐ virus Pneumonia in Adults with Leukemia: An Emerging Problem. *CID* 2001; 32: 539-45.

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[15] Corona Nakamura AL, Monteón Ramos FJ*,* Troyo Sanroman R, Arias Merino MJ*,* Anaya Prado R. Incidence and predictive factors for cytomegalovirus infection in re‐

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**Chapter 4**

**Cytomegalovirus Infection in Liver Transplantation**

With the global evolution of organ transplantation in humans a new class of patients with special problems related to opportunistic infections after transplantation has appeared [1, 2 ].Some of these challenges infections with members of the herpesvirus family. Among these viruses, human cytomegalovirus (HCMV) often affects immunocompromised patients, HCMV can be reactivated by immunosuppression and cause significant morbidity and mortality [3,4]. In the postoperative period, HCMV infection can result in serious complica‐ tions in patients who received grafts by modulating the immune response [5]. However in immunocompetent individuals cytomegalovirus infection can be asymptomatic or cause symptoms similar to infectious mononucleosis syndrome, such as lymphadenopathy, fever,

This chapter presents the main clinical and epidemiological aspects related to cytomegalovirus

The discovery of HCMV began in 1881 when the histological effects of infection were observed in the kidney of a newborn child. In 1904, Ribbert identified the causative agent of "cytomegalic inclusion disease", whose name derives from the characteristic cytopathic effect, represented

and reproduction in any medium, provided the original work is properly cited.

© 2013 Sampaio et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

Ana Maria Sampaio, Ana Carolina Guardia,

Additional information is available at the end of the chapter

rash, malaise, arthralgia, hepatomegaly and splenomegaly [6].

infection and the importance of detection in liver transplant recipients.

Arlete Milan, Elaine Cristina Ataíde,

Sandra Botelho Cecilia Costa and Ilka de Fatima Santana Ferreira Boin

Rachel Silveira Bello Stucchi,

http://dx.doi.org/10.5772/56128

**2. Cytomegalovirus history**

**1. Introduction**

### **Cytomegalovirus Infection in Liver Transplantation**

Ana Maria Sampaio, Ana Carolina Guardia, Arlete Milan, Elaine Cristina Ataíde, Rachel Silveira Bello Stucchi, Sandra Botelho Cecilia Costa and Ilka de Fatima Santana Ferreira Boin

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/56128

#### **1. Introduction**

With the global evolution of organ transplantation in humans a new class of patients with special problems related to opportunistic infections after transplantation has appeared [1, 2 ].Some of these challenges infections with members of the herpesvirus family. Among these viruses, human cytomegalovirus (HCMV) often affects immunocompromised patients, HCMV can be reactivated by immunosuppression and cause significant morbidity and mortality [3,4]. In the postoperative period, HCMV infection can result in serious complica‐ tions in patients who received grafts by modulating the immune response [5]. However in immunocompetent individuals cytomegalovirus infection can be asymptomatic or cause symptoms similar to infectious mononucleosis syndrome, such as lymphadenopathy, fever, rash, malaise, arthralgia, hepatomegaly and splenomegaly [6].

This chapter presents the main clinical and epidemiological aspects related to cytomegalovirus infection and the importance of detection in liver transplant recipients.

#### **2. Cytomegalovirus history**

The discovery of HCMV began in 1881 when the histological effects of infection were observed in the kidney of a newborn child. In 1904, Ribbert identified the causative agent of "cytomegalic inclusion disease", whose name derives from the characteristic cytopathic effect, represented

by increases in cell volume and intracellular cytoplasmic inclusions in infected tissues [7]. In 1881 and 1921 similar cell characteristics were reported by Goodpasture and Talbot in a fatal case associated with this virus involving lung, liver and kidney from a newborn child [8].

endocytosis, entering pinocytic vesicles in which the envelope loss process is started, favored by a low pH. The rupture of the vesicles or fusion of the virus with the outer layer of the vesicle

Cytomegalovirus Infection in Liver Transplantation

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65

The intermediate phase lasts 24 hours, characterized by transcription and replication of viral DNA. The first step of viral gene expression is the synthesis of mRNA via host RNA poly‐ merase inside the core. The mRNA is translated by the host ribosomes into early and late viral proteins. The early proteins are enzymes required for viral genome replication [19]. The late

In the late phase, viral particles newly formed are grouped together within the capsid and begin the process of budding, during which the nucleocapsid adheres to specific sites of the membrane and interacts with the protein matrix. At this point, a process of evagination occurs

Infection is defined as seroconversion (an increase of 4 times or more in HCMV antibody titer in seronegative or seropositive patients), virus circulation in any body fluid such as urine, nasopharyngeal secretions or blood [7]. CMV infects only the human population and its transmission occurs both horizontally and vertically and may include oropharyngeal secre‐ tions, vaginal tears, seminal fluid, breast milk, urine, feces and blood [19]. In adulthood the CMV transmission may occur through heterosexual and homosexual contact, through blood and blood products and through organ transplantation, the latter being an important route of

About 80% of the population between late childhood and early adolescence is already infected with CMV [21, 22] and can harbor the virus in various body sites, especially in the salivary glands and different types of leukocytes. With age the increased prevalence of antibodies is common. This may not depend on the geographical area, but the socio-economic status may be important [10, 23- 28]. The seroprevalence of CMV in populations at high socioeconomic level varies from 40% to 60%, increases after infection of early childhood and approximately 10% to 20% of children have their first infection episode before puberty [10]. In lower socioe‐ conomic populations the seroprevalence level is higher, ranging from 80% to 100%. In Brazil,

The clinical course of CMV in immunocompetent individuals may be asymptomatic or may resemble "Mononucleosis Syndrome" presented by persistent fever, myalgia, pharyngitis,

seroprevalence of cytomegalovirus averages 90% in adult populations [28].

lymphadenopathy, sweating and hepatosplenomegaly [10,28-34].

membrane deposits the core of the virus in the cell cytoplasm [13].

proteins include a polymerase replicating the viral genome [13].

and an enveloped particle flows from the membrane surface [13].

**4. Transmission and epidemiology**

transmission [12,19, 20].

**5. Clinical manifestations**

The first experimental evidence of the likely etiologic agent of "cytomegalic inclusion disease" was proposed by Cole and Kuttner in 1926, when they demonstrated the transmission of the disease in guinea pigs and suggested that this agent possessed characteristics of viral infection and was species-specific. Wolbach and Farber (1932) demonstrated the first evidence that the salivary gland virus was commonly involved and showed typical cytomegalic cells were found in 12% of children. In 1954, using the salivary infection mouse model, Smith isolated the virus in tissue culture [9].

In 1970 study groups were organized to evaluate the impact of infection in immunocompro‐ mised people and through this to propose infection control strategies. In the 1980s the control measures of CMV began with antiviral agents and immunological interventions [10].

#### **3. Structure features and replication engine**

CMV has an ultrastructure similar to other herpesviruses with four structural elements: an electron-dense core, an icosahedral symmetry capsid, a tegument occupying space between the capsid and an envelope steeped in glycoproteins and membrane proteins [11].

CMV carries a double-stranded DNA containing approximately 240 kb linear bases [12] encoding 33 structural proteins and an indefinite number of non-structural proteins, some of which are antigenic. The genome can be divided into two segments, designated as long component (L) and short (S) defined by repetitive sequence terminals (RT). The CMV has a complex genome due to the acquisitions of host genes and the duplication of viral genes [13]. It is a very thermolabile virus and its average life at 37 ° C is only 45 minutes, totally inactivated at 56 º C for 30 minutes [14].

During natural infection, viral replication can occur in epithelial, endothelial and muscle mesenchymal cells, hepatocytes, granulocytes and macrophages [15, 16]. In vivo studies with cells from immunocompetent and immunosuppressed patients show that CMV can commonly be isolated from polymorphonuclear leukocytes [17], which may represent an important replication site [14,16]. Variants of CMV are found in mice, monkeys and guinea pigs, but these strains are species-specific and do not infect humans [14].

The CMV replication mechanism occurs in three distinct stages, similar to other herpesviruses. The early phase occurs when the virus adheres to the host cell membrane (with the envelope loss and penetration into the cell), in the intermediate phase the gene expression and genome replication occur, and in the late phase, there is the assembly and release of new viral particles [16-18].

The "early" phase begins when surface proteins of the virion adhere to specific protein receptors on the cell surface through non-covalent bonds. The viral particles penetrate by endocytosis, entering pinocytic vesicles in which the envelope loss process is started, favored by a low pH. The rupture of the vesicles or fusion of the virus with the outer layer of the vesicle membrane deposits the core of the virus in the cell cytoplasm [13].

The intermediate phase lasts 24 hours, characterized by transcription and replication of viral DNA. The first step of viral gene expression is the synthesis of mRNA via host RNA poly‐ merase inside the core. The mRNA is translated by the host ribosomes into early and late viral proteins. The early proteins are enzymes required for viral genome replication [19]. The late proteins include a polymerase replicating the viral genome [13].

In the late phase, viral particles newly formed are grouped together within the capsid and begin the process of budding, during which the nucleocapsid adheres to specific sites of the membrane and interacts with the protein matrix. At this point, a process of evagination occurs and an enveloped particle flows from the membrane surface [13].

#### **4. Transmission and epidemiology**

by increases in cell volume and intracellular cytoplasmic inclusions in infected tissues [7]. In 1881 and 1921 similar cell characteristics were reported by Goodpasture and Talbot in a fatal case associated with this virus involving lung, liver and kidney from a newborn child [8].

The first experimental evidence of the likely etiologic agent of "cytomegalic inclusion disease" was proposed by Cole and Kuttner in 1926, when they demonstrated the transmission of the disease in guinea pigs and suggested that this agent possessed characteristics of viral infection and was species-specific. Wolbach and Farber (1932) demonstrated the first evidence that the salivary gland virus was commonly involved and showed typical cytomegalic cells were found in 12% of children. In 1954, using the salivary infection mouse model, Smith isolated the virus

In 1970 study groups were organized to evaluate the impact of infection in immunocompro‐ mised people and through this to propose infection control strategies. In the 1980s the control

CMV has an ultrastructure similar to other herpesviruses with four structural elements: an electron-dense core, an icosahedral symmetry capsid, a tegument occupying space between

CMV carries a double-stranded DNA containing approximately 240 kb linear bases [12] encoding 33 structural proteins and an indefinite number of non-structural proteins, some of which are antigenic. The genome can be divided into two segments, designated as long component (L) and short (S) defined by repetitive sequence terminals (RT). The CMV has a complex genome due to the acquisitions of host genes and the duplication of viral genes [13]. It is a very thermolabile virus and its average life at 37 ° C is only 45 minutes, totally inactivated

During natural infection, viral replication can occur in epithelial, endothelial and muscle mesenchymal cells, hepatocytes, granulocytes and macrophages [15, 16]. In vivo studies with cells from immunocompetent and immunosuppressed patients show that CMV can commonly be isolated from polymorphonuclear leukocytes [17], which may represent an important replication site [14,16]. Variants of CMV are found in mice, monkeys and guinea pigs, but these

The CMV replication mechanism occurs in three distinct stages, similar to other herpesviruses. The early phase occurs when the virus adheres to the host cell membrane (with the envelope loss and penetration into the cell), in the intermediate phase the gene expression and genome replication occur, and in the late phase, there is the assembly and release of new viral particles

The "early" phase begins when surface proteins of the virion adhere to specific protein receptors on the cell surface through non-covalent bonds. The viral particles penetrate by

measures of CMV began with antiviral agents and immunological interventions [10].

the capsid and an envelope steeped in glycoproteins and membrane proteins [11].

**3. Structure features and replication engine**

strains are species-specific and do not infect humans [14].

in tissue culture [9].

64 Manifestations of Cytomegalovirus Infection

at 56 º C for 30 minutes [14].

[16-18].

Infection is defined as seroconversion (an increase of 4 times or more in HCMV antibody titer in seronegative or seropositive patients), virus circulation in any body fluid such as urine, nasopharyngeal secretions or blood [7]. CMV infects only the human population and its transmission occurs both horizontally and vertically and may include oropharyngeal secre‐ tions, vaginal tears, seminal fluid, breast milk, urine, feces and blood [19]. In adulthood the CMV transmission may occur through heterosexual and homosexual contact, through blood and blood products and through organ transplantation, the latter being an important route of transmission [12,19, 20].

About 80% of the population between late childhood and early adolescence is already infected with CMV [21, 22] and can harbor the virus in various body sites, especially in the salivary glands and different types of leukocytes. With age the increased prevalence of antibodies is common. This may not depend on the geographical area, but the socio-economic status may be important [10, 23- 28]. The seroprevalence of CMV in populations at high socioeconomic level varies from 40% to 60%, increases after infection of early childhood and approximately 10% to 20% of children have their first infection episode before puberty [10]. In lower socioe‐ conomic populations the seroprevalence level is higher, ranging from 80% to 100%. In Brazil, seroprevalence of cytomegalovirus averages 90% in adult populations [28].

#### **5. Clinical manifestations**

The clinical course of CMV in immunocompetent individuals may be asymptomatic or may resemble "Mononucleosis Syndrome" presented by persistent fever, myalgia, pharyngitis, lymphadenopathy, sweating and hepatosplenomegaly [10,28-34].

After primary infection, CMV persists in host tissues and may be reactivated to cause disease – usually in children with congenital infection, organ transplant recipients, cancer patients undergoing chemotherapy and patients with HIV disease [7,10,29,35].

**6. Diagnosis**

practice.

**Molecular methods**

**viral antigens** and molecular methods [49, 48]…

The diagnosis of CMV infection can be done by serology, polymerase chain reaction (PCR), culture and viral antigenemia research. Early diagnosis is important as early treatment of asymptomatic active infection reduces morbidity [24, 31, 46, 47]. The first method of diagnosis used to identify the CMV was exfoliative cytology. This technique revealed the presence of large cells which had inclusions within the core, identified as cytomegalic inclusion. Later methods are more sensitive and specific. These are grouped into seven categories: cytological, histological, virus isolation, serological identification,, **Immunofluorescence, detection of**

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67

**Cytopathological techniques:** These methods can be performed on tissue and secretions aspirated material [7,8], but have low sensitivity so they currently have little use in clinical

**Histological Techniques:** A method of detecting inclusions by visualization of typical tissue. The finding of cells with typical inclusions allows often to correlate CMV lesion or dysfunction of the organ studied. Although this method has low sensitivity, it reveals invasive tissue disease [7]. The advantages are low cost, simplicity of use and availability of equipment.

**Viral Isolation:** CMV can be isolated from various biological materials, such as biological fluids (urine, saliva, blood, cervical secretions, breast milk, tears, semen, feces and washed

**Serological methods:** The modern serological methods detect the presence of IgM and IgG [51] usually by ELISA. This technique does not detect the virus in early stages of infection, as

**Immunofluorescence (IF):** A method that allows an early detection of the virus is immuno‐

**Detection of Viral Antigens (antigenemia):** Antigenemia offers high sensitivity and specific‐ ity. It is fast, direct and sensitive, and is considered a quantitative technique for viral load [54, 55]. CMV antigenemia is one of the earlier tests with positive results [17, 25, 51- 58] and becomes positive on average 9-18 days before establishment of the disease. It has been widely used for

The additional advantage of this method is that results can be expressed quantitatively, allowing observation of the clinical response to treatment [17, 59]. The disadvantage of this technique is the speed needed to process the collected material without loss of sensitivity - 6 to 8 hours [17]. In patients with neutropenia, this test cannot be performed due to low

**Polymerase chain reaction-PCR:** The qualitative PCR is often the first test to detect asympto‐ matic subclinical infection, but specific predictive value is low for the diagnosis of HCMV

the early detection of active infection in organ transplant recipients [17, 24, 25, 36, 56].

aspirates organs) and tissue obtained from biopsies or autopsies [49, 50].

antibodies are produced by the host only after this phase.

fluorescence usually using commercially available antibodies.

granulocyte count. On this situation, molecular assays are used.

Among the complications caused by CMV in transplanted patients increased long-term mortality and worsening graft survival are common [35-37]. Clinical disease caused by CMV is expressed by fever, malaise, myalgia, leukopenia (WBC less than 4.0000/mm3 ), in‐ creased transaminases (hepatitis), pulmonary (pneumonitis) and/or gastrointestinal (colitis, gastritis, esophagitis) and fever being the most common manifestation, which can also occur with neurological symptomatology compatible with encephalitis but these are rarer [29,38,39].

Clinical disease may reflect


The source of infection for both primary infection and superinfection is may include graft and blood transfusions. Immunosuppression may cause reactivation of CMV [40]. About two thirds of patients with primary infection are symptomatic, less than 20% in viral reactivation have symptoms and about 40% of reinfected individuals have symptoms attributable to CMV [10]. When primary infection occurs after transplantation the clinical impact is significant [41]. This is most common following allocation of grafts from donors with positive serology to seronegative recipients [42]. Immunosuppressive drugs such as azathioprine and cyclosporine have been implicated in the facilitation of CMV disease [7].

Diagnostic criteria include clinical signs known to be caused by this virus [43,44]. In liver transplant patients with active CMV infection, about 80% will develop clinical manifesta‐ tions of the disease and the rate may be higher when the recipient is seronegative and a donor is seropositive [44]. CMV infection is an independent risk factor for the develop‐ ment with opportunistic infections, as well as graft rejection [7]. The evidence of viral replication and clinical symptoms in transplant occurs mainly during the 1st to 4th month post-transplant.

The most common clinical manifestations are interstitial pneumonia, esophagitis, gastritis, colitis, retinitis, fever and delayed engraftment in bone marrow transplants [29,45]. During liver transplantation, primary infection tends to be more important as the CMV viremia may be limited to when virus replication is detected in peripheral blood or significant increase of specific antibodies without symptoms or viral syndrome presenting fever equal or greater than 38ºC, malaise, leukopenia, atypical lymphocytosis equal or less than 3-5% and thrombocyto‐ penia [14, 37, 42, 45,46].

Antiviral treatment controls the acute manifestation of the disease in most cases, but may not eradicate the CMV with recurrence reported in 26-31% of solid organ transplant recipients.. [14, 36].

#### **6. Diagnosis**

), in‐

After primary infection, CMV persists in host tissues and may be reactivated to cause disease – usually in children with congenital infection, organ transplant recipients, cancer patients

Among the complications caused by CMV in transplanted patients increased long-term mortality and worsening graft survival are common [35-37]. Clinical disease caused by CMV is expressed by fever, malaise, myalgia, leukopenia (WBC less than 4.0000/mm3

creased transaminases (hepatitis), pulmonary (pneumonitis) and/or gastrointestinal (colitis, gastritis, esophagitis) and fever being the most common manifestation, which can also occur with neurological symptomatology compatible with encephalitis but these are rarer

**2.** Secondary infection occurs when the reactivation of latent infection or superinfection;

The source of infection for both primary infection and superinfection is may include graft and blood transfusions. Immunosuppression may cause reactivation of CMV [40]. About two thirds of patients with primary infection are symptomatic, less than 20% in viral reactivation have symptoms and about 40% of reinfected individuals have symptoms attributable to CMV [10]. When primary infection occurs after transplantation the clinical impact is significant [41]. This is most common following allocation of grafts from donors with positive serology to seronegative recipients [42]. Immunosuppressive drugs such as azathioprine and cyclosporine

Diagnostic criteria include clinical signs known to be caused by this virus [43,44]. In liver transplant patients with active CMV infection, about 80% will develop clinical manifesta‐ tions of the disease and the rate may be higher when the recipient is seronegative and a donor is seropositive [44]. CMV infection is an independent risk factor for the develop‐ ment with opportunistic infections, as well as graft rejection [7]. The evidence of viral replication and clinical symptoms in transplant occurs mainly during the 1st to 4th month

The most common clinical manifestations are interstitial pneumonia, esophagitis, gastritis, colitis, retinitis, fever and delayed engraftment in bone marrow transplants [29,45]. During liver transplantation, primary infection tends to be more important as the CMV viremia may be limited to when virus replication is detected in peripheral blood or significant increase of specific antibodies without symptoms or viral syndrome presenting fever equal or greater than 38ºC, malaise, leukopenia, atypical lymphocytosis equal or less than 3-5% and thrombocyto‐

Antiviral treatment controls the acute manifestation of the disease in most cases, but may not eradicate the CMV with recurrence reported in 26-31% of solid organ transplant recipients..

undergoing chemotherapy and patients with HIV disease [7,10,29,35].

**1.** Primary infection, when it occurs in patients previously seronegative;

**3.** Tertiary infection by reinfection by other strains of the virus [7].

have been implicated in the facilitation of CMV disease [7].

[29,38,39].

post-transplant.

penia [14, 37, 42, 45,46].

[14, 36].

Clinical disease may reflect

66 Manifestations of Cytomegalovirus Infection

The diagnosis of CMV infection can be done by serology, polymerase chain reaction (PCR), culture and viral antigenemia research. Early diagnosis is important as early treatment of asymptomatic active infection reduces morbidity [24, 31, 46, 47]. The first method of diagnosis used to identify the CMV was exfoliative cytology. This technique revealed the presence of large cells which had inclusions within the core, identified as cytomegalic inclusion. Later methods are more sensitive and specific. These are grouped into seven categories: cytological, histological, virus isolation, serological identification,, **Immunofluorescence, detection of viral antigens** and molecular methods [49, 48]…

**Cytopathological techniques:** These methods can be performed on tissue and secretions aspirated material [7,8], but have low sensitivity so they currently have little use in clinical practice.

**Histological Techniques:** A method of detecting inclusions by visualization of typical tissue. The finding of cells with typical inclusions allows often to correlate CMV lesion or dysfunction of the organ studied. Although this method has low sensitivity, it reveals invasive tissue disease [7]. The advantages are low cost, simplicity of use and availability of equipment.

**Viral Isolation:** CMV can be isolated from various biological materials, such as biological fluids (urine, saliva, blood, cervical secretions, breast milk, tears, semen, feces and washed aspirates organs) and tissue obtained from biopsies or autopsies [49, 50].

**Serological methods:** The modern serological methods detect the presence of IgM and IgG [51] usually by ELISA. This technique does not detect the virus in early stages of infection, as antibodies are produced by the host only after this phase.

**Immunofluorescence (IF):** A method that allows an early detection of the virus is immuno‐ fluorescence usually using commercially available antibodies.

**Detection of Viral Antigens (antigenemia):** Antigenemia offers high sensitivity and specific‐ ity. It is fast, direct and sensitive, and is considered a quantitative technique for viral load [54, 55]. CMV antigenemia is one of the earlier tests with positive results [17, 25, 51- 58] and becomes positive on average 9-18 days before establishment of the disease. It has been widely used for the early detection of active infection in organ transplant recipients [17, 24, 25, 36, 56].

The additional advantage of this method is that results can be expressed quantitatively, allowing observation of the clinical response to treatment [17, 59]. The disadvantage of this technique is the speed needed to process the collected material without loss of sensitivity - 6 to 8 hours [17]. In patients with neutropenia, this test cannot be performed due to low granulocyte count. On this situation, molecular assays are used.

#### **Molecular methods**

**Polymerase chain reaction-PCR:** The qualitative PCR is often the first test to detect asympto‐ matic subclinical infection, but specific predictive value is low for the diagnosis of HCMV disease. It is not suitable for routine monitoring of patients on treatment [57]…why not???. It is a quick (4-6 hours), specific and extremely sensitive test but false positives may result from contamination during the test run. False negative results can also occur due to presence of inhibitors in the sample [55,60]. The sample type and method of extracting DNA from these samples must be carefully chosen to avoid this [31,61].

**8. Transplantation**

by CMV (see Section **xy**).

therapy and have capacity to detect drug resistance.

only for herpes simplex type 1 with Acyclovir.

found in our groups are similar to other services [24,25,30-32].

CMV is around 29 days following transplantation (range: 0-99 days) [30]..

infections by other viruses of the same family (HHV-6, HHV-7) [24,32].

making therapeutic strategies to minimize risks caused by this betaherpesvirus.

CMV seroprevalence is high in developing countries such as Brazil, so most of the patients and/or donors is CMV IgG positive. The techniques chosen for the laboratorial monitoring in our service after liver transplantation are antigenemia and Nested-PCR (N-PCR). These techniques detect the active viral replication and minimize the damage of the disease caused

Cytomegalovirus Infection in Liver Transplantation

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69

We diagnose active infection from one positive result by antigenemia, or two positive N-PCR findings over an interval equal or smaller than 30 days. As antigenemia can detect CMV a few days to one week before the appearance of the symptoms, the Ganciclovir is initiated after the detection of a positive cell even without clinical symptoms if the patient presents IgG negative and the donor presents IgG positive. Patients are monitored while in hospital and after discharge following a protocol: weekly from the first to the second month, fortnightly in the third-fourth months and monthly until six months. After this period the antigenemia or N-PCR is performed only if there is a suggestive clinical diagnosis of CMV infection. The assessment of antigenemia also provides an estimate of viral load that is useful in the differ‐ entiation of CMV disease from other complications. Thus we evaluate the efficacy of antiviral

CMV is frequently detected in our patients after liver transplantation [24,25,30,31]. Detection of N-PCR and antigenemia are useful markers for active infection [30,31].The rates of CMV

We also observed that symptomatic CMV infection occurs during the first three months after transplantation. We consider that this high incidence of symptomatic CMV infection is due to the high prevalence of the virus in Brazilian population. The mean time for initial detection

In our service, CMV DNA diagnosed in pretransplantation graft biopsy specimens remained positive posttransplantation on graft biopsies. This common complication negatively influen‐ ces liver transplantation outcomes and is a risk factor to develop acute cellular rejection episodes [67].Ganciclovir prophylaxis for CMV is not performed at our institution unless the patient is preoperative negative IgG and the donor is CMV positive. Prophylaxis is performed

Another relevant issue at our service is opportunistic infections, which are often seen in patients at risk for CMV and have been recognized by our staff as a significant risk factor for graft failure and death [24]. Active CMV infection may increase the risk of bacterial, fungal, viral, and others, as well as post-transplant lymphoproliferative disease. [31] This includes co-

The clinical impact of CMV-infected patients observed by our team [24] shows that it is extremely important to follow up these patients. These data have helped the medical staff

**Nested PCR (Polymerase Chain Double):** Nested PCR (N-PCR) has been used to increase the sensitivity and specificity of simple PCR. Here the product of the first PCR, amplified with a primer pair, is subjected to a new amplification reaction using another pair of primers internal to the first, the product being then detected by agarose gel electrophoresis [62]. Nested PCR technique to diagnose CMV infection produces results consistent with classical culture, reaching 100% specificity and 93% sensitivity in a shorter time frame [63- 66].

**Real-time PCR:** Real Time PCR amplification (RT PCR) presents high sensitivity and precision. It has been used for the detection and monitoring of viral load. Its sensitivity and specificity are directly related to the choice of "primers" and probes, and the accuracy is determined by the threshold cycle, which is calculated during the exponential phase of the reaction. Formation of a fluorescently labeled product is monitored at each amplification cycle in a single instru‐ ment generating quantitative results. [58].

#### **7. Treatment**

Ganciclovir has been the "gold standard" for treatment of CMV disease although resistance to this drug has been reported and should be considered in unresponsive patients. Some studies have focused on genotyping of CMV that could indicate samples that were resistant to conventional treatment. Inadequate dosing may reduce clinical efficacy and promote resistance (44)

Antiviral administration is generally initiated in the immediate or early post-transplant period, and continues for 3 to 6 months. Various antiviral drugs have been used, including acyclovir, valaciclovir, intravenous ganciclovir, oral valganciclovir or intravenous (IV) ganciclovir, and valganciclovir. In preventive therapy, laboratory monitoring detects asymptomatic viral replication and antiviral therapy is initiated to prevent progression to clinical disease. For non severe CMV disease, oral valganciclovir (900 mg orally every 12 hr) or IV ganciclovir (5 mg/kg every 12hr) are recommended as first-line treatment. Renal function should be moni‐ tored frequently during treatment, with estimated or measured glomerular filtration rate. Optimal length of treatment should be achieved by monitoring weekly viral loads and treating until one or two consecutive negative samples are obtained, but not shorter than 2 weeks. Duration should reflect the likelihood of recurrent CMV infection. In cases of serious disease and in tissue-invasive disease without viremia, longer treatment periods with clinical moni‐ toring of the specific disease manifestation are recommended. In cases of recurrent CMV disease, prophylaxis after retreatment may need to be prolonged. [44].

#### **8. Transplantation**

disease. It is not suitable for routine monitoring of patients on treatment [57]…why not???. It is a quick (4-6 hours), specific and extremely sensitive test but false positives may result from contamination during the test run. False negative results can also occur due to presence of inhibitors in the sample [55,60]. The sample type and method of extracting DNA from these

**Nested PCR (Polymerase Chain Double):** Nested PCR (N-PCR) has been used to increase the sensitivity and specificity of simple PCR. Here the product of the first PCR, amplified with a primer pair, is subjected to a new amplification reaction using another pair of primers internal to the first, the product being then detected by agarose gel electrophoresis [62]. Nested PCR technique to diagnose CMV infection produces results consistent with classical culture,

**Real-time PCR:** Real Time PCR amplification (RT PCR) presents high sensitivity and precision. It has been used for the detection and monitoring of viral load. Its sensitivity and specificity are directly related to the choice of "primers" and probes, and the accuracy is determined by the threshold cycle, which is calculated during the exponential phase of the reaction. Formation of a fluorescently labeled product is monitored at each amplification cycle in a single instru‐

Ganciclovir has been the "gold standard" for treatment of CMV disease although resistance to this drug has been reported and should be considered in unresponsive patients. Some studies have focused on genotyping of CMV that could indicate samples that were resistant to conventional treatment. Inadequate dosing may reduce clinical efficacy and promote

Antiviral administration is generally initiated in the immediate or early post-transplant period, and continues for 3 to 6 months. Various antiviral drugs have been used, including acyclovir, valaciclovir, intravenous ganciclovir, oral valganciclovir or intravenous (IV) ganciclovir, and valganciclovir. In preventive therapy, laboratory monitoring detects asymptomatic viral replication and antiviral therapy is initiated to prevent progression to clinical disease. For non severe CMV disease, oral valganciclovir (900 mg orally every 12 hr) or IV ganciclovir (5 mg/kg every 12hr) are recommended as first-line treatment. Renal function should be moni‐ tored frequently during treatment, with estimated or measured glomerular filtration rate. Optimal length of treatment should be achieved by monitoring weekly viral loads and treating until one or two consecutive negative samples are obtained, but not shorter than 2 weeks. Duration should reflect the likelihood of recurrent CMV infection. In cases of serious disease and in tissue-invasive disease without viremia, longer treatment periods with clinical moni‐ toring of the specific disease manifestation are recommended. In cases of recurrent CMV

disease, prophylaxis after retreatment may need to be prolonged. [44].

reaching 100% specificity and 93% sensitivity in a shorter time frame [63- 66].

samples must be carefully chosen to avoid this [31,61].

68 Manifestations of Cytomegalovirus Infection

ment generating quantitative results. [58].

**7. Treatment**

resistance (44)

CMV seroprevalence is high in developing countries such as Brazil, so most of the patients and/or donors is CMV IgG positive. The techniques chosen for the laboratorial monitoring in our service after liver transplantation are antigenemia and Nested-PCR (N-PCR). These techniques detect the active viral replication and minimize the damage of the disease caused by CMV (see Section **xy**).

We diagnose active infection from one positive result by antigenemia, or two positive N-PCR findings over an interval equal or smaller than 30 days. As antigenemia can detect CMV a few days to one week before the appearance of the symptoms, the Ganciclovir is initiated after the detection of a positive cell even without clinical symptoms if the patient presents IgG negative and the donor presents IgG positive. Patients are monitored while in hospital and after discharge following a protocol: weekly from the first to the second month, fortnightly in the third-fourth months and monthly until six months. After this period the antigenemia or N-PCR is performed only if there is a suggestive clinical diagnosis of CMV infection. The assessment of antigenemia also provides an estimate of viral load that is useful in the differ‐ entiation of CMV disease from other complications. Thus we evaluate the efficacy of antiviral therapy and have capacity to detect drug resistance.

CMV is frequently detected in our patients after liver transplantation [24,25,30,31]. Detection of N-PCR and antigenemia are useful markers for active infection [30,31].The rates of CMV found in our groups are similar to other services [24,25,30-32].

We also observed that symptomatic CMV infection occurs during the first three months after transplantation. We consider that this high incidence of symptomatic CMV infection is due to the high prevalence of the virus in Brazilian population. The mean time for initial detection CMV is around 29 days following transplantation (range: 0-99 days) [30]..

In our service, CMV DNA diagnosed in pretransplantation graft biopsy specimens remained positive posttransplantation on graft biopsies. This common complication negatively influen‐ ces liver transplantation outcomes and is a risk factor to develop acute cellular rejection episodes [67].Ganciclovir prophylaxis for CMV is not performed at our institution unless the patient is preoperative negative IgG and the donor is CMV positive. Prophylaxis is performed only for herpes simplex type 1 with Acyclovir.

Another relevant issue at our service is opportunistic infections, which are often seen in patients at risk for CMV and have been recognized by our staff as a significant risk factor for graft failure and death [24]. Active CMV infection may increase the risk of bacterial, fungal, viral, and others, as well as post-transplant lymphoproliferative disease. [31] This includes coinfections by other viruses of the same family (HHV-6, HHV-7) [24,32].

The clinical impact of CMV-infected patients observed by our team [24] shows that it is extremely important to follow up these patients. These data have helped the medical staff making therapeutic strategies to minimize risks caused by this betaherpesvirus.

**Acknowledgements**

Nível Superior (CAPES).

**Author details**

Ana Maria Sampaio1

nas, Brazil

**References**

206-282.

70-213.

Rachel Silveira Bello Stucchi2

Ilka de Fatima Santana Ferreira Boin1\*

Biologist Eliana Duarte Quizini Bueno

This study received financial support from Coordenação de Aperfeiçoamento de Pessoal de

, Sandra Botelho Cecilia Costa2

1 Department of Surgery - Liver Transplant Unit of the State University of Campinas, Brazil

2 Department of Clinical Medicine - Liver Transplantation Unit, State University of Campi‐

[1] Levinson, W, & Jawetz, E. Medical microbiology & immunology: examination and board review 6th ed. New York: Lange Medical Books/McGraw-Hill (2000). Part. IV.,

[2] Tong CYWBakran A, Willians H, Cheung CY, Peiris JSM. Association of human her‐ pes virus 7 with CMV disease in renal transplant recipients. Transplantation (2000). ,

[3] Guo, Z, Chen, H. R, Liu, X. D, Bian, J. M, He, X. F, Lou, J. X, et al. Clinical analysis of cytomegalovirus infection after allogeneic hematopoietic stem cell transplantation

[4] Lautenschlager, I, Halme, L, Hockerstedt, K, Krogerus, L, & Taskinen, E. Cytomega‐ lovirus infection of the Liver Transplant: Virological, Histological, Immunological,

[5] Weigand, K, Schnitzler, P, Schimidt, J, Chahoud, F, Gotthardt, D, Schemmer, P, et al. Cytomegalovirus Infection After Liver Transplantation Incidence, Risks, And Bene‐

Zhong Shi Yan Xue Ye Xue Za Zhi (2012). , 20(4), 971-4.

and Clinical Observations. Transpl Infect Dis (2006). , 8-21.

fits of Prophylaxis. Transplant Proc (2010). , 42-2634.

, Arlete Milan2

, Elaine Cristina Ataíde1

Cytomegalovirus Infection in Liver Transplantation

http://dx.doi.org/10.5772/56128

71

and

,

, Ana Carolina Guardia1

\*Address all correspondence to: ilkaboin@yahoo.com

**Figure 1.** Nuclei of neutrophils stained in brown indicating positive pp65-atigenemia (counterstained with Harris's hematoxylin). Mouse C10 and C11 monoclonal antibodies against pp65-matrix CMV antigen and rabbit anti-mouse Ig horseradish peroxidase conjugate. The reaction was revealed by hydrogen peroxide and amino-ethyl-carbazole24


**Table 1.** Complete list of human herpesvirus

#### **9. Conclusion**

Few patients remain free of betaherpesvirus after liver transplantation. Active CMV infection is common especially in the first weeks after grafting. We believe it is important to continue monitoring CMV infection after transplantation, especially when the prevalence in the general population is high.

#### **Acknowledgements**

Biologist Eliana Duarte Quizini Bueno

This study received financial support from Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).

#### **Author details**

Ana Maria Sampaio1 , Ana Carolina Guardia1 , Arlete Milan2 , Elaine Cristina Ataíde1 , Rachel Silveira Bello Stucchi2 , Sandra Botelho Cecilia Costa2 and Ilka de Fatima Santana Ferreira Boin1\*

\*Address all correspondence to: ilkaboin@yahoo.com

1 Department of Surgery - Liver Transplant Unit of the State University of Campinas, Brazil

2 Department of Clinical Medicine - Liver Transplantation Unit, State University of Campi‐ nas, Brazil

#### **References**

**Figure 1.** Nuclei of neutrophils stained in brown indicating positive pp65-atigenemia (counterstained with Harris's hematoxylin). Mouse C10 and C11 monoclonal antibodies against pp65-matrix CMV antigen and rabbit anti-mouse Ig horseradish peroxidase conjugate. The reaction was revealed by hydrogen peroxide and amino-ethyl-carbazole24

**Virus Synonym Subfamily Abbreviation**

Human Herpesvirus-1 Herpes simplex-1 || HSV-1/HHV-1 Human Herpesvirus -2 Herpes simplex-2 || HSV-2/HHV-2 Human Herpesvirus -3 Varicella-zoster || VZV/HHV-3 Human Herpesvirus -4 Epstein-Barr || EBV/HSV-4 Human Herpesvirus -5 Cytomegalovirus || HCMV/CMV/HHV-5 Human Herpesvirus -6 None || HHV-6 Human Herpesvirus -7 None || HHV-7 Human Herpesvirus -8 None || KSHV/HHV-8

Few patients remain free of betaherpesvirus after liver transplantation. Active CMV infection is common especially in the first weeks after grafting. We believe it is important to continue monitoring CMV infection after transplantation, especially when the prevalence in the general

**Table 1.** Complete list of human herpesvirus

70 Manifestations of Cytomegalovirus Infection

**9. Conclusion**

population is high.


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[33] Sebeková, K, Feber, J, Carpenter, B, Shaw, L, Karnauchow, T, Diaz-mitoma, F, et al. Tissue viral dna is associated with chronic allograft nephropathy (2005). , 95, 598-603.

[34] Pannuti, C. S. Citomegalia. In: Ferreira, A. W.; Ávila, S.L.M. eds. Diagnóstico Labora‐ torial das principais Doenças Infecciosas e Autoimunes, 2ª. Edição, Editora Guana‐

[35] Linhares, L, Sanclemente, G, Cervera, C, Hoyo, I, Cofán, F, Ricart, M. J, et al. Influ‐ ence of cytomegalovirus disease in outcome of solid organ transplant patients. Trans‐

[36] Sampathkumar, P, & Paya, C. V. Management of cytomegalovirus infection after liv‐

[37] Angelis, M, Cooper, J, & Freeman, R. B. Impact of donor infections on outcome of or‐

[38] Ljungman, P, Griffiths, P, & Paya, C. Definition of cytomegalovirus infection and dis‐

[39] Humar, A, Kumar, D, Gray, M, Moussa, G, Venkataraman, S, Kumar, R, & Tipples, G. A. A Prospective assessment of cytomegalovirus immune evasion gene transcrip‐ tion profiles in transplant patients with cytomegalovirus infection. Transplantation

[40] Van Der MeerJtm Drew.; Bowden RA.; Galasso Gl.; Griffiths PD.; Jabs DA; et al. Summary of the international consensus symposium on advances in the diagnosis, treatment and prophylaxis of cytomegalovirus infection. Antiviral Res (1996). , 32,

[41] Singh, N, Wannstedt, C, Keyes, L, Wagener, M. M, Vera, M, Cacciarelli, T. V, et al. Impact of evolving trends in recipient and donor characteristics on cytomegalovirus

[42] Freeman, R. B. Risk factors for cytomegalovirus viremia and disease developing after prophylaxis in high-risk solid-organ transplant recipients. Transplantation (2004). ,

[43] Mustafa, M. M. Cytomegalovirus infection and disease in the immunocompromised

[44] Kotton, C. N, Humar, A, Caliendo, A. M, Emery, V, Lautenschlager, I, Lazzarotto, T, et al. Transplantation Society International CMV Consensus Group. International consensus guidelines on the management of cytomegalovirus in solid organ trans‐

infection in liver transplant recipients. Transplantation (2004). , 77, 106-10.

124-9.

74 Manifestations of Cytomegalovirus Infection

bara Koogan (2001). , 5-68.

(2007). , 83(9), 1200-6.

119-140.

78, 1765-1773.

plant Proc (2011). , 43, 2145-2148.

er transplantation. Liver Transpl (2000). , 6(2), 144-156.

thotopic liver transplantation (2003). , 451-462.

host. The Ped Inf Dis J (1994). , 13, 249-259.

plantation. Transplantation (2010). , 89, 779-95.

ease in transplant recipients. Clin Infect Dis (2002).


[59] Lianghui, G, Shusen, Z, Tinoba, L, Yan, S, Welling, W, & Anwei, L. Deferred versus prophylactic therapy with ganciclovir for cytomegalovirus in allograft liver trans‐ plantation. Transplant Proc (2004). , 36, 1502-1505.

**Chapter 5**

**The Footprint of CMV Infection May Last a Lifetime**

Cytomegalovirus (CMV) is a β-herpesvirus able to replicate in fibroblasts, endothelial cells and monocytes [1]. CMV infection is usually asymptomatic, but causes a mononucleosis-like illness in some individuals. CMV disease can manifest as a syndrome or as an acute infection of an organ or tissue. CMV syndrome is characterized by fever, leukopenia, hepato-spleno‐ megaly, myalgias and occasionally pneumonitis. Sites of acute CMV infection include brain, heart, kidneys, liver and eyes. CMV colitis and CMV enteritis are manifestations of CMV disease in solid organ transplant recipients, bone marrow transplant recipients and HIV patients [2]. CMV retinitis was a common AIDS-defining illness before antiretroviral therapy (ART) became available, and remains a significant cause of blindness in HIV patients in the

In considering the role of CMV in human health, many studies have overlooked the fact that 50-90% of all populations are seropositive. As the virus has the capacity of latency and is known to be reactivated by "stress" (immunosuppression), it is likely that most people harbour latent virus [2]. Much of literature related to CMV is derived from studies of laboratory mice infected with a related virus Murine Cytomegalovirus (MCMV), which shares a similar genomic organisation and some sequence homology with human CMV. It is promoted as a useful model to study host-interaction because it shares similar in-vivo properties to human CMV after infection. Differences in the susceptibility of inbred strains of laboratory mice to MCMV infection has allowed several mechanisms of virological control to be characterised [4, 5], but

**1.** CMV has over 200 reading frames with potential to encode proteins [1].Of the proteins characterised, many are redundant for viral replication *in vitro*. These include homologues of host genes "picked up" since mice and humans diverged during mammalian evolution. If we assume that such genes are retained because they confer a survival advantage, then

and reproduction in any medium, provided the original work is properly cited.

© 2013 Price; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

© 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

distribution, and reproduction in any medium, provided the original work is properly cited.

there are several areas where extrapolation to human CMV is problematic.

Additional information is available at the end of the chapter

Patricia Price

**1. Introduction**

developing world [3]

http://dx.doi.org/10.5772/54798


### **The Footprint of CMV Infection May Last a Lifetime**

#### Patricia Price

[59] Lianghui, G, Shusen, Z, Tinoba, L, Yan, S, Welling, W, & Anwei, L. Deferred versus prophylactic therapy with ganciclovir for cytomegalovirus in allograft liver trans‐

[60] Piiparinen, H, Höckerstedt, K, Grönhagen-riska, C, & Lautenschlager, I. Comparison of two quantitative CMV PCR tests, Cobas Amplicor CMV monitor and taqman as‐ say, and assay in the determination of viral loads from peripheral blood of organ

[61] Peigo, M. F, Thomasini, R. L, Puglia, A. L, Costa, S. C, Bonon, S. H, Boin, I. F, et al. Human herpesvirus-7 in brazilian liver transplant recipients. a follow-op comparison between molecular and immunological assays. Transplant Infect Dis (2009). , 11,

[62] Abecassis, M. M, Koffron, A. J, Buckingham, M, Kaufman, D. B, Fryer, J. P, Stuart, J, et al. Role of PCR in the diagnosis and management of cmv in solid organ recipients. what is the predictive value for development of disease and should pcr be used to

[63] Olive, D. M, et al. Mufti S, Simsek M, Fayez H, al Nakib W. Direct Detection of Hu‐ man Cytomegalovirus in Urine Specimens From Renal Transplant Patients Following

[64] Costa, F. A, Soki, M. N, & Andrade, P. D. Bonon SHA, Thomasini RL, Sampaio AM, et al. Simultaneous monitoring of CMV and human herpesvirus 6 infections and dis‐ eases in liver transplant patients: one-year follow-up. Clinics (2011). , 66, 949-53. [65] Evans, M. J, Edwards-spring, Y, Myers, J, Wendt, A, Povinelli, D, Amsterdam, D, et al. Polymerase chain reaction assays for the detection of cytomegalovirus in organ

[66] Gerna, G, Zavattoni, M, Percivalle, E, Zella, D, Torsellini, M, & Revello, M. G. Diag‐ nosis of human cytomegalovirus infections in the immunocompromised host. Clin

[67] Guardia-silva, A. C, Stucchi, R. S, Sampaio, A. M, Milan, A, Costa, S. C, & Boin, I. F. Detection of cytomegalovirus and human herpesvirus-6 DNA in liver biopsy speci‐ mens and their correlation with rejection after liver transplantation. Transplant Proc.

Polymerase Chain Reaction Amplification. J Med Virol (1989). , 29(4), 232-7.

and bone marrow transplant recipients. Immunol Invest (1997).

plantation. Transplant Proc (2004). , 36, 1502-1505.

transplant patients. J Clin Virol (2004). , 65.

guide antiviral therapy. Transplant Proc (1997).

497-502.

76 Manifestations of Cytomegalovirus Infection

Diagn Virol (1996).

(2012). , 44(8), 2441-4.

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/54798

#### **1. Introduction**

Cytomegalovirus (CMV) is a β-herpesvirus able to replicate in fibroblasts, endothelial cells and monocytes [1]. CMV infection is usually asymptomatic, but causes a mononucleosis-like illness in some individuals. CMV disease can manifest as a syndrome or as an acute infection of an organ or tissue. CMV syndrome is characterized by fever, leukopenia, hepato-spleno‐ megaly, myalgias and occasionally pneumonitis. Sites of acute CMV infection include brain, heart, kidneys, liver and eyes. CMV colitis and CMV enteritis are manifestations of CMV disease in solid organ transplant recipients, bone marrow transplant recipients and HIV patients [2]. CMV retinitis was a common AIDS-defining illness before antiretroviral therapy (ART) became available, and remains a significant cause of blindness in HIV patients in the developing world [3]

In considering the role of CMV in human health, many studies have overlooked the fact that 50-90% of all populations are seropositive. As the virus has the capacity of latency and is known to be reactivated by "stress" (immunosuppression), it is likely that most people harbour latent virus [2]. Much of literature related to CMV is derived from studies of laboratory mice infected with a related virus Murine Cytomegalovirus (MCMV), which shares a similar genomic organisation and some sequence homology with human CMV. It is promoted as a useful model to study host-interaction because it shares similar in-vivo properties to human CMV after infection. Differences in the susceptibility of inbred strains of laboratory mice to MCMV infection has allowed several mechanisms of virological control to be characterised [4, 5], but there are several areas where extrapolation to human CMV is problematic.

**1.** CMV has over 200 reading frames with potential to encode proteins [1].Of the proteins characterised, many are redundant for viral replication *in vitro*. These include homologues of host genes "picked up" since mice and humans diverged during mammalian evolution. If we assume that such genes are retained because they confer a survival advantage, then

© 2013 Price; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

T-

the pathogenic pathways initiated by the murine and human viruses must be subtly different. This has been demonstrated with CMV-encoded chemokines [6]. >may<\$%&?>cause<\$%&?>death<\$%&?>[4].This<\$%&?>is<\$%&?>not<\$%&?>seen<\$%&?>in<\$%&?>people,<\$%&?>but<\$%&?>has< \$%&?>been<\$%&?>used<\$%&?>in<\$%&?>many<\$%&?>studies<\$%&?>to<\$%&?>examine<\$%&?>immune<\$%&?>responses<\$%&?

ptible<\$%&?>strains<\$%&?>can<\$%&?>readily<\$%&?>be<\$%&?>infected<\$%&?>with<\$%&?>murine<\$%&?>CMV<\$%&?>at<\$%& ?>a<\$%&?>dose<\$%&?>that<\$%&?>destroys<\$%&?>their<\$%&?>spleen<\$%&?>and<\$%&?>other<\$%&?>organs,<\$%&?>and<\$%&?

**2. Immune control of CMV**

senescent phenotype (CD45R0+

studies suggest that a rapid CD4+

nance of latency have not been identified.

eventually controlled by T-cells. CD4+

salivary gland [17]. CD8+

impetus to avoid CD8+

CMV disease.

T-cell and antibody responses may reflect CMV replication rather than protect against it. CD8+ T-cell responses to CMV can be assessed by IFNγ ELISpot or using tetramers or pentamers that mark cells reacting with a particular CMV peptide presented by a particular HLA molecule (usually HLA-A2). Gamadia *et al* [12]reported that frequencies of CMV-specific CD8+

were significantly higher in immunosuppressed transplant recipients than in healthy donors, suggesting that these responses may reflect exposure rather than protection. This is consistent with evidence that CMV encodes proteins that down regulate T-cell recognition of infected cells, and thus evade immune detection. This includes the degradation of HLA class I and II molecules by unique short (US) proteins and disruption of antigen processing by an infected antigen-presenting cell [13].CMV-specific cells predominantly have an effector-memory or

primary CMV infection in renal transplant recipients [14], but the cells critical for the mainte‐

Extensive studies of MCMV infection in laboratory mice have mapped protective NK cellmediated responses to the Ly49 gene cluster [equivalent to human Killer Cell Immunoglobu‐ lin-like receptor (KIR) genes]. Mouse strains have distinct Ly49 gene repertoires, which correlate with resistance to MCMV [15]. The activating receptor Ly49H is implicated in protection, and several members of the Ly49 family interact with MCMV encoded proteins [16]. In mice without a protective NK response (eg: through Ly49H), MCMV infections are

in control of reactivated MCMV, where frequent boosting expands specific CD8+ T-cell clones. MCMV encodes genes able to regulate MHC class I expression, demonstrating an evolutionary

CD8+ T-cell responses have been identified, but it is a limitation that all studies use laboratory strains of MCMV rather than primary isolates [18]. This highlights the need to study human

Direct evidence that NK cells can control CMV in humans is available from a study of a congenitally T-cell deficient child with acute CMV infection and a 10-fold expansion of NK cells with restricted receptor diversity. Acute illness resolved and NK cells returned to normal levels with clearance of plasma CMV DNA [19].This fits teleological and genetic evidence that NK cells control CMV. Human and mouse CMV diverged with their host species and have independently evolved proteins able to subvert protective NK responses [20]. This includes homologues of HLA-G (UL18) and HLA-E signal peptide (UL40), which interact with NK inhibitory receptors (LIR-1 and NKG2C, resp.) (Reviewed in[21] ) In support of a role for NK cells in CMV and HIV disease, we showed that heterozygous carriage of allele 2 at LIR-1

A role for NK cells in the control of CMV is also consistent with evidence that carriage of more genes for activating KIR receptors protects against CMV reactivation in immunosuppressed

(rs1061680; LILRB1 I142T) associated with CMV disease and nadir CD4+

or CD45RA+

CD27<sup>−</sup>

T-cell response was also essential to avoid symptomatic

T-cells are needed to control MCMV persistence in the

T-cells recognising immediate early (IE) epitopes are also implicated

T-cell responses. Critical epitopes and *H-2* loci initiating protective

CCR7<sup>−</sup>

The Footprint of CMV Infection May Last a Lifetime

http://dx.doi.org/10.5772/54798

CD27<sup>−</sup>

CCR7<sup>−</sup>

T-cells

79

, resp.). Subsequent

T-cell counts [22].


To avoid translational issues between studies of MCMV in mice and HCMV in humans, we need to look more closely at people infected with CMV. This must include primary disease and the effects of long term asymptomatic CMV infection in immune competent hosts. A lesson that we can take from MCMV is the effects on multiple cells and organs, including the adrenals, pancreas and salivary glands [4, 5, 10, 11]. Sensitive PCR-based viral load assays are now available, but these are only routinely applied to blood, urine or saliva of patients at risk of acute disease. There is little probability of detecting latent CMV. Here we present a tool to evaluate the lifetime effects of CMV on human health - the footprint of CMV. We also sum‐ marise evidence that natural killer (NK) cells may regulate the footprint of CMV. The likely impact in HIV patients is presented as Figure 1. \$%&?>and<\$%&?>organs,<\$%&?>including<\$%&?>the<\$%&?>adrenals,<\$%&?>pancreas<\$%&?>and<\$%&?>salivary<\$%&?>gland s<\$%&?>[4,<\$%&?>5, 10, 11].<\$%&?>Sensitive<\$%&?>PCRbased<\$%&?>viral<\$%&?>load<\$%&?>assays<\$%&?>are<\$%&?>now<\$%&?>available,<\$%&?>but<\$%&?>these<\$%&?>are<\$%&?> only<\$%&?>routinely<\$%&?>applied<\$%&?>to<\$%&?>blood,<\$%&?>urine<\$%&?>or<\$%&?>saliva<\$%&?>of<\$%&?>patients<\$%& ?>at<\$%&?>risk<\$%&?>of<\$%&?>acute<\$%&?>disease.<\$%&?>There<\$%&?>is<\$%&?>little<\$%&?>probability<\$%&?>of<\$%&?>de tecting<\$%&?>latent<\$%&?>CMV.<\$%&?>Here<\$%&?>we<\$%&?>present<\$%&?>a<\$%&?>tool<\$%&?>to<\$%&?>evaluate<\$%&?>o f<\$%&?>the<\$%&?>lifetime<\$%&?>effects<\$%&?>of<\$%&?>CMV<\$%&?>on<\$%&?>human<\$%&?>health<\$%&?>- <\$%&?>the<\$%&?>footprint<\$%&?>of<\$%&?>CMV.<\$%&?>We<\$%&?>also<\$%&?>summarise<\$%&?>evidence<\$%&?>that<\$%&? >natural<\$%&?>killer<\$%&?>(NK)<\$%&?>cells<\$%&?>may<\$%&?>regulate<\$%&?>the<\$%&?>footprint<\$%&?>of<\$%&?>CMV.<\$ %&?>The<\$%&?>likely<\$%&?>impact<\$%&?>in<\$%&?>HIV<\$%&?>patients<\$%&?>is<\$%&?>presented<\$%&?>as<\$%&?>Figure<\$ %&?>1.

Figure 1. HIV<\$%&?>disease<\$%&?>has<\$%&?>several<\$%&?>avenues<\$%&?>to<\$%&?>enhance<\$%&?>the<\$%&?>footprint<\$%&?>of<\$%&?>C **Figure 1.** HIV disease has several avenues to enhance the footprint of CMV and thereby promote cardiovascular disease.

than<\$%&?>protect<\$%&?>against<\$%&?>it.<\$%&?>CD8+<\$%&?>T-

molecule<\$%&?>(usually<\$%&?>HLA-

specific<\$%&?>CD8+<\$%&?>T-

MV<\$%&?>and<\$%&?>thereby<\$%&?>promote<\$%&?>cardiovascular<\$%&?>disease.

**2.<\$%&?>Immune<\$%&?>control<\$%&?>of<\$%&?>CMV** 

cell<\$%&?>and<\$%&?>antibody<\$%&?>responses<\$%&?>may<\$%&?>reflect<\$%&?>CMV<\$%&?>replication<\$%&?>rather<\$%&?>

cell<\$%&?>responses<\$%&?>to<\$%&?>CMV<\$%&?>can<\$%&?>be<\$%&?>assessed<\$%&?>by<\$%&?>IFNγ<\$%&?>ELISpot<\$%&?> or<\$%&?>using<\$%&?>tetramers<\$%&?>or<\$%&?>pentamers<\$%&?>that<\$%&?>mark<\$%&?>cells<\$%&?>reacting<\$%&?>with<\$ %&?>a<\$%&?>particular<\$%&?>CMV<\$%&?>peptide<\$%&?>presented<\$%&?>by<\$%&?>a<\$%&?>particular<\$%&?>HLA<\$%&?>

cells<\$%&?>were<\$%&?>significantly<\$%&?>higher<\$%&?>in<\$%&?>immunosuppressed<\$%&?>transplant<\$%&?>recipients<\$%

A2).<\$%&?>Gamadia*<\$%&?>et<\$%&?>al*<\$%&?>[12]reported<\$%&?>that<\$%&?>frequencies<\$%&?>of<\$%&?>CMV-

#### >may<\$%&?>cause<\$%&?>death<\$%&?>[4].This<\$%&?>is<\$%&?>not<\$%&?>seen<\$%&?>in<\$%&?>people,<\$%&?>but<\$%&?>has< **2. Immune control of CMV**

the pathogenic pathways initiated by the murine and human viruses must be subtly

3. Without<\$%&?>external<\$%&?>immunosuppression,<\$%&?>adult<\$%&?>laboratory<\$%&?>mice<\$%&?>of<\$%&?>susce ptible<\$%&?>strains<\$%&?>can<\$%&?>readily<\$%&?>be<\$%&?>infected<\$%&?>with<\$%&?>murine<\$%&?>CMV<\$%&?>at<\$%& ?>a<\$%&?>dose<\$%&?>that<\$%&?>destroys<\$%&?>their<\$%&?>spleen<\$%&?>and<\$%&?>other<\$%&?>organs,<\$%&?>and<\$%&?

\$%&?>been<\$%&?>used<\$%&?>in<\$%&?>many<\$%&?>studies<\$%&?>to<\$%&?>examine<\$%&?>immune<\$%&?>responses<\$%&?

**2.** Susceptibility to murine CMV is MHC (murine *H-2*) dependent. This is evident in cultured cells and immunodeficient hosts so it is not related to CD8+ T-cell responses. Rather some *H-2* Class I proteins appear to act as a cell surface receptor. There is no evidence that human

**3.** Without external immunosuppression, adult laboratory mice of susceptible strains can readily be infected with murine CMV at a dose that destroys their spleen and other organs, and may cause death [4].This is not seen in people, but has been used in many studies to

**4.** *In vitro* infection of monocytes, macrophages and dendritic cells with murine CMV [8, 9] creates cells which remain intact but selectively loose secondary functions. This is interesting but not an important mode of immunoregulation, as only a small percentage

%&?>but<\$%&?>CMV<\$%&?>may<\$%&?>never<\$%&?>be<\$%&?>cleared<\$%&?>so<\$%&?>long-

f<\$%&?>the<\$%&?>lifetime<\$%&?>effects<\$%&?>of<\$%&?>CMV<\$%&?>on<\$%&?>human<\$%&?>health<\$%&?>-

Immune activation

CMV reactivation

cell<\$%&?>and<\$%&?>antibody<\$%&?>responses<\$%&?>may<\$%&?>reflect<\$%&?>CMV<\$%&?>replication<\$%&?>rather<\$%&?>

cell<\$%&?>responses<\$%&?>to<\$%&?>CMV<\$%&?>can<\$%&?>be<\$%&?>assessed<\$%&?>by<\$%&?>IFNγ<\$%&?>ELISpot<\$%&?> or<\$%&?>using<\$%&?>tetramers<\$%&?>or<\$%&?>pentamers<\$%&?>that<\$%&?>mark<\$%&?>cells<\$%&?>reacting<\$%&?>with<\$ %&?>a<\$%&?>particular<\$%&?>CMV<\$%&?>peptide<\$%&?>presented<\$%&?>by<\$%&?>a<\$%&?>particular<\$%&?>HLA<\$%&?>

cells<\$%&?>were<\$%&?>significantly<\$%&?>higher<\$%&?>in<\$%&?>immunosuppressed<\$%&?>transplant<\$%&?>recipients<\$%

A2).<\$%&?>Gamadia*<\$%&?>et<\$%&?>al*<\$%&?>[12]reported<\$%&?>that<\$%&?>frequencies<\$%&?>of<\$%&?>CMV-

To avoid translational issues between studies of MCMV in mice and HCMV in humans, we need to look more closely at people infected with CMV. This must include primary disease and the effects of long term asymptomatic CMV infection in immune competent hosts. A lesson that we can take from MCMV is the effects on multiple cells and organs, including the adrenals, pancreas and salivary glands [4, 5, 10, 11]. Sensitive PCR-based viral load assays are now available, but these are only routinely applied to blood, urine or saliva of patients at risk of acute disease. There is little probability of detecting latent CMV. Here we present a tool to evaluate the lifetime effects of CMV on human health - the footprint of CMV. We also sum‐ marise evidence that natural killer (NK) cells may regulate the footprint of CMV. The likely

11].<\$%&?>Sensitive<\$%&?>PCR-

MV<\$%&?>and<\$%&?>thereby<\$%&?>promote<\$%&?>cardiovascular<\$%&?>disease.

**Figure 1.** HIV disease has several avenues to enhance the footprint of CMV and thereby promote cardiovascular disease.

**HIV disease** 

CMV replication

Increase in quantity of CMV antigen boosts immune responses to CMV

**2.<\$%&?>Immune<\$%&?>control<\$%&?>of<\$%&?>CMV** 

than<\$%&?>protect<\$%&?>against<\$%&?>it.<\$%&?>CD8+<\$%&?>T-

molecule<\$%&?>(usually<\$%&?>HLA-

specific<\$%&?>CD8+<\$%&?>T-

of cells of these lineages are infected in patients or more resistant mice.

Poor T-cell responses able to control CMV

T-cell senescence

different. This has been demonstrated with CMV-encoded chemokines [6].

ls<\$%&?>with<\$%&?>murine<\$%&?>CMV<\$%&?>[8,

HLA proteins have this role [7].

rtant.

78 Manifestations of Cytomegalovirus Infection

>to<\$%&?>CMV.

examine immune responses to CMV.

s<\$%&?>[4,<\$%&?>5,

10,

impact in HIV patients is presented as Figure 1.

Thymic atrophy

Cardiovascular disease

%&?>1.

T-

4. *In<\$%&?>vitro*<\$%&?>infection<\$%&?>of<\$%&?>monocytes,<\$%&?>macrophages<\$%&?>and<\$%&?>dendritic<\$%&?>cel 9]<\$%&?>creates<\$%&?>cells<\$%&?>which<\$%&?>remain<\$%&?>intact<\$%& ?>but<\$%&?>selectively<\$%&?>loose<\$%&?>secondary<\$%&?>functions.<\$%&?>This<\$%&?>is<\$%&?>interesting<\$%&?>but<\$% &?>not<\$%&?>an<\$%&?>important<\$%&?>mode<\$%&?>of<\$%&?>immunoregulation,<\$%&?>as<\$%&?>only<\$%&?>a<\$%&?>sma ll<\$%&?>percentage<\$%&?>of<\$%&?>cells<\$%&?>of<\$%&?>these<\$%&?>lineages<\$%&?>are<\$%&?>infected<\$%&?>in<\$%&?>pati ents<\$%&?>or<\$%&?>more<\$%&?>resistant<\$%&?>mice.<\$%&?>Hence<\$%&?>their<\$%&?>loss<\$%&?>is<\$%&?>not<\$%&?>impo To<\$%&?>avoid<\$%&?>these<\$%&?>issues,<\$%&?>we<\$%&?>need<\$%&?>to<\$%&?>look<\$%&?>more<\$%&?>closely<\$%&?>at<\$ %&?>people<\$%&?>infected<\$%&?>with<\$%&?>CMV.<\$%&?>This<\$%&?>must<\$%&?>include<\$%&?>primary<\$%&?>disease,<\$ term<\$%&?>effects<\$%&?>may<\$%&?>impact<\$%&?>on<\$%&?>more<\$%&?>people.<\$%&?>A<\$%&?>lesson<\$%&?>that<\$%&?> we<\$%&?>can<\$%&?>take<\$%&?>from<\$%&?>MCMV<\$%&?>is<\$%&?>the<\$%&?>effects<\$%&?>on<\$%&?>multiple<\$%&?>cells< T-cell and antibody responses may reflect CMV replication rather than protect against it. CD8+ T-cell responses to CMV can be assessed by IFNγ ELISpot or using tetramers or pentamers that mark cells reacting with a particular CMV peptide presented by a particular HLA molecule (usually HLA-A2). Gamadia *et al* [12]reported that frequencies of CMV-specific CD8+ T-cells were significantly higher in immunosuppressed transplant recipients than in healthy donors, suggesting that these responses may reflect exposure rather than protection. This is consistent with evidence that CMV encodes proteins that down regulate T-cell recognition of infected cells, and thus evade immune detection. This includes the degradation of HLA class I and II molecules by unique short (US) proteins and disruption of antigen processing by an infected antigen-presenting cell [13].CMV-specific cells predominantly have an effector-memory or senescent phenotype (CD45R0+ CD27<sup>−</sup> CCR7<sup>−</sup> or CD45RA+ CD27<sup>−</sup> CCR7<sup>−</sup> , resp.). Subsequent studies suggest that a rapid CD4+ T-cell response was also essential to avoid symptomatic primary CMV infection in renal transplant recipients [14], but the cells critical for the mainte‐ nance of latency have not been identified.

\$%&?>and<\$%&?>organs,<\$%&?>including<\$%&?>the<\$%&?>adrenals,<\$%&?>pancreas<\$%&?>and<\$%&?>salivary<\$%&?>gland based<\$%&?>viral<\$%&?>load<\$%&?>assays<\$%&?>are<\$%&?>now<\$%&?>available,<\$%&?>but<\$%&?>these<\$%&?>are<\$%&?> only<\$%&?>routinely<\$%&?>applied<\$%&?>to<\$%&?>blood,<\$%&?>urine<\$%&?>or<\$%&?>saliva<\$%&?>of<\$%&?>patients<\$%& ?>at<\$%&?>risk<\$%&?>of<\$%&?>acute<\$%&?>disease.<\$%&?>There<\$%&?>is<\$%&?>little<\$%&?>probability<\$%&?>of<\$%&?>de tecting<\$%&?>latent<\$%&?>CMV.<\$%&?>Here<\$%&?>we<\$%&?>present<\$%&?>a<\$%&?>tool<\$%&?>to<\$%&?>evaluate<\$%&?>o <\$%&?>the<\$%&?>footprint<\$%&?>of<\$%&?>CMV.<\$%&?>We<\$%&?>also<\$%&?>summarise<\$%&?>evidence<\$%&?>that<\$%&? >natural<\$%&?>killer<\$%&?>(NK)<\$%&?>cells<\$%&?>may<\$%&?>regulate<\$%&?>the<\$%&?>footprint<\$%&?>of<\$%&?>CMV.<\$ %&?>The<\$%&?>likely<\$%&?>impact<\$%&?>in<\$%&?>HIV<\$%&?>patients<\$%&?>is<\$%&?>presented<\$%&?>as<\$%&?>Figure<\$ Extensive studies of MCMV infection in laboratory mice have mapped protective NK cellmediated responses to the Ly49 gene cluster [equivalent to human Killer Cell Immunoglobu‐ lin-like receptor (KIR) genes]. Mouse strains have distinct Ly49 gene repertoires, which correlate with resistance to MCMV [15]. The activating receptor Ly49H is implicated in protection, and several members of the Ly49 family interact with MCMV encoded proteins [16]. In mice without a protective NK response (eg: through Ly49H), MCMV infections are eventually controlled by T-cells. CD4+ T-cells are needed to control MCMV persistence in the salivary gland [17]. CD8+ T-cells recognising immediate early (IE) epitopes are also implicated in control of reactivated MCMV, where frequent boosting expands specific CD8+ T-cell clones. MCMV encodes genes able to regulate MHC class I expression, demonstrating an evolutionary impetus to avoid CD8+ T-cell responses. Critical epitopes and *H-2* loci initiating protective CD8+ T-cell responses have been identified, but it is a limitation that all studies use laboratory strains of MCMV rather than primary isolates [18]. This highlights the need to study human CMV disease.

> Direct evidence that NK cells can control CMV in humans is available from a study of a congenitally T-cell deficient child with acute CMV infection and a 10-fold expansion of NK cells with restricted receptor diversity. Acute illness resolved and NK cells returned to normal levels with clearance of plasma CMV DNA [19].This fits teleological and genetic evidence that NK cells control CMV. Human and mouse CMV diverged with their host species and have independently evolved proteins able to subvert protective NK responses [20]. This includes homologues of HLA-G (UL18) and HLA-E signal peptide (UL40), which interact with NK inhibitory receptors (LIR-1 and NKG2C, resp.) (Reviewed in[21] ) In support of a role for NK cells in CMV and HIV disease, we showed that heterozygous carriage of allele 2 at LIR-1 (rs1061680; LILRB1 I142T) associated with CMV disease and nadir CD4+ T-cell counts [22].

Figure 1. HIV<\$%&?>disease<\$%&?>has<\$%&?>several<\$%&?>avenues<\$%&?>to<\$%&?>enhance<\$%&?>the<\$%&?>footprint<\$%&?>of<\$%&?>C A role for NK cells in the control of CMV is also consistent with evidence that carriage of more genes for activating KIR receptors protects against CMV reactivation in immunosuppressed renal [23, 24] and bone marrow [25, 26] transplant patients. KIR receptors in man comprise both inhibitory and activating members (as do Ly49 genes in mice). The ligands for most inhibitory KIR are allelic epitopes of the classical class I HLA proteins (reviewed in[27]). In contrast, ligands for most of the activating KIR are unknown. An exception is KIR2DS1, which interacts with HLA-C2. [28, 29]. Several groups have attempted to identify the CMV-protective KIR gene, but this is complicated by linkage disequilibrium in the KIR gene complex. Inhibition of NK killing of fibroblasts infected by CMV has been demonstrated by several groups [30].This study implicated UL18 but this may depend on the NK donor's genotype. Although the roles of specific NK receptors in CMV disease are unclear, increased expression of LIR-1 [31, 32] and/or NKG2C [33, 34] is a consequence (footprint) of CMV replication. This has potential as a tool to assess a history of CMV reactivation.

Active CMV infection has been associated with the onset of autoimmune disorders in trans‐ plant patients and healthy donors. The development of autoimmune antibodies following re‐ activation of CMV in transplant patients has been linked to graft versus host disease and graft rejection. Hypergammaglobulinemia and autoantibody production can also be a feature of CMV-induced mononucleosis. There have been several case reports of healthy individuals de‐ veloping acute CMV infection preceding vasculitis or encephalitis. In a case of encephalitis, treatment of active CMV with valganciclovir resolved symptoms, but CMV-specific CD4+

 T-cells remained 10 months after disease onset [44-]. The development of autoimmune vasculitis, systemic lupus erythematosus, sclerodoma and necrotizing vasculitis have been as‐ sociated with CMV replication [46]. Anti-phospholipid antibodies have been shown to activate endothelial cells and CMV transcription [47], suggesting a feedback amplification loop.

CMV seropositivity has been correlated with a greater risk of all-cause mortality in the elderly [48-]. Although it is rare for CMV to be identified as the primary cause of death, CMV prevalence in the older population can be as high as 100% [52]. An in-depth study following Latinos aged 60-101 years for a period of 9 years (n=1,468) showed that those with high CMV antibody titres were 1.43 times more likely to die and had 1.35 times greater risk of CVDassociated mortality than those with low CMV antibody titres [51]. 96% of the participants were CMV seropositive. Factors significantly (p<0.05) associated with mortality included age, female gender, low education level and levels of inflammatory markers (TNF, IL-6, C-reactive protein). Elderly CMV-seropositive patients respond less well to seasonal influenza vaccina‐ tion than those with low or negative CMV seropositivity [50, 53]. This suggests dysfunction of

the immune system and could account for the increased risk of all-cause mortality.

example, NLV peptide-specific CD8+

show a senescent phenotype [54].

In older CMV-seropositive adults, up to 23% of the T-cell population can be CMV-specific. For

negative(an immunosenescent phenotype also associated with expression of CD57 and shortened telomeres) and have limited proliferative potential, but may produce IFNγ. Their accumulation correlates with immunologic aging or ''immunosenescence'' evident in the entire T-cell population assayed *ex vivo* [54-].The accumulation of senescent CMV-reactive Tcells was greatest in frail and institutionalized elderly donors [58].Repeated sub-clinical CMV infections may expand CMV-specific T-cells clones until they suppress homeostatic expansion of other T-cells. Alternatively the expanded clones of CMV-reactive cells may bias the population and dilute cells of other specificities - explaining why EBV-reactive T-cells do not

However chronic CMV reactivation may have wider consequences than just an aging immune system. CMV infects endothelial cells in acute stages of infection and it is proposed they could also be a site of latent infection [59, 60]. Studies of murine CMV in mice have identified endothelial cells as a site of viral latency [61], whilst several studies demonstrated human CMV in arterial walls of atherosclerotic and non-atherosclerotic patients [62, 63]. A study of tissues removed during surgery for abdominal aortic aneurysm associated the presence of CMV DNA in smooth muscle cells with expression of inflammatory mediators and implicated CMV in the pathology [64]. Accordingly higher CMV antibody titres are associated with increased diastolic and systolic blood pressure in young men [65] and CMV seropositivity is more frequent in

T-cells in donors aged 90 [89-96] years. CMV-specific T-cells are generally CD28-

T-cells alone comprised a median 3% (range = 0.4-5.6%)

CD8+

of CD8+

and

81

The Footprint of CMV Infection May Last a Lifetime

http://dx.doi.org/10.5772/54798

#### **3. CMV has a footprint in healthy aging and cardiovascular disease**

Associations between CMV and vasculopathy have been described since 1987 [35] and attributed to immunopathological events initiated by viral replication. Our studies of MCMV in inbred mice showed that susceptible BALB/c mice develop myocarditis in which CD8+ Tcells accumulate in the myocardium and persist for 12 months despite clearance of viral antigen by day 3 [36]. In C57BL/6 mice have a protective NK response [5] and display only mild resolving myocarditis. To evaluate the evidence available in patients requires consideration of the underlying mechanisms.

Inflammation and activation of immune cells features throughout atherogenic plaque forma‐ tion, which is the principle condition of cardiovascular disease (CVD). Pathogenesis of atherosclerotic plaques on vessel walls begins with acute inflammation resulting in endothe‐ lium dysfunction [37]. Many life-style risk factors can reduce the integrity of endothelium. The accumulation of low density lipoproteins (LDL) in intimal space by diffusion and its oxidation can cause endothelial cell injury and inflammation [38]. Secretion of vascular cell adhesion molecule-1 (VCAM-1) and up-regulation of selectins and integrins facilitates leukocyte adhesion to vessel walls. Inflammatory cytokines such as IL-1 and TNF-α induce expression of chemokines (eg: CCL2, CXCL8, CX3CL1) by endothelial cells, recruiting T-cells and monocytes and facilitating their transmigration into the intimal space. Monocytes internalize LDL and differentiate into macrophages which promote inflammation and leukocyte migra‐ tion into developing plaques by secretion of CX3CL1/CX3CR1, interferon-γ (IFNγ) and CCL2 [39, 40] and generation of reactive oxygen species [41]. Hyperlipidemia, macrophage death and consequential irregular surfaces of vessel endothelium promote growth of the athero‐ sclerotic lesion. Smooth muscle cells migrate from the media to intimal space aided by lytic enzymes. This contributes to plaque instability [39]. Smooth muscle cells proliferate in intimal space and also adhere to monocytes [42], thickening arterial walls and occluding the vessel. Rupture of the plaque can result in infarction. Myocardial infarcts (MI) refer to rupture of plaque in the coronary artery. The carotid artery is also a frequent site of plaque formation and thickness of the intima at this site can indicate clinical and sub-clinical CVD [43].

Active CMV infection has been associated with the onset of autoimmune disorders in trans‐ plant patients and healthy donors. The development of autoimmune antibodies following re‐ activation of CMV in transplant patients has been linked to graft versus host disease and graft rejection. Hypergammaglobulinemia and autoantibody production can also be a feature of CMV-induced mononucleosis. There have been several case reports of healthy individuals de‐ veloping acute CMV infection preceding vasculitis or encephalitis. In a case of encephalitis, treatment of active CMV with valganciclovir resolved symptoms, but CMV-specific CD4+ and CD8+ T-cells remained 10 months after disease onset [44-]. The development of autoimmune vasculitis, systemic lupus erythematosus, sclerodoma and necrotizing vasculitis have been as‐ sociated with CMV replication [46]. Anti-phospholipid antibodies have been shown to activate endothelial cells and CMV transcription [47], suggesting a feedback amplification loop.

renal [23, 24] and bone marrow [25, 26] transplant patients. KIR receptors in man comprise both inhibitory and activating members (as do Ly49 genes in mice). The ligands for most inhibitory KIR are allelic epitopes of the classical class I HLA proteins (reviewed in[27]). In contrast, ligands for most of the activating KIR are unknown. An exception is KIR2DS1, which interacts with HLA-C2. [28, 29]. Several groups have attempted to identify the CMV-protective KIR gene, but this is complicated by linkage disequilibrium in the KIR gene complex. Inhibition of NK killing of fibroblasts infected by CMV has been demonstrated by several groups [30].This study implicated UL18 but this may depend on the NK donor's genotype. Although the roles of specific NK receptors in CMV disease are unclear, increased expression of LIR-1 [31, 32] and/or NKG2C [33, 34] is a consequence (footprint) of CMV replication. This has potential as

**3. CMV has a footprint in healthy aging and cardiovascular disease**

Associations between CMV and vasculopathy have been described since 1987 [35] and attributed to immunopathological events initiated by viral replication. Our studies of MCMV in inbred mice showed that susceptible BALB/c mice develop myocarditis in which CD8+ Tcells accumulate in the myocardium and persist for 12 months despite clearance of viral antigen by day 3 [36]. In C57BL/6 mice have a protective NK response [5] and display only mild resolving myocarditis. To evaluate the evidence available in patients requires consideration of

Inflammation and activation of immune cells features throughout atherogenic plaque forma‐ tion, which is the principle condition of cardiovascular disease (CVD). Pathogenesis of atherosclerotic plaques on vessel walls begins with acute inflammation resulting in endothe‐ lium dysfunction [37]. Many life-style risk factors can reduce the integrity of endothelium. The accumulation of low density lipoproteins (LDL) in intimal space by diffusion and its oxidation can cause endothelial cell injury and inflammation [38]. Secretion of vascular cell adhesion molecule-1 (VCAM-1) and up-regulation of selectins and integrins facilitates leukocyte adhesion to vessel walls. Inflammatory cytokines such as IL-1 and TNF-α induce expression of chemokines (eg: CCL2, CXCL8, CX3CL1) by endothelial cells, recruiting T-cells and monocytes and facilitating their transmigration into the intimal space. Monocytes internalize LDL and differentiate into macrophages which promote inflammation and leukocyte migra‐ tion into developing plaques by secretion of CX3CL1/CX3CR1, interferon-γ (IFNγ) and CCL2 [39, 40] and generation of reactive oxygen species [41]. Hyperlipidemia, macrophage death and consequential irregular surfaces of vessel endothelium promote growth of the athero‐ sclerotic lesion. Smooth muscle cells migrate from the media to intimal space aided by lytic enzymes. This contributes to plaque instability [39]. Smooth muscle cells proliferate in intimal space and also adhere to monocytes [42], thickening arterial walls and occluding the vessel. Rupture of the plaque can result in infarction. Myocardial infarcts (MI) refer to rupture of plaque in the coronary artery. The carotid artery is also a frequent site of plaque formation and

thickness of the intima at this site can indicate clinical and sub-clinical CVD [43].

a tool to assess a history of CMV reactivation.

80 Manifestations of Cytomegalovirus Infection

the underlying mechanisms.

CMV seropositivity has been correlated with a greater risk of all-cause mortality in the elderly [48-]. Although it is rare for CMV to be identified as the primary cause of death, CMV prevalence in the older population can be as high as 100% [52]. An in-depth study following Latinos aged 60-101 years for a period of 9 years (n=1,468) showed that those with high CMV antibody titres were 1.43 times more likely to die and had 1.35 times greater risk of CVDassociated mortality than those with low CMV antibody titres [51]. 96% of the participants were CMV seropositive. Factors significantly (p<0.05) associated with mortality included age, female gender, low education level and levels of inflammatory markers (TNF, IL-6, C-reactive protein). Elderly CMV-seropositive patients respond less well to seasonal influenza vaccina‐ tion than those with low or negative CMV seropositivity [50, 53]. This suggests dysfunction of the immune system and could account for the increased risk of all-cause mortality.

In older CMV-seropositive adults, up to 23% of the T-cell population can be CMV-specific. For example, NLV peptide-specific CD8+ T-cells alone comprised a median 3% (range = 0.4-5.6%) of CD8+ T-cells in donors aged 90 [89-96] years. CMV-specific T-cells are generally CD28 negative(an immunosenescent phenotype also associated with expression of CD57 and shortened telomeres) and have limited proliferative potential, but may produce IFNγ. Their accumulation correlates with immunologic aging or ''immunosenescence'' evident in the entire T-cell population assayed *ex vivo* [54-].The accumulation of senescent CMV-reactive Tcells was greatest in frail and institutionalized elderly donors [58].Repeated sub-clinical CMV infections may expand CMV-specific T-cells clones until they suppress homeostatic expansion of other T-cells. Alternatively the expanded clones of CMV-reactive cells may bias the population and dilute cells of other specificities - explaining why EBV-reactive T-cells do not show a senescent phenotype [54].

However chronic CMV reactivation may have wider consequences than just an aging immune system. CMV infects endothelial cells in acute stages of infection and it is proposed they could also be a site of latent infection [59, 60]. Studies of murine CMV in mice have identified endothelial cells as a site of viral latency [61], whilst several studies demonstrated human CMV in arterial walls of atherosclerotic and non-atherosclerotic patients [62, 63]. A study of tissues removed during surgery for abdominal aortic aneurysm associated the presence of CMV DNA in smooth muscle cells with expression of inflammatory mediators and implicated CMV in the pathology [64]. Accordingly higher CMV antibody titres are associated with increased diastolic and systolic blood pressure in young men [65] and CMV seropositivity is more frequent in coronary artery disease requiring surgery[66]. Increased expression of LIR-1 on NK cells (a footprint of CMV) is also associated with atherosclerosis [67].Stronger T-cell responses to CMV also associate with severe cardiovascular changes seen in HIV patients [68].

to ART) than in the general population. This includes cardiovascular disease – which is influenced by the ART regime, life-style factors (smoking, exercise etc.) and other infections, notably CMV. CMV infection is more prominent in HIV patients, so its role in immunological

The Footprint of CMV Infection May Last a Lifetime

http://dx.doi.org/10.5772/54798

83

Over 50% of healthy individuals and 90% of individuals living with HIV are seropositive for CMV. Retinitis is the most common manifestation of CMV disease in HIV-infected individuals, affecting up to 40% of American AIDS patients, and many HIV patients in the developing world [3, 79].Treatment of systemic CMV disease is expensive and protracted, so prophylaxis is suspended once patients are stable on ART. As discussed earlier, CMV has the capacity for latency with frequent reactivation triggered by inflammatory mediators, including TNF [80]. Immune activation in treated and untreated HIV disease increases levels of this cytokine in

It appears likely that CMV and thymic insufficiency are synergistic in their effects on T-cell profiles in HIV patients. This is supported by evidence that homeostatic expansion of existing T-cells maintains T-cell numbers in the absence of thymic output, so age-related declines in immune function are accentuated in patients thymectomised in early childhood. This was clearest in individuals with strong T-cell responses to CMV IE and pp65 antigens [82].Accu‐ mulation of CMV –specific T-cells with an immunosenescent phenotype is greater in HIV patients than in age-matched controls [83, 84]. The importance of CMV in immune activation and immunosenesence in HIV patients is confirmed by evidence that immune activation was

Our studies of HIV patients also suggest that elevated T-cell and humoral responses to CMV reflect frequent reactivation. We investigated HIV patients who began antiretroviral therapy (ART) with extreme immunodeficiency and maintained a virological response until they were >50 years old. One can assume that they had a high burden of CMV pre-ART as many had experienced CMV retinitis. These HIV patients retained high titres of antibody reactive with CMV after 14 [13-16] years on ART and displayed elevated IFNγ responses to an immediate early peptide of CMV*(unpublished data).*Such patients display accelerated cardiovascular

CD4+CX3CR1+ T-cells may help explain the role of CMV-specific cells in development of atherosclerosis in HIV patients, but the mechanisms requires further investigation. Interest in

**1.** Atherosclerosis is an inflammatory disease that is more frequent in HIV patients and

A study of CX3CR1+ CD4+ T-cells and their implications in CVD was conducted in HIV-

correlated with increasing carotid intima-media thickness (cIMT) in HIV-infected individuals.

CX3CR1+ T-cells

CX3CR/L in atherosclerosis is focussed by three findings reported in several studies.

cannot be attributed to ART cardiotoxicity alone [87, 88, 89, 90, 91].

**2.** HIV patients have a high proportion of CMV-specific T-cells [82, 83, 92]

infected (n=29) and uninfected (n=48) individuals. The frequency of CD4+

**3.** CX3CR1 is found in atherosclerotic lesions and is expressed by T-cells [69,70]

circulation and tissues [81], so frequent subclinical reactivation of CMV is expected.

aging and cardiovascular disease requires evaluation [78].

reduced when patients were treated with valgancyclovir [85].

disease that correlates with responses to CMV [86].

The chemokine, fractalkine (CX3CL1) and its receptor CX3CR1 are membrane-bound proteins. CX3CL1 can be cleaved from a cell surface through TNFα signal pathways to mediate attraction and then firm adhesion of lymphocytes expressing CX3CR1 to endothelium. T-lymphocytes and monocytes express CX3CR1, whilst monocytes, endothelial cells and smooth muscle cells can be induced to express CX3CL1 by TNFα, IFNγ, IL-1 and LPS [37, 69, 70].CX3CR1 is found in atherosclerotic plaques and its role in plaque formation and mediation by inflammation is of interest in the management of CVD [69]. An *in vitro* system co-coculturing CMV infected endothelial cells and peripheral blood mononuclear cells established the principle that CMV specific CD4*+* T-cells can induce CX3CL1 production in CMV infected endothelial cells. CX3CL1 aids the ingress of monocytes and NK cells which are capable of killing the CMV infected endothelial cell [71].

Monocytes in atherosclerotic plaques express higher levels of CX3CR1 and CX3CL1 promoting chemotaxis of monocytes and T-lymphocytes to the plaque [72].CX3CL1 can be expressed by epithelial cells, but vascular endothelial cells and smooth muscle cells do not normally express CX3CL1. TNFα can induce expression of CX3CR1/L1 in these tissues [70], which corresponds with detection of CX3CR1/L1 at a later stage of plaque formation. Sacre *et al*. reported that CD4+ CX3CR1+ T-cells produced more TNFα and IFN γ *in vitro* than CD4+ CX3CR1- T-cells. This is consistent with a potential feedback mechanism in which CD4+ CX3CR1+ T-cells exacerbate plaque formation. Immuno-histochemical staining of coronary arterial wall samples from HIV patients with atherosclerosis showed a presence of CX3CR1, CD4 and CD3 at *early* stages of atherogenesis, so CD4+ CX3CR1+ T-cells could initiate plaque formation [73].

#### **4. HIV patients stable on ART have a stronger footprint of CMV**

In HIV patients with suppressed HIV replication on ART, the recovery of CD4+ T-cell counts is limited by replenishment from the thymus and the loss of T-cells through persistent chronic immune activation [74, 75].Persistent CD4+ T-cell deficiency is most common in patients with low nadir CD4+ T-cell counts (<100 cells/μl) even though some patients beginning ART with severe T-cell depletion achieve effective immune reconstitution [76]. Patients with abundant thymic tissue show a faster and higher return of naïve CD4+ T-cells after ART. However the thymus is a site of HIV replication. Infected thymocytes may die (through necrosis or apop‐ tosis) or survive and carry the HIV provirus to their progenies (establishing latent infection). As HIV disease progresses, the thymus becomes prematurely atrophic, with changes similar to those seen in old age. For example, the thymus of a 30 year-old with late stage AIDS may be morphologically similar to the normal atrophic thymus of a 60 year-old [77].

Thymic dysfunction and the consequent release of autoreactive T-cells into circulation are implicated in the autoimmune and immunopathological conditions normally seen in old age - conditions that are more common in HIV patients (including those with a virological response to ART) than in the general population. This includes cardiovascular disease – which is influenced by the ART regime, life-style factors (smoking, exercise etc.) and other infections, notably CMV. CMV infection is more prominent in HIV patients, so its role in immunological aging and cardiovascular disease requires evaluation [78].

coronary artery disease requiring surgery[66]. Increased expression of LIR-1 on NK cells (a footprint of CMV) is also associated with atherosclerosis [67].Stronger T-cell responses to CMV

The chemokine, fractalkine (CX3CL1) and its receptor CX3CR1 are membrane-bound proteins. CX3CL1 can be cleaved from a cell surface through TNFα signal pathways to mediate attraction and then firm adhesion of lymphocytes expressing CX3CR1 to endothelium. T-lymphocytes and monocytes express CX3CR1, whilst monocytes, endothelial cells and smooth muscle cells can be induced to express CX3CL1 by TNFα, IFNγ, IL-1 and LPS [37, 69, 70].CX3CR1 is found in atherosclerotic plaques and its role in plaque formation and mediation by inflammation is of interest in the management of CVD [69]. An *in vitro* system co-coculturing CMV infected endothelial cells and peripheral blood mononuclear cells established the principle that CMV specific CD4*+* T-cells can induce CX3CL1 production in CMV infected endothelial cells. CX3CL1 aids the ingress of monocytes and NK cells which are capable of killing the CMV

Monocytes in atherosclerotic plaques express higher levels of CX3CR1 and CX3CL1 promoting chemotaxis of monocytes and T-lymphocytes to the plaque [72].CX3CL1 can be expressed by epithelial cells, but vascular endothelial cells and smooth muscle cells do not normally express CX3CL1. TNFα can induce expression of CX3CR1/L1 in these tissues [70], which corresponds with detection of CX3CR1/L1 at a later stage of plaque formation. Sacre *et al*. reported that

plaque formation. Immuno-histochemical staining of coronary arterial wall samples from HIV patients with atherosclerosis showed a presence of CX3CR1, CD4 and CD3 at *early* stages of

is limited by replenishment from the thymus and the loss of T-cells through persistent chronic immune activation [74, 75].Persistent CD4+ T-cell deficiency is most common in patients with low nadir CD4+ T-cell counts (<100 cells/μl) even though some patients beginning ART with severe T-cell depletion achieve effective immune reconstitution [76]. Patients with abundant

thymus is a site of HIV replication. Infected thymocytes may die (through necrosis or apop‐ tosis) or survive and carry the HIV provirus to their progenies (establishing latent infection). As HIV disease progresses, the thymus becomes prematurely atrophic, with changes similar to those seen in old age. For example, the thymus of a 30 year-old with late stage AIDS may

Thymic dysfunction and the consequent release of autoreactive T-cells into circulation are implicated in the autoimmune and immunopathological conditions normally seen in old age - conditions that are more common in HIV patients (including those with a virological response

T-cells could initiate plaque formation [73].

CX3CR1-

T-cells after ART. However the

CX3CR1+

T-cells. This

T-cell counts

T-cells exacerbate

T-cells produced more TNFα and IFN γ *in vitro* than CD4+

**4. HIV patients stable on ART have a stronger footprint of CMV**

In HIV patients with suppressed HIV replication on ART, the recovery of CD4+

be morphologically similar to the normal atrophic thymus of a 60 year-old [77].

is consistent with a potential feedback mechanism in which CD4+

CX3CR1+

thymic tissue show a faster and higher return of naïve CD4+

also associate with severe cardiovascular changes seen in HIV patients [68].

infected endothelial cell [71].

82 Manifestations of Cytomegalovirus Infection

CD4+

CX3CR1+

atherogenesis, so CD4+

Over 50% of healthy individuals and 90% of individuals living with HIV are seropositive for CMV. Retinitis is the most common manifestation of CMV disease in HIV-infected individuals, affecting up to 40% of American AIDS patients, and many HIV patients in the developing world [3, 79].Treatment of systemic CMV disease is expensive and protracted, so prophylaxis is suspended once patients are stable on ART. As discussed earlier, CMV has the capacity for latency with frequent reactivation triggered by inflammatory mediators, including TNF [80]. Immune activation in treated and untreated HIV disease increases levels of this cytokine in circulation and tissues [81], so frequent subclinical reactivation of CMV is expected.

It appears likely that CMV and thymic insufficiency are synergistic in their effects on T-cell profiles in HIV patients. This is supported by evidence that homeostatic expansion of existing T-cells maintains T-cell numbers in the absence of thymic output, so age-related declines in immune function are accentuated in patients thymectomised in early childhood. This was clearest in individuals with strong T-cell responses to CMV IE and pp65 antigens [82].Accu‐ mulation of CMV –specific T-cells with an immunosenescent phenotype is greater in HIV patients than in age-matched controls [83, 84]. The importance of CMV in immune activation and immunosenesence in HIV patients is confirmed by evidence that immune activation was reduced when patients were treated with valgancyclovir [85].

Our studies of HIV patients also suggest that elevated T-cell and humoral responses to CMV reflect frequent reactivation. We investigated HIV patients who began antiretroviral therapy (ART) with extreme immunodeficiency and maintained a virological response until they were >50 years old. One can assume that they had a high burden of CMV pre-ART as many had experienced CMV retinitis. These HIV patients retained high titres of antibody reactive with CMV after 14 [13-16] years on ART and displayed elevated IFNγ responses to an immediate early peptide of CMV*(unpublished data).*Such patients display accelerated cardiovascular disease that correlates with responses to CMV [86].

CD4+CX3CR1+ T-cells may help explain the role of CMV-specific cells in development of atherosclerosis in HIV patients, but the mechanisms requires further investigation. Interest in CX3CR/L in atherosclerosis is focussed by three findings reported in several studies.


A study of CX3CR1+ CD4+ T-cells and their implications in CVD was conducted in HIVinfected (n=29) and uninfected (n=48) individuals. The frequency of CD4+ CX3CR1+ T-cells correlated with increasing carotid intima-media thickness (cIMT) in HIV-infected individuals. These cells were antigen primed (CD45RA- , CD27- ), activated (HLA-DR+) and immunosenes‐ cent (CD57+ ) [73].

**6. Conclusions**

The footprint may include

**3.** IFN-γ responses of CD4+

titres of CMV antibody.

**Author details**

Patricia Price

**References**

will benefit most from CMV prophylaxis.

University of Western Australia, Australia

col Therap 2003; 269-297

**4.** Anti-CMV antibody detected by ELISA

flow cytometry.

The immune response to CMV has been studied extensively in mice and evidence is now accumulating from studies in humans. It is clear that NK cell and T cell responses are both important and that they influence each other. We propose a "footprint of CMV" as a tool to

**2.** CMV-peptide/HLA tetramer positive CD8 T cells: The number of these cells in the blood is thought to reflect an accumulation of cells responding to CMV replication.

**5.** Expression of NKG2C and LIR-1 on NK cells and T cells: NKG2C is expressed on a very small proportion of NK cells in CMV-seronegative subjects but expressed on a substantial proportion of NK cells from CMV seropositive subjects [31,32,33]and is considered a hallmark of CMV exposure. This probably reflects expansion of a small NK cell population in response to CMV infection. LIR-1 expression is also increased in subjects with higher

The resulting holistic view of the immune response in man will be a foundation for future studies aimed at identifying phenotypes associated with protection and those individuals who

[1] Murphy E, Yu D, Grimwood J, Schmutz J, Dickson M, Jarvis MA, Hahn G, Nelson JA, Myers RM, Shenk TE. Coding potential of laboratory and clinical strains of human

[2] Landolfo S, Gariglio M, Gribaudo G, Lembo D. The human cytomegalovirus. Pharma‐

cytomegalovirus. Proc Natl Acad Sci USA, 2003; 100 14976-81.

and CD8+ T-cells to CMV antigens enumerated by ELISPOT or

The Footprint of CMV Infection May Last a Lifetime

http://dx.doi.org/10.5772/54798

85

investigate the short and long term effects of CMV infection.

**1.** CMV DNA detected by a sensitive PCR assay of blood, saliva or urine.

It may also be important that NK function is deficient in HIV patients. HIV infection changes the proportions of NK cell subsets, and expression of their activating and inhibitory receptors. It also perturbs their cytotoxic functions and cytokine production [93].Our group has publish‐ ed two studies of previously immunodeficient Australian patients, stabilised for many years on ART:


#### **5. CMV remains an important pathogen after renal transplantation**

CMV reactivation (in previously seropositive recipients) or primary infection (in any recipient) is the most common infectious complication in renal transplantation [96].In the 1970's one in three recipients experienced pathologies associated with CMV. In one study of 141 patients, 12 *died* with disseminated CMV infection [97, 98].

In Australia, prophylaxis (valganciclovir) is routinely administered for 12-26 weeks after transplantation, according to a formula that considers donor and recipient CMV seropositivity and clinical risk. Under an equivalent regime, CMV recurred in 14/43 (33%) seropositive patients and in 4/19 (21%) patients after primary infection [99]. CMV remains a significant cause of graft loss despite prophylaxis and in the longer term, CMV reactivations are impli‐ cated in deterioration in renal function [100, 101], exhaustion or senescence of T-cells and cardiovascular disease.

Cardiovascular disease is recognised as a long term complication of renal transplantation, but a recent review [102] attributed this to immunosuppression. CMV antigenaemia (pp65) in the first year post-transplant did not predict cardiovascular disease over the next 2 years [102], but the study did no assess the longer term footprint of CMV disease. It is notable that Gomez et al [103] associated cardiovascular disease with CMV seropositivity over 1 year posttransplant in patients given oral ganciclovir.

#### **6. Conclusions**

These cells were antigen primed (CD45RA-

) [73].

84 Manifestations of Cytomegalovirus Infection

cent (CD57+

on ART:

, CD27-

It may also be important that NK function is deficient in HIV patients. HIV infection changes the proportions of NK cell subsets, and expression of their activating and inhibitory receptors. It also perturbs their cytotoxic functions and cytokine production [93].Our group has publish‐ ed two studies of previously immunodeficient Australian patients, stabilised for many years

**1.** CD4+ T-cell IFNγ responses to CMV were *inversely* related to CD4+ T-cell counts before ART in patients who began ART with <60 CD4+ T-cells/μL, but IFNγ responses of NK cells to an unrestricted target (K562 cells) were *directly* proportional to nadir CD4+ T-cell counts [94].This establishes that NK cells don't follow the same trends as CD4+ T-cells on

correlated and lower in patients than controls (confirming persistent NK dysfunction). Proportions of CD56hiCD16neg NK cells (a phenotype associated with cytokine production) correlated inversely with CD4+ T-cell counts after ART and expression of perforin in this NK subset was *higher* in HIV patients than healthy controls. So these NK cells may

ART and do keep the imprint of the pre-ART immune system for many years.

**5. CMV remains an important pathogen after renal transplantation**

CMV reactivation (in previously seropositive recipients) or primary infection (in any recipient) is the most common infectious complication in renal transplantation [96].In the 1970's one in three recipients experienced pathologies associated with CMV. In one study of 141 patients,

In Australia, prophylaxis (valganciclovir) is routinely administered for 12-26 weeks after transplantation, according to a formula that considers donor and recipient CMV seropositivity and clinical risk. Under an equivalent regime, CMV recurred in 14/43 (33%) seropositive patients and in 4/19 (21%) patients after primary infection [99]. CMV remains a significant cause of graft loss despite prophylaxis and in the longer term, CMV reactivations are impli‐ cated in deterioration in renal function [100, 101], exhaustion or senescence of T-cells and

Cardiovascular disease is recognised as a long term complication of renal transplantation, but a recent review [102] attributed this to immunosuppression. CMV antigenaemia (pp65) in the first year post-transplant did not predict cardiovascular disease over the next 2 years [102], but the study did no assess the longer term footprint of CMV disease. It is notable that Gomez et al [103] associated cardiovascular disease with CMV seropositivity over 1 year post-

**2.** NK cell IFNγ responses and proportions of CD56loCD16+

compensate for T-cell deficiency [95].

12 *died* with disseminated CMV infection [97, 98].

transplant in patients given oral ganciclovir.

cardiovascular disease.

), activated (HLA-DR+) and immunosenes‐

NK cells were positively

The immune response to CMV has been studied extensively in mice and evidence is now accumulating from studies in humans. It is clear that NK cell and T cell responses are both important and that they influence each other. We propose a "footprint of CMV" as a tool to investigate the short and long term effects of CMV infection.

The footprint may include


The resulting holistic view of the immune response in man will be a foundation for future studies aimed at identifying phenotypes associated with protection and those individuals who will benefit most from CMV prophylaxis.

#### **Author details**

Patricia Price

University of Western Australia, Australia

#### **References**


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[93] Fauci AS, Mavilio D and Kottilil S. NK cells in HIV infection: paradigm for protection

[94] Price P, Fernandez S, Tan DB, James IR, Keane NM and French MA. Nadir CD4 T-cell counts continue to influence interferon-gamma responses in HIV patients who began antiretroviral treatment with advanced immunodeficiency. J Acquir Immune Defic‐

[95] Tan DB, Fernandez S, French M and Price P. Could natural killer cells compensate for impaired CD4+ T-cell responses to CMV in HIV patients responding to antiretroviral

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tissue in patients with HIV. Am Heart J. 2012 Jun;163(6):1024-30.

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key marker of systemic CD4+ T cell activation in HIV-infected individuals. J Immunol

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[77] Meissner EG, Duus KM, Loomis R, D'Agostin R and Su L. HIV-1 replication and

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[79] Heiden D, Ford N, Wilson D, Rodriguez WR, Margolis T, Janssens B, Bedelu M, Tun N, Goemaere E, Saranchuk P, Sabapathy K, Smithuis F, Luyirika E and Drew WL. Cytomegalovirus retinitis: the neglected disease of the AIDS pandemic. PLoS Med 2007;

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[81] Ownby RL, Kumar AM, Benny Fernandez J, Moleon-Borodowsky I, Gonzalez L, Eisdorfer S, Waldrop-Valverde D and Kumar M. Tumor necrosis factor-alpha levels in HIV-1 seropositive injecting drug users. J NeuroimmunePharmacol 2009; 4:350-8. [82] Sauce D, Larsen M, Fastenackels S, Duperrier A, Keller M, Grubeck-Loebenstein B, Ferrand C, Debre P, Sidi D and Appay V. Evidence of premature immune aging in patients thymectomized during early childhood. J Clin Invest 2009; 119:3070-8. [83] Stone SF, Price P and French MA. Cytomegalovirus (CMV)-specific CD8+ T cells in individuals with HIV infection: correlation with protection from CMV disease. J Anti

[84] Naeger DM, Martin JN, Sinclair E, Hunt PW, Bangsberg DR, Hecht F, Hsue P, McCune JM, Deeks SG. Cytomegalovirus-specific T cells persist at very high levels during longterm antiretroviral treatment of HIV disease. PLoS One. 2010 Jan 29;5(1):e8886. [85] Hunt PW, Martin JN, Sinclair E, Epling L, Teague J, Jacobson MA, Tracy RP, Corey L, Deeks SG. Valganciclovir reduces T cell activation in HIV-infected individuals with incomplete CD4+ T cell recovery on antiretroviral therapy. J Infect Dis. 2011 May

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**Chapter 6**

**The Oncogenicity of Human Cytomegalovirus**

The potential role of Human cytomegalovirus (hCM) infection in promoting neoplasia is an active area of scientific research. [1] Although still controversial, there is a growing body of evidence that links hCMV infection to a variety of malignancies, including those of the breast, prostate, colon, lung and brain (gliomas). [2-7] hCMV induces alterations in regulatory proteins and non-coding RNA that are associated with a malignant phenotype. These changes promote tumour survival by effecting cellular proliferation, invasion, immune evasion, and production of angiogenic factors [8] Constant immune surveillance governs the destruction of the majority of cancer cells and precancerous conditions in the human body. However, the most pathogenic of malignant tumors acquire immune evasion strategies which render them

In cancers which are not attributable to infectious agents, chronic inflammation may also play a critical role in the transition from a precancerous condition to invasive malignancy. Inflam‐ mation is the seventh hallmark of neoplasia (Table 1). [10] During chronic inflammation, certain "promoters," such as hepatitis C virus and Epstein-Barr virus (EBV), may facilitate the transformation of a pre-malignant condition to neoplasia. [11,12] Cancer "promoters" are agents that, by themselves, may not have a significant oncogenic impact on normal cells but

and reproduction in any medium, provided the original work is properly cited.

© 2013 Vishnu and Aboulafia; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

Prakash Vishnu and David M. Aboulafia

less vulnerable to destruction by immune cells.

can drive precancerous cells towards neoplasia.

The characteristic hallmarks of a malignant cell include:

**2.** resisting cell death and enabling replicative immortality,

**3.** inducing angiogenesis, activating invasion and metastasis. [9]

**1.** sustaining proliferative signaling and evading growth suppressors,

http://dx.doi.org/10.5772/55051

**1. Introduction**

Additional information is available at the end of the chapter


### **The Oncogenicity of Human Cytomegalovirus**

Prakash Vishnu and David M. Aboulafia

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/55051

#### **1. Introduction**

[98] Helanterä I, Lautenschlager I, Koskinen P. The risk of cytomegalovirus recurrence after

[99] Luan FL, Kommareddi M, Ojo AO. Impact of cytomegalovirus disease in D+/R- kidney transplant patients receiving 6 months low-dose valganciclovir prophylaxis. Am J

[100] Smith JM, Corey L, Bittner R, Finn LS, Healey PJ, Davis CL, McDonald RA. Subclinical viremia increases risk for chronic allograft injury in pediatric renal transplantation. J

[101] Tong CY, Bakran A, Peiris JS, Muir P, Herrington CS. The association of viral infection and chronic allograft nephropathy with graft dysfunction after renal transplantation.

[102] Jardine AG, Gaston RS, Fellstrom BC, Holdaas H. Prevention of cardiovascular disease in adult recipients of kidney transplants. Lancet. 2011 Oct 15;378(9800):1419-27.

[103] Gómez E, Laurés A, Baltar JM, Melón S, Díez B, de Oña M. Cytomegalovirus replication and "herpesvirus burden" as risk factor of cardiovascular events in the first year after

renal transplantation. Transplant Proc. 2005 Nov;37(9):3760-3.

kidney transplantation. Transpl Int. 2011 Dec;24(12):1170-8.

Transplant. 2011 Sep;11(9):1936-42.

94 Manifestations of Cytomegalovirus Infection

Am Soc Nephrol. 2010 Sep;21(9):1579-86.

Transplantation. 2002 Aug 27;74(4):576-8.

The potential role of Human cytomegalovirus (hCM) infection in promoting neoplasia is an active area of scientific research. [1] Although still controversial, there is a growing body of evidence that links hCMV infection to a variety of malignancies, including those of the breast, prostate, colon, lung and brain (gliomas). [2-7] hCMV induces alterations in regulatory proteins and non-coding RNA that are associated with a malignant phenotype. These changes promote tumour survival by effecting cellular proliferation, invasion, immune evasion, and production of angiogenic factors [8] Constant immune surveillance governs the destruction of the majority of cancer cells and precancerous conditions in the human body. However, the most pathogenic of malignant tumors acquire immune evasion strategies which render them less vulnerable to destruction by immune cells.

The characteristic hallmarks of a malignant cell include:


In cancers which are not attributable to infectious agents, chronic inflammation may also play a critical role in the transition from a precancerous condition to invasive malignancy. Inflam‐ mation is the seventh hallmark of neoplasia (Table 1). [10] During chronic inflammation, certain "promoters," such as hepatitis C virus and Epstein-Barr virus (EBV), may facilitate the transformation of a pre-malignant condition to neoplasia. [11,12] Cancer "promoters" are agents that, by themselves, may not have a significant oncogenic impact on normal cells but can drive precancerous cells towards neoplasia.

**Table 1.** The "seven" hallmarks of cancer

#### **2. Chronic inflammation and oncogenesis**

Associations linking chronic infection, chronic inflammation and malignancy have been well chronicled. [13] As many as 25% of all cancers can be traced to chronic infection or other types of chronic inflammation. [14] Infectious agents that cause chronic inflammation promote oncogenesis by complex pathways, and are depicted in Figure 1. Key mediators of inflamma‐ tion-induced oncogenesis include generation of mutagenic chemical mediators such as reactive oxygen and nitrogen species, genetic variations in inflammatory cytokines [15], and creation of a micro-environment with features of chronic inflammation such as nuclear factor kappa B (NF-κB). [16,17] In such conditions, tumor-associated macrophages (TAMs) play a pivotal role in mediating inflammatory (M1) responses, as well as immunosuppressive and growth (M2) responses. [18]

**3. Concept of oncomodulation**

which are modulated by hCMV are reviewed below.

**3.1. Resistance to apoptosis**

Tumor cells have aberrations in cell cycle signaling, RNA transcription and the production of tumor-suppression proteins. The concept of "oncomodulation" suggests that a virus may modulate cellular pathways [26] through changes to viral regulatory proteins and noncoding RNA which eludes to tumor cell properties (cell proliferation, survival, invasion, production of angiogenic factors, and immune evasion). hCMV not only promotes oncogenesis but also contributes to a more malignant tumor cell phenotype (Figure 2). While investigators have long postulated a role for hCMV in human neoplasia, many of the early studies were not reproducible and lacked clear *in situ* histopathological correlations with the proposed diseases. [27,28] The concept of "hit-and-run" oncogenesis holds that infection with hCMV takes place during an earlier time frame to tumour development. hCMV infection sets into motion processes resulting in malignancy, but the virus is no longer detectable by the time cancer occurs. [29] Several of the more important cellular pathways that could lead to cancer and

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97

**Figure 1.** Pathway linking chronic inflammation and oncogenesis. (Adapted from Schetter et. al. [13])

Resistance to apoptosis is a common feature of cancer cells. [9,30,31] Early research on hCMV infection revealed that hCMV protects the fibroblasts it infects from apoptosis. hCMV immediate early (IE) proteins (e.g., IE2-86 & IE2-72) [32] are able to prevent adenovirus E1A

M2-polarized TAMs and the related myeloid-derived suppressor cells are key components of smoldering inflammation that drives neoplastic progression. The M2 responses, while important for wound healing, can promote neoplastic transformation. TAMs respond to cytokines such as Interleukin (IL)-10 and Transforming Growth Factor (TGF)-β, acquiring M2 properties that promote immune suppression by blocking dendritic cell (DC) maturation and attracting regulatory T-cells (T-regs). [19,20] T-regs are potent inhibitors of the T-cell antitumor response. [21]

Activation of NF-κB pathway mediated by COX-2 and IL-6 via STAT-3 transcriptional activation also promotes malignant transformation. [22] NF-κB is a transcription factor that mediates an inflammatory cascade leading to generation of COX-2, an inducible isoform of nitric oxide synthase (iNOS) and the inflammatory cytokines IL-1β, IL-6, and Tumor Necrosis Factor (TNF) -α. These cytokines, in conjunction with nitric oxide produced by TAMs and tumor cells, are present in high concentration in the tumor microenvironment and are important promoters of inflammation-driven oncogenesis and immunosuppression. [23-25]

**Figure 1.** Pathway linking chronic inflammation and oncogenesis. (Adapted from Schetter et. al. [13])

#### **3. Concept of oncomodulation**

1. Sustaining proliferative signaling

5. Activating invasion and metastasis

6. Enabling replicative immortality

7. Tumor-promoting inflammation

Associations linking chronic infection, chronic inflammation and malignancy have been well chronicled. [13] As many as 25% of all cancers can be traced to chronic infection or other types of chronic inflammation. [14] Infectious agents that cause chronic inflammation promote oncogenesis by complex pathways, and are depicted in Figure 1. Key mediators of inflamma‐ tion-induced oncogenesis include generation of mutagenic chemical mediators such as reactive oxygen and nitrogen species, genetic variations in inflammatory cytokines [15], and creation of a micro-environment with features of chronic inflammation such as nuclear factor kappa B (NF-κB). [16,17] In such conditions, tumor-associated macrophages (TAMs) play a pivotal role in mediating inflammatory (M1) responses, as well as immunosuppressive and

M2-polarized TAMs and the related myeloid-derived suppressor cells are key components of smoldering inflammation that drives neoplastic progression. The M2 responses, while important for wound healing, can promote neoplastic transformation. TAMs respond to cytokines such as Interleukin (IL)-10 and Transforming Growth Factor (TGF)-β, acquiring M2 properties that promote immune suppression by blocking dendritic cell (DC) maturation and attracting regulatory T-cells (T-regs). [19,20] T-regs are potent inhibitors of the T-cell anti-

Activation of NF-κB pathway mediated by COX-2 and IL-6 via STAT-3 transcriptional activation also promotes malignant transformation. [22] NF-κB is a transcription factor that mediates an inflammatory cascade leading to generation of COX-2, an inducible isoform of nitric oxide synthase (iNOS) and the inflammatory cytokines IL-1β, IL-6, and Tumor Necrosis Factor (TNF) -α. These cytokines, in conjunction with nitric oxide produced by TAMs and tumor cells, are present in high concentration in the tumor microenvironment and are important promoters of inflammation-driven oncogenesis and immunosuppression. [23-25]

2. Evading growth suppressors

3. Resisting cell death

**Table 1.** The "seven" hallmarks of cancer

96 Manifestations of Cytomegalovirus Infection

growth (M2) responses. [18]

tumor response. [21]

**2. Chronic inflammation and oncogenesis**

4. Inducing angiogenesis

Tumor cells have aberrations in cell cycle signaling, RNA transcription and the production of tumor-suppression proteins. The concept of "oncomodulation" suggests that a virus may modulate cellular pathways [26] through changes to viral regulatory proteins and noncoding RNA which eludes to tumor cell properties (cell proliferation, survival, invasion, production of angiogenic factors, and immune evasion). hCMV not only promotes oncogenesis but also contributes to a more malignant tumor cell phenotype (Figure 2). While investigators have long postulated a role for hCMV in human neoplasia, many of the early studies were not reproducible and lacked clear *in situ* histopathological correlations with the proposed diseases. [27,28] The concept of "hit-and-run" oncogenesis holds that infection with hCMV takes place during an earlier time frame to tumour development. hCMV infection sets into motion processes resulting in malignancy, but the virus is no longer detectable by the time cancer occurs. [29] Several of the more important cellular pathways that could lead to cancer and which are modulated by hCMV are reviewed below.

#### **3.1. Resistance to apoptosis**

Resistance to apoptosis is a common feature of cancer cells. [9,30,31] Early research on hCMV infection revealed that hCMV protects the fibroblasts it infects from apoptosis. hCMV immediate early (IE) proteins (e.g., IE2-86 & IE2-72) [32] are able to prevent adenovirus E1A

**Figure 2.** Concept of Oncomodulation. (Adapted from Michaelis et. al. [99])

protein-induced apoptosis-by both p53-dependent and independent mechanisms- of hCMV infected fibroblasts. Direct anti-apoptotic activity of hCMV proteins is related to defined transcripts encoded by the hCMV UL36-UL37 genes. [33,34] The product of the UL36 gene is an inhibitor of caspase activation which binds to the pro-domain of caspase-8 and inhibits Fasmediated apoptosis. [35] Similarly, the UL37 gene product, UL37 exon 1, is a mitochondrial inhibitor of apoptosis and inhibits the recruitment of the pro-apoptotic proteins Bax and *Bak* to mitochondria, resulting in their functional inactivation. [36] hCMV further protects tumor cells from apoptosis by the induction of cellular proteins, including *AKT, Bcl-2, and ΔNp73α*. [37] Induction of the anti-apoptotic protein *Bcl-2* by hCMV, results in acquired resistance to cytotoxic drugs such as cisplatin and etoposide. This resistance can be reversed after treatment with the anti-hCMV drug, ganciclovir. [ 37] Engagement of platelet derived growth factor receptor (PDGFR) α or virus co-receptors (including integrins and Toll-like receptor-2) by hCMV glycoproteins can also lead to activation of mitogen-activated protein kinase (MAPK) and/or phosphatidyl-inositol 3-kinase (PI3-K) pathways that can alter apoptotic responses (Figure 3). [38-40]

increased binding to endothelium, which is an important early process in formation of

**Figure 3.** Major signaling pathways activated by hCMV that contribute to oncomodulation by hCMV. (Adapted from

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99

Angiogenesis is the growth of the new blood vessels and is essential for growth of malignant tumors. [9,46] Through the technique of secretome analysis researchers have shown that proteins secreted from hCMV-infected cells contain increased levels of pro-angiogenic molecules, and increased pro-angiogenic activity in cell-free supernatants. [47] US28 is a hCMV protein seen in high concentrations in the supernatant. This particular protein alters adhesion properties of epithelial cells inducing a pro-angiogenic and transformed phenotype through up-regulation of vascular endothelial growth factor (VEGF). [48] Additional supernatant proteins, including IE1-72 and IE2-86, increase vascular smooth muscle cell migration, proliferation, and expression of PDGF-β receptor. Furthermore, IE2-86 promotes endothelial proliferation by binding and inactivating the tumor oncogene p53 in endothelial cells. [49,50] Expression of IL-8, another well-recognized promoter of tumor angiogenesis, is increased by hCMV via transactivation of IL-8 promoter through the cellular transcription factors NF-κB and AP-1. [51] Binding of hCMV to and signaling through integrin β1, integrin β3, and

epidermal growth factor receptor can also promote angiogenesis. [47,52]

metastasis.

**3.3. Angiogenesis**

from Michaelis et. al. [100])

#### **3.2. Cancer cell adhesion, migration and invasion**

Adhesion of cancer cells to endothelium is critical in promoting metastases. [41-43] hCMV can facilitate this process by promoting activation of integrins (e.g., β1α5 and B1) on the tumor cell surface, and by increasing adhesion of tumor cells to the neighboring endothelium. Tumor cell adhesion to endothelium is also facilitated by activation of integrin-linked kinases (e.g., phosphorylation of focal adhesion kinase Tyr397). [4,,44] Down regulation of adhesion molecule receptors by hCMV (e.g., neural cell adhesion molecule, CD56), causes a focal disruption of endothelial cells facilitating tumor cell transmigration. [1,45] The net effects of hCMV on adhesion molecules account for decreased binding of cancer cells to each other and

**Figure 3.** Major signaling pathways activated by hCMV that contribute to oncomodulation by hCMV. (Adapted from from Michaelis et. al. [100])

increased binding to endothelium, which is an important early process in formation of metastasis.

#### **3.3. Angiogenesis**

protein-induced apoptosis-by both p53-dependent and independent mechanisms- of hCMV infected fibroblasts. Direct anti-apoptotic activity of hCMV proteins is related to defined transcripts encoded by the hCMV UL36-UL37 genes. [33,34] The product of the UL36 gene is an inhibitor of caspase activation which binds to the pro-domain of caspase-8 and inhibits Fasmediated apoptosis. [35] Similarly, the UL37 gene product, UL37 exon 1, is a mitochondrial inhibitor of apoptosis and inhibits the recruitment of the pro-apoptotic proteins Bax and *Bak* to mitochondria, resulting in their functional inactivation. [36] hCMV further protects tumor cells from apoptosis by the induction of cellular proteins, including *AKT, Bcl-2, and ΔNp73α*. [37] Induction of the anti-apoptotic protein *Bcl-2* by hCMV, results in acquired resistance to cytotoxic drugs such as cisplatin and etoposide. This resistance can be reversed after treatment

receptor (PDGFR) α or virus co-receptors (including integrins and Toll-like receptor-2) by hCMV glycoproteins can also lead to activation of mitogen-activated protein kinase (MAPK) and/or phosphatidyl-inositol 3-kinase (PI3-K) pathways that can alter apoptotic responses

Adhesion of cancer cells to endothelium is critical in promoting metastases. [41-43] hCMV can facilitate this process by promoting activation of integrins (e.g., β1α5 and B1) on the tumor cell surface, and by increasing adhesion of tumor cells to the neighboring endothelium. Tumor cell adhesion to endothelium is also facilitated by activation of integrin-linked kinases (e.g., phosphorylation of focal adhesion kinase Tyr397). [4,,44] Down regulation of adhesion molecule receptors by hCMV (e.g., neural cell adhesion molecule, CD56), causes a focal disruption of endothelial cells facilitating tumor cell transmigration. [1,45] The net effects of hCMV on adhesion molecules account for decreased binding of cancer cells to each other and

37] Engagement of platelet derived growth factor

with the anti-hCMV drug, ganciclovir. [

98 Manifestations of Cytomegalovirus Infection

**3.2. Cancer cell adhesion, migration and invasion**

**Figure 2.** Concept of Oncomodulation. (Adapted from Michaelis et. al. [99])

(Figure 3). [38-40]

Angiogenesis is the growth of the new blood vessels and is essential for growth of malignant tumors. [9,46] Through the technique of secretome analysis researchers have shown that proteins secreted from hCMV-infected cells contain increased levels of pro-angiogenic molecules, and increased pro-angiogenic activity in cell-free supernatants. [47] US28 is a hCMV protein seen in high concentrations in the supernatant. This particular protein alters adhesion properties of epithelial cells inducing a pro-angiogenic and transformed phenotype through up-regulation of vascular endothelial growth factor (VEGF). [48] Additional supernatant proteins, including IE1-72 and IE2-86, increase vascular smooth muscle cell migration, proliferation, and expression of PDGF-β receptor. Furthermore, IE2-86 promotes endothelial proliferation by binding and inactivating the tumor oncogene p53 in endothelial cells. [49,50] Expression of IL-8, another well-recognized promoter of tumor angiogenesis, is increased by hCMV via transactivation of IL-8 promoter through the cellular transcription factors NF-κB and AP-1. [51] Binding of hCMV to and signaling through integrin β1, integrin β3, and epidermal growth factor receptor can also promote angiogenesis. [47,52]

Expression of thrombospondin (TSP-1), a potent inhibitor of angiogenesis, is suppressed in several hCMV-infected cancer cell lines, suggesting yet another mechanism by which hCMV can promote increased angiogenesis and a more malignant phenotype. [53,54] hCMV mediated activation of COX-2 may also promote angiogenesis in tumor cells by inducing expression of Fibroblast Growth Factor (FGF), VEGF, PDGF, iNOS, and TGF-α, and by promoting capillary endothelial cell migration and tube formation (Figure 3). [55]

disrupts "natural killer" (NK) cell recognition of hCMV-infected cells. [75] Disruption of hCMV antigen presentation by infected cells is mediated by hCMV protein US3, which sequesters MHC class I complexes in the endoplasmic reticulum, and hCMV protein US11 which causes dislocation of the MHC class I heavy chain from the cytoplasm. [76-78] hCMVencoded IL-10 homologue impairs tumor antigen presentation by inhibiting maturation, normal differentiation and cytokine production of dendritic cells and macrophages.. [79-81] hCMV induces integrin αvβ6 expression in endothelial cells of blood vessels in different tissues, causing activation of TGF-β1, resulting in interference of host immune responses against tumor cells by blocking the activation of lymphocytes and monocyte derived phagocytes. [82] These direct immune-modulatory effects of hCMV on myeloid cells within the tumor microenvir‐ onment, along with expression of immunosuppressive cytokines provide a virtually impass‐

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Persistent hCMV infection of non-neoplastic cells in the tumor microenvironment leads to a paracrine secretion of inflammatory molecules that promote malignancy. [83] The secretome of hCMV-infected fibroblasts contains exceedingly high levels of growth factors, matrix remodeling proteins such as matrix metalloproteinases (MMPs), and angiogenic factors that signal through the TGF-β pathway. [47,84] These paracrine-secreted factors are also able to activate latent growth factors. PDGFs acts as strong mitogens and their overexpression is important in the pathogenesis of multiple malignancies. [85-87] In addition to growth factors, high levels of many ECM modifiers such as MMPs, tissue inhibitors of metalloproteinases (TIMPs) and urokinase receptor (uPAR) secreted by hCMV infected cells aiding, tumor

**6. DNA mutations, impaired DNA repair mechanisms and epigenetic**

hCMV infection can drive neoplastic transformation by causing chromosome damage and genetic instability in infected cells, particularly in vulnerable adult stem cells. [88-90] hCMV in combination with cytotoxic chemotherapy agents synergistically increases genotoxic effects. [91,92] The virus can induce specific chromosome 1 strand breaks at positions 1q42 and 1q21 in a replication-independent fashion, both of which are associated with DNA repair and replication genes. [89,93,94] hCMV IE1-72 and IE2-86 proteins when in conjunction with other viral oncogenic proteins (e.g., adenovirus E1A protein) that disrupt cell cycle can induce

hCMV can contribute to genomic instability through a variety of different pathways. In brief, the virus may induce chromosomal aberrations (e.g., production of micronuclei, misaligned chromosomes, chromosomal lagging and bridging) by hCMV UL76 protein. [95,96] The virus

able environment for the host anti-tumor immune system.

invasion and metastasis. [84]

oncogenic transformation. [29]

**5. Influence of CMV on tumor microenvironment**

**changes by hCMV that leads to genomic instability**

#### **3.4. Impact of hCMV on cell cycle**

In hCMV-infected host cells, viral regulatory proteins induce cell cycle arrest and prevent cellular DNA replication, whilst replication of viral DNA remains enabled. [8,56] While some hCMV regulatory proteins can induce cell cycle arrest, others can promote cell cycle progres‐ sion. [57,58] hCMV IE2-86 induces cell cycle arrest by activating ataxia telangiectasia mutated (ATM) gene-dependent phosphorylation of p53, leading to p53- and p21-dependent inhibition of cell cycle progression. [59] In contrast, the hCMV regulatory proteins IE1-72, IE2-86, and the tegument proteins *pp*71 and UL97 interact with and deactivate proteins of the Rb family, promoting entry into S-phase of the cell cycle. [60]

The cell cycle of neoplastic cells is inherently dysfunctional. [9,31] In precancerous or trans‐ formed cells, the function of virus regulatory proteins may depend on the replicative status of the cell. [61,62] The hCMV protein US28 promotes cell cycle progression and cyclin D1 expression in cells with a neoplastic phenotype; whereas, it induces apoptosis in non-neo‐ plastic cells. [48] Persistent hCMV infection of tumor cells may lead to a selection of virus variants with changes in virus regulatory proteins that have lost their ability to induce cell cycle arrest. [63,64]

#### **4. Escape of immune surveillance by cancer cells: Role of hCMV**

Immunological tolerance is a process by which the immune system no longer recognizes an aberrant antigen as "foreign." [67] Through "natural" or "self-tolerance" the body does not mount an immune response to self-antigens. "Induced tolerance" to external antigens can be created by manipulating the immune system. Mechanisms of tolerance that exist to prevent autoimmune disease may also preclude the development of an adequate antitumor response. [65-67] This concept of "immune tolerance" may be particularly important in malignancies whose etiology is associated with inflammation. [68] Expression of hCMV proteins by infected tumor cells may induce 'immune tolerance' to tumor cells. Also, several tumor-derived factors contribute to the emergence of complex local and regional immunosuppressive networks, including VEGF, IL-10, TGF-β, and prostaglandin E-2 (PGE2). [66,69]

hCMV has evolved multiple strategies for immune evasion resulting in persistent viral infection in the host [70-74] Several hCMV proteins, including those expressed with IE genes, block the host cell MHC class I antigen expression, which is essential for activation of CD8+ T-lymphocyte anti-tumor cytotoxicity. hCMV UL83 protein (pp65) blocks antigen presentation of hCMV epitopes to CD8+ T-cells, and expression of hCMV UL18, a MHC class I homologue, disrupts "natural killer" (NK) cell recognition of hCMV-infected cells. [75] Disruption of hCMV antigen presentation by infected cells is mediated by hCMV protein US3, which sequesters MHC class I complexes in the endoplasmic reticulum, and hCMV protein US11 which causes dislocation of the MHC class I heavy chain from the cytoplasm. [76-78] hCMVencoded IL-10 homologue impairs tumor antigen presentation by inhibiting maturation, normal differentiation and cytokine production of dendritic cells and macrophages.. [79-81] hCMV induces integrin αvβ6 expression in endothelial cells of blood vessels in different tissues, causing activation of TGF-β1, resulting in interference of host immune responses against tumor cells by blocking the activation of lymphocytes and monocyte derived phagocytes. [82] These direct immune-modulatory effects of hCMV on myeloid cells within the tumor microenvir‐ onment, along with expression of immunosuppressive cytokines provide a virtually impass‐ able environment for the host anti-tumor immune system.

#### **5. Influence of CMV on tumor microenvironment**

Expression of thrombospondin (TSP-1), a potent inhibitor of angiogenesis, is suppressed in several hCMV-infected cancer cell lines, suggesting yet another mechanism by which hCMV can promote increased angiogenesis and a more malignant phenotype. [53,54] hCMV mediated activation of COX-2 may also promote angiogenesis in tumor cells by inducing expression of Fibroblast Growth Factor (FGF), VEGF, PDGF, iNOS, and TGF-α, and by

In hCMV-infected host cells, viral regulatory proteins induce cell cycle arrest and prevent cellular DNA replication, whilst replication of viral DNA remains enabled. [8,56] While some hCMV regulatory proteins can induce cell cycle arrest, others can promote cell cycle progres‐ sion. [57,58] hCMV IE2-86 induces cell cycle arrest by activating ataxia telangiectasia mutated (ATM) gene-dependent phosphorylation of p53, leading to p53- and p21-dependent inhibition of cell cycle progression. [59] In contrast, the hCMV regulatory proteins IE1-72, IE2-86, and the tegument proteins *pp*71 and UL97 interact with and deactivate proteins of the Rb family,

The cell cycle of neoplastic cells is inherently dysfunctional. [9,31] In precancerous or trans‐ formed cells, the function of virus regulatory proteins may depend on the replicative status of the cell. [61,62] The hCMV protein US28 promotes cell cycle progression and cyclin D1 expression in cells with a neoplastic phenotype; whereas, it induces apoptosis in non-neo‐ plastic cells. [48] Persistent hCMV infection of tumor cells may lead to a selection of virus variants with changes in virus regulatory proteins that have lost their ability to induce cell

Immunological tolerance is a process by which the immune system no longer recognizes an aberrant antigen as "foreign." [67] Through "natural" or "self-tolerance" the body does not mount an immune response to self-antigens. "Induced tolerance" to external antigens can be created by manipulating the immune system. Mechanisms of tolerance that exist to prevent autoimmune disease may also preclude the development of an adequate antitumor response. [65-67] This concept of "immune tolerance" may be particularly important in malignancies whose etiology is associated with inflammation. [68] Expression of hCMV proteins by infected tumor cells may induce 'immune tolerance' to tumor cells. Also, several tumor-derived factors contribute to the emergence of complex local and regional immunosuppressive networks,

hCMV has evolved multiple strategies for immune evasion resulting in persistent viral infection in the host [70-74] Several hCMV proteins, including those expressed with IE genes, block the host cell MHC class I antigen expression, which is essential for activation of CD8+ T-lymphocyte anti-tumor cytotoxicity. hCMV UL83 protein (pp65) blocks antigen presentation of hCMV epitopes to CD8+ T-cells, and expression of hCMV UL18, a MHC class I homologue,

**4. Escape of immune surveillance by cancer cells: Role of hCMV**

including VEGF, IL-10, TGF-β, and prostaglandin E-2 (PGE2). [66,69]

promoting capillary endothelial cell migration and tube formation (Figure 3). [55]

**3.4. Impact of hCMV on cell cycle**

100 Manifestations of Cytomegalovirus Infection

cycle arrest. [63,64]

promoting entry into S-phase of the cell cycle. [60]

Persistent hCMV infection of non-neoplastic cells in the tumor microenvironment leads to a paracrine secretion of inflammatory molecules that promote malignancy. [83] The secretome of hCMV-infected fibroblasts contains exceedingly high levels of growth factors, matrix remodeling proteins such as matrix metalloproteinases (MMPs), and angiogenic factors that signal through the TGF-β pathway. [47,84] These paracrine-secreted factors are also able to activate latent growth factors. PDGFs acts as strong mitogens and their overexpression is important in the pathogenesis of multiple malignancies. [85-87] In addition to growth factors, high levels of many ECM modifiers such as MMPs, tissue inhibitors of metalloproteinases (TIMPs) and urokinase receptor (uPAR) secreted by hCMV infected cells aiding, tumor invasion and metastasis. [84]

#### **6. DNA mutations, impaired DNA repair mechanisms and epigenetic changes by hCMV that leads to genomic instability**

hCMV infection can drive neoplastic transformation by causing chromosome damage and genetic instability in infected cells, particularly in vulnerable adult stem cells. [88-90] hCMV in combination with cytotoxic chemotherapy agents synergistically increases genotoxic effects. [91,92] The virus can induce specific chromosome 1 strand breaks at positions 1q42 and 1q21 in a replication-independent fashion, both of which are associated with DNA repair and replication genes. [89,93,94] hCMV IE1-72 and IE2-86 proteins when in conjunction with other viral oncogenic proteins (e.g., adenovirus E1A protein) that disrupt cell cycle can induce oncogenic transformation. [29]

hCMV can contribute to genomic instability through a variety of different pathways. In brief, the virus may induce chromosomal aberrations (e.g., production of micronuclei, misaligned chromosomes, chromosomal lagging and bridging) by hCMV UL76 protein. [95,96] The virus can also disrupt DNA repair pathways, including the activity of ATM and ATM-Rad3 (ATR). [97] More recently, hCMV has been shown to modulate oncogenesis through the telomerase pathway by activating human telomerase reverse transcriptase (hTERT) in fibroblasts and malignant cells. [98]

[2] Harkins LE, Matlaf LA, Soroceanu L, et al. Detection of human cytomegalovirus in

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2373-2380.

#### **7. Conclusions**

Significant advances have been made in understanding the roles of chronic inflammation, tumor microenvironment, cancer stem cells, tumor immunology, and infectious agents in the pathobiology of cancer. Several clinical and experimental findings suggest that hCMV may play a role in promoting certain cancers. In cells that are persistently infected with hCMV, the expression of viral proteins may prevent the immune system from identifying or removing these cells, thereby offsetting immune detection of transformed cells. The effects of hCMV in promoting tumor cell immune evasion may prove important in development of cancer immunotherapies, particularly if the hCMV-infected cells are resistant to the action of cytolytic peptides released by activated NK and cytotoxic T-cells. Also, if viral proteins that inhibit apoptosis are expressed by hCMV infected tumour cells, the cancer cells may be less suscep‐ tible conventional chemotherapeutic agents. Whether hCMV is ultimately established as an oncogenic virus will require additional research in the areas of virology, epidemiology and molecular oncology, and systematic refinement of the concept of "oncomodulation." Insights into the role of hCMV in oncogenesis may increase understanding of cancer biology and promote development of novel therapeutic strategies.

#### **Author details**

Prakash Vishnu1 and David M. Aboulafia1,2\*

\*Address all correspondence to: david.aboulafia@vmmc.org

1 Floyd & Delores Jones Cancer Institute at Virginia Mason Medical Center, Seattle, WA, USA

2 Division of Hematology, University of Washington, Seattle, WA, USA

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Significant advances have been made in understanding the roles of chronic inflammation, tumor microenvironment, cancer stem cells, tumor immunology, and infectious agents in the pathobiology of cancer. Several clinical and experimental findings suggest that hCMV may play a role in promoting certain cancers. In cells that are persistently infected with hCMV, the expression of viral proteins may prevent the immune system from identifying or removing these cells, thereby offsetting immune detection of transformed cells. The effects of hCMV in promoting tumor cell immune evasion may prove important in development of cancer immunotherapies, particularly if the hCMV-infected cells are resistant to the action of cytolytic peptides released by activated NK and cytotoxic T-cells. Also, if viral proteins that inhibit apoptosis are expressed by hCMV infected tumour cells, the cancer cells may be less suscep‐ tible conventional chemotherapeutic agents. Whether hCMV is ultimately established as an oncogenic virus will require additional research in the areas of virology, epidemiology and molecular oncology, and systematic refinement of the concept of "oncomodulation." Insights into the role of hCMV in oncogenesis may increase understanding of cancer biology and

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Prakash Vishnu1

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[77] Benz C, Hengel H. MHC class I-subversive gene functions of cytomegalovirus and their regulation by interferons-an intricate balance. *Virus genes.* 2000;21(1-2):39-47. [78] Besold K, Wills M, Plachter B. Immune evasion proteins gpUS2 and gpUS11 of hu‐ man cytomegalovirus incompletely protect infected cells from CD8 T cell recogni‐

[79] Chang WL, Baumgarth N, Yu D, Barry PA. Human cytomegalovirus-encoded inter‐ leukin-10 homolog inhibits maturation of dendritic cells and alters their functionali‐

plant recipients. *The Journal of infectious diseases.* Aug 1 2001;184(3):247-255.

2006;119(2):254-264.

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190-197.

41-49.

213-216.

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tion. *Virology.* Aug 15 2009;391(1):5-19.

ty. *Journal of virology.* Aug 2004;78(16):8720-8731.

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**Chapter 7**

**Cytomegalovirus Tegument Proteins and the**

**Development of Novel Antiviral Therapeutics**

Cytomegalovirus (CMV) is a widespread pathogen that infects a majority of the world's population by early adulthood with approximately 50-85% of individuals over 40 being seropositive [1,2]. CMV can establish a life-long infection with its host by becoming latent during the lysogenic stage of the viral life cycle in which the virus becomes dormant and the shedding and production of infectious virions ceases [3]. However, the virus can later re-enter the lytic stage of the viral life cycle when presented with certain environmental cues, such as stress, thereby triggering the production of viral progeny and resulting in an acute infection of the host. Immunocompetent individuals generally display no symptoms of acute CMV infection, but CMV can cause morbidity and mortality in those with weakened or not fully developed immune systems [4]. The clinical manifestations of CMV infections in those with weakened immune systems, include spiking fever, malaise, leucopenia, encephalitis, pneu‐ monitis, hepatitis, uveitis, retinitis, gastrointestinal disease and graft rejection [5,6]. If primary infection or reactivation of CMV occurs during pregnancy in women, serious complications will arise for the fetus or developing embryo. CMV is the leading cause of viral birth defects, including microcephaly, mental retardation, spastic paralysis, hepatosplenomegaly, anemia, thrombocytopenia, deafness, and optic nerve atrophy that subsequently leads to blindness [5,

Although immunocompetent individuals generally display no symptoms of CMV infection, CMV has been implicated in playing a role in several proliferative and inflammatory diseases [9]. CMV has been linked with several forms of cancer, such as colon, breast, and prostate. Previously, CMV was regarded as having an oncomodulatory role in cancers by infecting tumor cells and modulating their malignant properties. It was hypothesized that tumor cells provided a genetic environment that allowed CMV to exert its oncomodulatory effects. CMV

> © 2013 Tomtishen; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

> © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

distribution, and reproduction in any medium, provided the original work is properly cited.

and reproduction in any medium, provided the original work is properly cited.

7]. CMV is also responsible for 8% of infectious mononucleosis cases [8].

John Paul III Tomtishen

http://dx.doi.org/10.5772/55156

**1. Introduction**

Additional information is available at the end of the chapter


### **Cytomegalovirus Tegument Proteins and the Development of Novel Antiviral Therapeutics**

John Paul III Tomtishen

[93] Fortunato EA, Dell'Aquila ML, Spector DH. Specific chromosome 1 breaks induced by human cytomegalovirus. *Proceedings of the National Academy of Sciences of the Unit‐*

[94] Baumgartner M, Schneider R, Auer B, Herzog H, Schweiger M, Hirsch-Kauffmann M. Fluorescence in situ mapping of the human nuclear NAD+ ADP-ribosyltransfer‐ ase gene (ADPRT) and two secondary sites to human chromosomal bands 1q42,

[95] Albrecht T, Deng CZ, Abdel-Rahman SZ, Fons M, Cinciripini P, El-Zein RA. Differ‐ ential mutagen sensitivity of peripheral blood lymphocytes from smokers and non‐ smokers: effect of human cytomegalovirus infection. *Environmental and molecular*

[96] Siew VK, Duh CY, Wang SK. Human cytomegalovirus UL76 induces chromosome

[97] Luo MH, Rosenke K, Czornak K, Fortunato EA. Human cytomegalovirus disrupts both ataxia telangiectasia mutated protein (ATM)- and ATM-Rad3-related kinasemediated DNA damage responses during lytic infection. *Journal of virology.* Feb

[98] Straat K, Liu C, Rahbar A, et al. Activation of telomerase by human cytomegalovirus.

[99] Michaelis M, Baumgarten P, Mittelbronn M, Driever PH, Doerr HW, Cinatl J, Jr. On‐ comodulation by human cytomegalovirus: novel clinical findings open new roads.

[100] Michaelis M, Doerr HW, Cinatl J. The story of human cytomegalovirus and cancer:

increasing evidence and open questions. *Neoplasia.* Jan 2009;11(1):1-9.

*Journal of the National Cancer Institute.* Apr 1 2009;101(7):488-497.

*Medical microbiology and immunology.* Feb 2011;200(1):1-5.

13q34, and 14q24. *Cytogenetics and cell genetics.* 1992;61(3):172-174.

*ed States of America.* Jan 18 2000;97(2):853-858.

aberrations. *Journal of biomedical science.* 2009;16:107.

*mutagenesis.* 2004;43(3):169-178.

2007;81(4):1934-1950.

110 Manifestations of Cytomegalovirus Infection

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/55156

#### **1. Introduction**

Cytomegalovirus (CMV) is a widespread pathogen that infects a majority of the world's population by early adulthood with approximately 50-85% of individuals over 40 being seropositive [1,2]. CMV can establish a life-long infection with its host by becoming latent during the lysogenic stage of the viral life cycle in which the virus becomes dormant and the shedding and production of infectious virions ceases [3]. However, the virus can later re-enter the lytic stage of the viral life cycle when presented with certain environmental cues, such as stress, thereby triggering the production of viral progeny and resulting in an acute infection of the host. Immunocompetent individuals generally display no symptoms of acute CMV infection, but CMV can cause morbidity and mortality in those with weakened or not fully developed immune systems [4]. The clinical manifestations of CMV infections in those with weakened immune systems, include spiking fever, malaise, leucopenia, encephalitis, pneu‐ monitis, hepatitis, uveitis, retinitis, gastrointestinal disease and graft rejection [5,6]. If primary infection or reactivation of CMV occurs during pregnancy in women, serious complications will arise for the fetus or developing embryo. CMV is the leading cause of viral birth defects, including microcephaly, mental retardation, spastic paralysis, hepatosplenomegaly, anemia, thrombocytopenia, deafness, and optic nerve atrophy that subsequently leads to blindness [5, 7]. CMV is also responsible for 8% of infectious mononucleosis cases [8].

Although immunocompetent individuals generally display no symptoms of CMV infection, CMV has been implicated in playing a role in several proliferative and inflammatory diseases [9]. CMV has been linked with several forms of cancer, such as colon, breast, and prostate. Previously, CMV was regarded as having an oncomodulatory role in cancers by infecting tumor cells and modulating their malignant properties. It was hypothesized that tumor cells provided a genetic environment that allowed CMV to exert its oncomodulatory effects. CMV

© 2013 Tomtishen; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

was then identified as a potential therapeutic target in those tumors infected with CMV [10-12]. However, recent evidence supports oncogenic properties of CMV in certain cancers, such those as in salivary gland [13]. Furthermore, epidemiological and pathological studies suggest a strong link between CMV and atherosclerosis [9]. A potential mechanism for CMV in the pathogenesis of atherosclerosis involves the reactivation of virus followed by virus-induced enhancement of vascular inflammation and damage through smooth cell proliferation, uptake of low-density lipoproteins, and narrowing of the vessel lumen [1].

Antiviral agents that inhibit CMV viral replication exist, including ganciclovir, valganciclovir (the prodrug of ganciclovir), foscarnet, and cidofovir [1]. The primary mechanism of action of ganciclovir/valganciclovir against CMV is through the inhibition of the replication of viral DNA by ganciclovir-5′-triphosphate, which includes a selective and potent inhibition of the viral DNA polymerase [14]. Foscarnet, by comparison, interferes with the exchange of pyrophosphate from deoxynucleoside triphosphate during viral replication by binding to a site on the CMV DNA polymerase [15]. Similarly, cidofovir inhibits CMV DNA synthesis by DNA chain termination following incorporation of two consecutive cidofovir molecules at the 3'-end of the DNA chain [16]. Nonetheless, the antiviral agents commonly used to treat CMV infections suffer from high hematologic, renal, and neutropenia toxicity, low bioavailability and the development of drug-resistant virus strains [9,17]. Furthermore, there is no effective vaccine available.

The lack of an effective treatment for CMV infections has increased interest in the identification of targets for the development of novel CMV antiviral treatments. These include proteins found within the tegument of CMV virions. These proteins are abundant and play pivotal roles in the viral life cycle, including immune evasion, viral entry, gene expression, assembly of new virus particles and egress through an envelopment-deenvelopment-reenvelopment process [18]. The structure of the CMV tegument, the roles of some major tegument proteins in the CMV life cycle, and the therapeutic potential of CMV tegument proteins will be reviewed.

proteins to the protein capsid [20]. The tegument proteins comprise more than half of the total proteins found within infectious CMV virions [21]. Tegument proteins are phosphorylated and undergo other posttranslational modifications, but the significance of these modifications is unknown [19]. A common biochemical sequence to direct proteins into the tegument has not been identified, and the process of assembling the viral tegument upon viral egress and disassembly upon viral entry into cells is unclear [22]. Incorporation of proteins in the tegument is likely facilitated by the phosphorylation of the tegument proteins, their subcellular localization to the assembly site and their interaction with capsids or the cytoplasmic tails of

**Figure 1.** A cartoon depicting the structure of the HCMV virion. (Image obtained from (http://www.virology.net/

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113

big\_virology/bvdnaherpes.html website) courtesy of Dr. Marko Reschke in Marburg, Germany).

As mentioned, the tegument proteins gain entry into the host cell along with the DNAcontaining protein nucleocapsid upon fusion of the outer membrane of the host cell and the outer glycoprotein riddled lipid membrane of the CMV virion [19]. Once the tegument proteins are released into the cytoplasm, they become functionally active and participate in all stages

The CMV tegument proteins play pivotal roles illustrated in Figure 2. The known or inferred functions of tegument proteins are presented in Table 1, compiled using a functional profiling of the CMV genome from a global mutational analysis [18,62,63]. Gene expression classifica‐ tions are based on when expression occurs during the viral life cycle (Immediate-Early, Early, Early-Late, and Late). Finally, the tegument proteins are categorized based on their role in lytic

envelope proteins [18].

of the viral life cycle [1].

**3. Cytomegalovirus tegument proteins**

#### **2. Cytomegalovirus structure and function of the tegument**

CMV is a member of the *Betaherpesvirinae* sub-family of the *Herpesviridae* family, (Figure 1). The virion has an icosahedral protein nucleocapsid that contains the 235-kb doublestranded DNA. The capsid is surrounded by a proteinaceous tegument and an outer lipid envelope [1]. CMV virions gain entry into a host cell via a membrane fusion event involving the outer membrane of the cell and the glycoproteins located on the lipid envelope of the virion. When the cell membrane and lipid envelope fuse, the DNA-containing protein nucleocapsid and tegument proteins are released into the host cell. This initiates the lytic stage of the viral life cycle [19].

The proteins in the tegument are excellent candidates for novel CMV antiviral treatments due to their abundance and significant roles in all stages of the viral life cycle. The tegument, located between the outer lipid membrane and the icosahedral protein nucleocapsid is largely unstructured and amorphous although some structuring is seen with the binding of tegument

**Figure 1.** A cartoon depicting the structure of the HCMV virion. (Image obtained from (http://www.virology.net/ big\_virology/bvdnaherpes.html website) courtesy of Dr. Marko Reschke in Marburg, Germany).

proteins to the protein capsid [20]. The tegument proteins comprise more than half of the total proteins found within infectious CMV virions [21]. Tegument proteins are phosphorylated and undergo other posttranslational modifications, but the significance of these modifications is unknown [19]. A common biochemical sequence to direct proteins into the tegument has not been identified, and the process of assembling the viral tegument upon viral egress and disassembly upon viral entry into cells is unclear [22]. Incorporation of proteins in the tegument is likely facilitated by the phosphorylation of the tegument proteins, their subcellular localization to the assembly site and their interaction with capsids or the cytoplasmic tails of envelope proteins [18].

As mentioned, the tegument proteins gain entry into the host cell along with the DNAcontaining protein nucleocapsid upon fusion of the outer membrane of the host cell and the outer glycoprotein riddled lipid membrane of the CMV virion [19]. Once the tegument proteins are released into the cytoplasm, they become functionally active and participate in all stages of the viral life cycle [1].

#### **3. Cytomegalovirus tegument proteins**

was then identified as a potential therapeutic target in those tumors infected with CMV [10-12]. However, recent evidence supports oncogenic properties of CMV in certain cancers, such those as in salivary gland [13]. Furthermore, epidemiological and pathological studies suggest a strong link between CMV and atherosclerosis [9]. A potential mechanism for CMV in the pathogenesis of atherosclerosis involves the reactivation of virus followed by virus-induced enhancement of vascular inflammation and damage through smooth cell proliferation, uptake

Antiviral agents that inhibit CMV viral replication exist, including ganciclovir, valganciclovir (the prodrug of ganciclovir), foscarnet, and cidofovir [1]. The primary mechanism of action of ganciclovir/valganciclovir against CMV is through the inhibition of the replication of viral DNA by ganciclovir-5′-triphosphate, which includes a selective and potent inhibition of the viral DNA polymerase [14]. Foscarnet, by comparison, interferes with the exchange of pyrophosphate from deoxynucleoside triphosphate during viral replication by binding to a site on the CMV DNA polymerase [15]. Similarly, cidofovir inhibits CMV DNA synthesis by DNA chain termination following incorporation of two consecutive cidofovir molecules at the 3'-end of the DNA chain [16]. Nonetheless, the antiviral agents commonly used to treat CMV infections suffer from high hematologic, renal, and neutropenia toxicity, low bioavailability and the development of drug-resistant virus strains [9,17]. Furthermore, there is no effective

The lack of an effective treatment for CMV infections has increased interest in the identification of targets for the development of novel CMV antiviral treatments. These include proteins found within the tegument of CMV virions. These proteins are abundant and play pivotal roles in the viral life cycle, including immune evasion, viral entry, gene expression, assembly of new virus particles and egress through an envelopment-deenvelopment-reenvelopment process [18]. The structure of the CMV tegument, the roles of some major tegument proteins in the CMV life cycle, and the therapeutic potential of CMV tegument proteins will be reviewed.

CMV is a member of the *Betaherpesvirinae* sub-family of the *Herpesviridae* family, (Figure 1). The virion has an icosahedral protein nucleocapsid that contains the 235-kb doublestranded DNA. The capsid is surrounded by a proteinaceous tegument and an outer lipid envelope [1]. CMV virions gain entry into a host cell via a membrane fusion event involving the outer membrane of the cell and the glycoproteins located on the lipid envelope of the virion. When the cell membrane and lipid envelope fuse, the DNA-containing protein nucleocapsid and tegument proteins are released into the host cell. This initiates the lytic

The proteins in the tegument are excellent candidates for novel CMV antiviral treatments due to their abundance and significant roles in all stages of the viral life cycle. The tegument, located between the outer lipid membrane and the icosahedral protein nucleocapsid is largely unstructured and amorphous although some structuring is seen with the binding of tegument

**2. Cytomegalovirus structure and function of the tegument**

of low-density lipoproteins, and narrowing of the vessel lumen [1].

vaccine available.

112 Manifestations of Cytomegalovirus Infection

stage of the viral life cycle [19].

The CMV tegument proteins play pivotal roles illustrated in Figure 2. The known or inferred functions of tegument proteins are presented in Table 1, compiled using a functional profiling of the CMV genome from a global mutational analysis [18,62,63]. Gene expression classifica‐ tions are based on when expression occurs during the viral life cycle (Immediate-Early, Early, Early-Late, and Late). Finally, the tegument proteins are categorized based on their role in lytic replication. Some proteins are essential for replication, while others are required for efficient replication (augmentative), or dispensable for lytic replication. The roles of major tegument proteins are presented in sections 3.1-3.4 in the context of the various stages of the CMV life cycle, which includes viral entry, viral replication and gene expression, immune evasion of the host, and assembly and egress of new infectious virions.

proteins, facilitate the delivery of the CMV nucleocapsids to the nuclear pore complex and the release of the CMV genome into the nucleus [18,64]. Pp150 may also play a role in viral entry

Cytomegalovirus Tegument Proteins and the Development of Novel Antiviral Therapeutics

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115

Once the viral genome enters the nucleus of the host cell, the viral immediate-early genes are expressed through their activation by the pp71 tegument protein, which initiates the lytic stage of the viral life cycle and the subsequent replication of the 235-kb double-stranded CMV DNA genome [46]. It is important to note though that the expression of the immediate-early genes can be repressed resulting in a latent infection that is characterized by the minimization of viral gene expression and the inhibition of the assembly and egress of new viral progeny [1,66]. Although pp71 is known to play a pivotal role in the expression of the immediate-early genes during the lytic stage of the CMV life cycle, the gene products of UL35 and UL69 have been implicated in gene expression [18]. However, more research is necessary to identify the other

CMV evades the host cell immune system through the targeting of intrinsic, innate, and adaptive immune responses by several different tegument proteins, including pp65, pp71, and IRS1/TRS1. pp65 the major tegument protein involved in immune evasion of the host as well as IRS1/TRS1 modulate the innate and adaptive immune responses. pp71 modulates the intrinsic immune defense through its neutralization of the Daxx-mediated repression of immediate-early gene expression. Without immune evasion, the lytic stage of the viral life cycle is inhibited. The roles of pp65 and pp71 in modulating the host cell immune response is further

After viral DNA replication, the immediate-early gene products, which include several tegument proteins as seen in Table 1, turn on the expression of viral late genes [1]. The viral late proteins are mainly structural components that assist in the assembly and egress of newly formed infectious CMV virions [1]. The primary tegument proteins involved in assembly and egress are pp150, pp28, and UL97. pp150 directs the movement of the cytoplasmic capsids to the site for particle formation, while pp28 directs the enclosure of the tegument proteins and DNA-containing nucleocapsids within an enveloped particle [18,26,52]. UL97 phosphorylates the tegument proteins through its kinase activity, which may facilitate the incorporation of the tegument proteins into new infectious virions [18,30]. Once the virions are packaged, they are shed from the host cell through an exocytosis mechanism which uses the host cell's transport system to enclose vacuoles containing the newly synthesized infectious virions for release into

due to its tight association with the CMV capsids [65].

tegument proteins involved in viral gene expression.

discussed below in sections 4.1 and 4.3 respectively [18].

**3.3. Immune evasion**

**3.4. Assembly and egress**

the extracellular space.

**3.2. Viral replication and gene expression**

**Figure 2.** Illustration of the CMV life cycle from viral entry to egress of new infectious virions.

#### **3.1. Viral entry**

Mechanistically, the CMV virions enter host cells through a membrane fusion event involving the host cell's outer membrane and the glycoproteins located on the lipid envelope of the CMV virions [19]. The receptors on the viral envelope connect to complementary receptors on the cell membrane of the host cell. This initial interaction makes the cell susceptible to further interactions that allow the membranes to fuse, and the subsequent disassembly and release of the viral genomic DNA and tegument into the host cell. It is believed that several tegument proteins mediate delivery of the DNA-containing nucleocapsid to the nuclear pore complex and the release of the viral DNA into the nucleus [18]. Comparisons with other herpesviruses suggest that the UL47 and UL48 CMV tegument proteins, along with microtubule motor proteins, facilitate the delivery of the CMV nucleocapsids to the nuclear pore complex and the release of the CMV genome into the nucleus [18,64]. Pp150 may also play a role in viral entry due to its tight association with the CMV capsids [65].

#### **3.2. Viral replication and gene expression**

Once the viral genome enters the nucleus of the host cell, the viral immediate-early genes are expressed through their activation by the pp71 tegument protein, which initiates the lytic stage of the viral life cycle and the subsequent replication of the 235-kb double-stranded CMV DNA genome [46]. It is important to note though that the expression of the immediate-early genes can be repressed resulting in a latent infection that is characterized by the minimization of viral gene expression and the inhibition of the assembly and egress of new viral progeny [1,66]. Although pp71 is known to play a pivotal role in the expression of the immediate-early genes during the lytic stage of the CMV life cycle, the gene products of UL35 and UL69 have been implicated in gene expression [18]. However, more research is necessary to identify the other tegument proteins involved in viral gene expression.

#### **3.3. Immune evasion**

replication. Some proteins are essential for replication, while others are required for efficient replication (augmentative), or dispensable for lytic replication. The roles of major tegument proteins are presented in sections 3.1-3.4 in the context of the various stages of the CMV life cycle, which includes viral entry, viral replication and gene expression, immune evasion of the

host, and assembly and egress of new infectious virions.

114 Manifestations of Cytomegalovirus Infection

**Figure 2.** Illustration of the CMV life cycle from viral entry to egress of new infectious virions.

Mechanistically, the CMV virions enter host cells through a membrane fusion event involving the host cell's outer membrane and the glycoproteins located on the lipid envelope of the CMV virions [19]. The receptors on the viral envelope connect to complementary receptors on the cell membrane of the host cell. This initial interaction makes the cell susceptible to further interactions that allow the membranes to fuse, and the subsequent disassembly and release of the viral genomic DNA and tegument into the host cell. It is believed that several tegument proteins mediate delivery of the DNA-containing nucleocapsid to the nuclear pore complex and the release of the viral DNA into the nucleus [18]. Comparisons with other herpesviruses suggest that the UL47 and UL48 CMV tegument proteins, along with microtubule motor

**3.1. Viral entry**

CMV evades the host cell immune system through the targeting of intrinsic, innate, and adaptive immune responses by several different tegument proteins, including pp65, pp71, and IRS1/TRS1. pp65 the major tegument protein involved in immune evasion of the host as well as IRS1/TRS1 modulate the innate and adaptive immune responses. pp71 modulates the intrinsic immune defense through its neutralization of the Daxx-mediated repression of immediate-early gene expression. Without immune evasion, the lytic stage of the viral life cycle is inhibited. The roles of pp65 and pp71 in modulating the host cell immune response is further discussed below in sections 4.1 and 4.3 respectively [18].

#### **3.4. Assembly and egress**

After viral DNA replication, the immediate-early gene products, which include several tegument proteins as seen in Table 1, turn on the expression of viral late genes [1]. The viral late proteins are mainly structural components that assist in the assembly and egress of newly formed infectious CMV virions [1]. The primary tegument proteins involved in assembly and egress are pp150, pp28, and UL97. pp150 directs the movement of the cytoplasmic capsids to the site for particle formation, while pp28 directs the enclosure of the tegument proteins and DNA-containing nucleocapsids within an enveloped particle [18,26,52]. UL97 phosphorylates the tegument proteins through its kinase activity, which may facilitate the incorporation of the tegument proteins into new infectious virions [18,30]. Once the virions are packaged, they are shed from the host cell through an exocytosis mechanism which uses the host cell's transport system to enclose vacuoles containing the newly synthesized infectious virions for release into the extracellular space.


**Gene**

**(Protein) Expression Essential for Lytic**

UL83 (pp65) Early-Late Dispensable

UL94 Late Augmentative/

UL96 Early Augmentative/

UL97 Early-Late Augmentative

IRS1/TRS1 Early-Late Augmentative/

**Table 1.** CMV tegument proteins and their known or inferred function.

**Replication**

Essential

Essential

US22 Early Dispensable Involved in events immediately after virus

**4. Cytomegalovirus tegument proteins as potential antiviral targets**

US23 Early Augmentative Colocalization with pp65 [57] US24 Early Augmentative Activation of viral gene expression [56]

Since the CMV tegument proteins play pivotal roles in all stages of the lytic stage of the viral life cycle, they are candidates for novel antiviral treatments. An antiviral agent able to bind to

UL77 Early Essential DNA packaging/cleavage [44] UL79 Early-Late Essential Promotes the accumulation of late viral transcripts [45]

UL84 Early Essential CMV DNA replication [48] UL88 Late Dispensable Unknown N/A UL93 Late Essential Virion packaging [49]

UL99 (pp28) Late Essential Directs the enclosure of enveloped virus particles [52] UL103 Late Augmentative Regulates virus particle and dense body egress [53] UL112 Early Augmentative CMV DNA replication [54]

UL82 (pp71) Immediate-Early Augmentative Degrades Daxx; facilitates Immediate-Early gene

**Known or Inferred Function Reference**

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[46]

117

[47,58,59]

[55]

[23]

expression

Cytomegalovirus Tegument Proteins and the Development of Novel Antiviral Therapeutics

Endogenous kinase activity

Associated kinase activity Evasion of adaptive immunity Evasion of innate immunity

Essential Putative DNA-binding protein [50]

Preserves the integrity of the nucleocapsid during translocation from the nucleus to the cytoplasm [51]

Kinase that phosphorylates UL44

Cyclin-dependent kinase-like functions

Inhibits PKR antiviral response

Virion assembly

penetration

Stimulates DNA replication, assembly, and egress [30,60,61]


**Table 1.** CMV tegument proteins and their known or inferred function.

**Gene**

**(Protein) Expression Essential for Lytic**

116 Manifestations of Cytomegalovirus Infection

UL47 Late Augmentative

UL48 Late Essential

UL69 Early-Late Augmentative

UL71 Early-Late Augmentative/

UL76 Early Augmentative/

**Replication**

UL23 Early-Late Dispensable Involved in events immediately after virus

UL24 Early-Late Dispensable Involved in events immediately after virus

UL32 (pp150) Late Essential Virion egress (directs capsid to the site of final

UL36 Immediate-Early Dispensable Control of a caspase-independent cell death

UL43 Late Dispensable Involved in events immediately after virus

UL44 Early Essential CMV DNA polymerase processivity/transcription

UL45 Late Augmentative Influences virus growth at low multiplicities of

UL25 Late Dispensable Structural protein [25] UL26 Early-Late Augmentative Transcriptional activation [24]

UL35 Late Augmentative Viral replication and particle formation [27]

UL38 Immediate-Early Augmentative Control of apoptosis [29]

UL50 Early Essential Egress of nucleocapsids [35] UL53 Late Essential Egress of nucleocapsids [36] UL54 Early Essential CMV DNA polymerase [37] UL56 Early-Late Dispensable DNA packaging [38] UL57 Early Essential Single-stranded DNA-binding protein [39]

UL72 Late Dispensable Inactive [42]

**Known or Inferred Function Reference**

envelopment) [26]

pathway [28]

factor [31]

infection [32]

[23]

[23]

[23]

[33]

[34]

[40]

penetration

penetration

penetration

Release of viral DNA from nucleocapsid

Disassembling of virus particles

Deubiquitinating protease

Release of viral DNA from capsid

Nuclear export of unspliced mRNAs

Arrests cell cycle in G1 phase

Essential Late envelopment [41]

Essential Modulation of gene expression [43]

#### **4. Cytomegalovirus tegument proteins as potential antiviral targets**

Since the CMV tegument proteins play pivotal roles in all stages of the lytic stage of the viral life cycle, they are candidates for novel antiviral treatments. An antiviral agent able to bind to a major tegument protein and inhibit its function would prevent CMV from replicating its viral DNA genome and producing new infectious virions. This would have great therapeutic value. Examples of how tegument proteins could be targeted therapeutically are presented below (See Figure 3).

[74]. Another tegument protein may bind to pp65,, inducing a conformational change that allows the inaccessible nuclear localization signal to be recognized by nuclear transport molecules, triggering the characteristic nuclear localization of pp65 and the initiation of the lytic cycle [71,72]. Importantly pp65 co-localizes with the tegument protein associated with the CMV US23 gene product [57]. Thus, the US23 gene product could be the other tegument protein necessary for pp65 to enter the nucleoli (also see section 4.2 UL97). Thus, two mono‐ clonal antibodies could be developed to target antigens present on the surfaces of pp65 and the US23 gene product, which would prevent them from interacting and inhibit the develop‐

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119

Additionally, pp65 can also be used to develop a vaccine to prevent or inhibit CMV infection. An excellent example of pp65 being utilized to develop a novel vaccine to prevent CMV infection concerns the two plasmid DNA vaccine, ASP0113. Currently, ASP0113 is in Phase I/ II clinical trials to prevent CMV infection in solid organ transplant recipients at high risk for CMV infection. The vaccine is comprised of the highly immunogenic pp65 tegument protein and the gB CMV surface protein, which utilizes the ability of pp65 to induce cell-mediated response and gB to induce humoral immune system responses in those infected with CMV. Results show a reduction in the number of CMV episodes and the time to initial viremia [75].

The UL97 gene product is also a tegument protein that could be targeted for the development of a novel antiviral therapeutic. UL97 stimulates DNA replication, assembly, and egress in addition to being a known kinase homologue [30,76]. UL97's kinase activity makes CMV susceptible to the current CMV antiviral ganciclovir, a synthetic 2'-deoxy-guanosine analogue. UL97 phosphorylates this synthetic analog to a deoxyguanosine triphosphate analogue, which competitively inhibits the incorporation of it by viral DNA polymerase. This competitive

Currently, a specific inhibitor of UL97 protein kinase activity, maribavir, inhibits viral replication and is in clinical trials [78]. Maribavir is a benzimidazole riboside and inhibits CMV DNA assembly as well as the egress of CMV nucleocapsids from infected host cells [78]. Maribavir was given fast track status by the Food and Drug Administration and is being investigated in Phase 2 clinical trials using a high dose treatment option for clinically significant

The UL97 gene product also shows due to its association with pp65. UL97 and pp65 act directly to form a complex during viral replication. When UL97 is genetically ablated or pharmaco‐ logically inhibited, pp65 localizes in unusual refractile bodies, which suggests that UL97 is essential for the successful localization of pp65 to the nucleus of the host cell at the beginning of the lytic stage of the viral life cycle [79]. Similarly to US23, UL97 may direct pp65 into the nucleus to initiate the lytic stage of CMV replication [71,72]. Furthermore, a pp65 deletion mutant exhibits modest resistance to maribavir [80]. pp65 may negatively regulate UL97 by sequestering kinase that would be available to promote viral replication [81]. The interaction between pp65 and UL97 could influence pp65-mediated immune evasion, because the

inhibition results in the termination of CMV DNA elongation [77].

ment of the lytic stage of the CMV life cycle.

**4.2. UL97**

CMV viremia.

**Figure 3.** Current and developmental antiviral agents that target acute CMV infection.

#### **4.1. pp65**

A good tegument protein to target would be pp65, since it is the most abundant tegu‐ ment protein [67]. pp65 is implicated in counteracting both innate and adaptive immune responses during CMV infections. It invokes humoral and cellular immunity and is the dominant target antigen of cytotoxic T lymphocytes [67]. In addition to pp65 being antigenic, it can also be considered a good antiviral target due to its immunomodulatory role. pp65 prevents immediate-early proteins from being recognized by components of the immune system in addition to inhibiting the synthesis of the various components in‐ volved in the host cell's immune response through its associated enzymatic kinase activity [58,59]. Thus, if you can inhibit the function of pp65, the host cell immune response would be able to inhibit the CMV viral life cycle.

Recent evidence in support of pp65 as a target for a novel antiviral treatment strategy concerns its subcellular localization during the lytic stage of the viral life cycle. pp65 migrates to the nucleoli at the early stages of infection, which suggests a functional relationship between its localization and the lytic stage of the viral life cycle [68]. However, pp65 begins to migrate to the cytoplasm 48 hours into the lytic cycle through cyclin-dependent kinase activity and a Crm 1 exporter mediated migration [69,70]. It is likely that pp65 does not migrate independently to the nucleoli as it remains in the cytoplasm in the absence of other components of CMV [71, 72]. This is significant as the localization patterns of the tegument proteins are correlated with their function [73]. Furthermore, pp65 has a bipartite nuclear localization signal, which implies that the nuclear localization signal is in a region that is initially inaccessible to importin proteins [74]. Another tegument protein may bind to pp65,, inducing a conformational change that allows the inaccessible nuclear localization signal to be recognized by nuclear transport molecules, triggering the characteristic nuclear localization of pp65 and the initiation of the lytic cycle [71,72]. Importantly pp65 co-localizes with the tegument protein associated with the CMV US23 gene product [57]. Thus, the US23 gene product could be the other tegument protein necessary for pp65 to enter the nucleoli (also see section 4.2 UL97). Thus, two mono‐ clonal antibodies could be developed to target antigens present on the surfaces of pp65 and the US23 gene product, which would prevent them from interacting and inhibit the develop‐ ment of the lytic stage of the CMV life cycle.

Additionally, pp65 can also be used to develop a vaccine to prevent or inhibit CMV infection. An excellent example of pp65 being utilized to develop a novel vaccine to prevent CMV infection concerns the two plasmid DNA vaccine, ASP0113. Currently, ASP0113 is in Phase I/ II clinical trials to prevent CMV infection in solid organ transplant recipients at high risk for CMV infection. The vaccine is comprised of the highly immunogenic pp65 tegument protein and the gB CMV surface protein, which utilizes the ability of pp65 to induce cell-mediated response and gB to induce humoral immune system responses in those infected with CMV. Results show a reduction in the number of CMV episodes and the time to initial viremia [75].

#### **4.2. UL97**

a major tegument protein and inhibit its function would prevent CMV from replicating its viral DNA genome and producing new infectious virions. This would have great therapeutic value. Examples of how tegument proteins could be targeted therapeutically are presented below

A good tegument protein to target would be pp65, since it is the most abundant tegu‐ ment protein [67]. pp65 is implicated in counteracting both innate and adaptive immune responses during CMV infections. It invokes humoral and cellular immunity and is the dominant target antigen of cytotoxic T lymphocytes [67]. In addition to pp65 being antigenic, it can also be considered a good antiviral target due to its immunomodulatory role. pp65 prevents immediate-early proteins from being recognized by components of the immune system in addition to inhibiting the synthesis of the various components in‐ volved in the host cell's immune response through its associated enzymatic kinase activity [58,59]. Thus, if you can inhibit the function of pp65, the host cell immune response would

Recent evidence in support of pp65 as a target for a novel antiviral treatment strategy concerns its subcellular localization during the lytic stage of the viral life cycle. pp65 migrates to the nucleoli at the early stages of infection, which suggests a functional relationship between its localization and the lytic stage of the viral life cycle [68]. However, pp65 begins to migrate to the cytoplasm 48 hours into the lytic cycle through cyclin-dependent kinase activity and a Crm 1 exporter mediated migration [69,70]. It is likely that pp65 does not migrate independently to the nucleoli as it remains in the cytoplasm in the absence of other components of CMV [71, 72]. This is significant as the localization patterns of the tegument proteins are correlated with their function [73]. Furthermore, pp65 has a bipartite nuclear localization signal, which implies that the nuclear localization signal is in a region that is initially inaccessible to importin proteins

**Figure 3.** Current and developmental antiviral agents that target acute CMV infection.

be able to inhibit the CMV viral life cycle.

(See Figure 3).

118 Manifestations of Cytomegalovirus Infection

**4.1. pp65**

The UL97 gene product is also a tegument protein that could be targeted for the development of a novel antiviral therapeutic. UL97 stimulates DNA replication, assembly, and egress in addition to being a known kinase homologue [30,76]. UL97's kinase activity makes CMV susceptible to the current CMV antiviral ganciclovir, a synthetic 2'-deoxy-guanosine analogue. UL97 phosphorylates this synthetic analog to a deoxyguanosine triphosphate analogue, which competitively inhibits the incorporation of it by viral DNA polymerase. This competitive inhibition results in the termination of CMV DNA elongation [77].

Currently, a specific inhibitor of UL97 protein kinase activity, maribavir, inhibits viral replication and is in clinical trials [78]. Maribavir is a benzimidazole riboside and inhibits CMV DNA assembly as well as the egress of CMV nucleocapsids from infected host cells [78]. Maribavir was given fast track status by the Food and Drug Administration and is being investigated in Phase 2 clinical trials using a high dose treatment option for clinically significant CMV viremia.

The UL97 gene product also shows due to its association with pp65. UL97 and pp65 act directly to form a complex during viral replication. When UL97 is genetically ablated or pharmaco‐ logically inhibited, pp65 localizes in unusual refractile bodies, which suggests that UL97 is essential for the successful localization of pp65 to the nucleus of the host cell at the beginning of the lytic stage of the viral life cycle [79]. Similarly to US23, UL97 may direct pp65 into the nucleus to initiate the lytic stage of CMV replication [71,72]. Furthermore, a pp65 deletion mutant exhibits modest resistance to maribavir [80]. pp65 may negatively regulate UL97 by sequestering kinase that would be available to promote viral replication [81]. The interaction between pp65 and UL97 could influence pp65-mediated immune evasion, because the presentation of viral immediate-early proteins to T cells is blocked when the proteins are phosphorylated by UL97 kinase [81,82].

The gene products of UL55 and UL75 by comparison have been shown to be involved Sp1 and NF-kappaB activation during the earliest stages of CMV infection via a cellular receptor-viral ligand interaction. This is based on the observation that the cellular transcription factors Sp1 and NF-kappaB are upregulated shortly after the binding of purified live or UV-inactivated CMV to the cell surface, which has also been seen in other systems where cellular factors are

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All tegument proteins elicit a strong humoral immune response [92]. This is significant, since the host immunological functions are clearly limit CMV-associated disease [93]. Novel therapeutics could take advantage of the highly immunogenic nature of the CMV structural proteins. Potentially, an antibody could be designed that recognizes the CMV antigens expressed on these proteins and could be exploited to deliver an active drug compound that can inhibit the lytic replication of the virus. This strategy is used to target certain cancers. Additionally, a monoclonal antibody could simply be used to help the immune system locate

Additionally, structural phosphoproteins, such as pp65 and pp150, are good candidates for subunit vaccine development, since they elicit cytotoxic T lymphocyte responses. A CMV subunit vaccine would contain viral antigens without the CMV DNA genome. It would be less likely to cause adverse reactions and would be clinically valuable in view of the high hema‐ tologic and renal toxicity and low bioavailability of current antiviral treatments targeting acute

Although it is not critical for viral replication unlike the majority of potential CMV targets, UL94 could also be targeted by a novel antiviral agent. Studies of UL94 stop mutants show that UL94 plays a role in the secondary envelopment of viral particles. When the UL94 gene is absent or not functioning, the UL99 (pp28) tegument protein responsible for the cytoplasmic envelopment of tegument proteins during assembly and egress exhibits aberrant localization and there is a complete block of secondary envelopment of virions. Thus, UL94 functions late in the CMV lytic life cycle to direct pp28 to the assembly complex, facilitating the secondary

If a molecule is able to target UL94 and inhibit its function, the assembly and egress of virion progeny will be blocked, since the secondary envelopment of CMV virions will not occur. A therapeutic targeting UL94 could utilize the interaction between UL94 and the pp28 structural protein. For example, a new antiviral could focus on the ability of pp28 to elicit a strong humoral immune response through the release of antibodies targeting the CMV specific immunoglobulin as mentioned above. Two monoclonal antibodies could also be developed to target pp28 and UL94 that could inhibit UL94 from directing pp28 to the assembly complex

where new CMV virion progeny undergo secondary envelopment.

induced following a receptor-ligand interaction [91].

CMV infection [94].

envelopment of CMV virions [95].

**4.5. UL94**

the CMV immunogenic structural proteins and end the CMV infection.

#### **4.3. pp71**

pp71 is also a major target for CMV antiviral research as it influences the activation of immediate-early gene expression at the start of the lytic cycle [83]. Mechanistically, pp71 activates viral gene expression through the neutralization of the effects of the cellular Daxx protein, which is recruited to promoters by DNA-binding transcription factors, resulting in the repression of viral transcription [84]. pp71 binds to two inherent domains on Daxx and induces its proteasomal degradation [85]. pp71 is slows the intracellular transport of MHC class I molecules, which limits the display of CMV antigens on the surface of infected cells to cytotoxic T lymphocytes [86].

A UL82 gene deletion mutant may serve as a potential novel CMV vaccine candidate as it can enter cells efficiently and activate the innate immune response through interactions with cell surface receptors. However viral gene expression is disrupted during infection when cells are infected at a low multiplicity of the UL82 gene deletion mutant. The expression of the imme‐ diate-early genes that are involved in the host anti-viral response is blocked. One of the genes whose expression would be blocked is the immediate-early 2 (IE2) gene that can antagonize the host innate immune response by attenuating the interferon β response and blocking chemokine expression. If the expression of IE2 is blocked, the number of cytotoxic T lympho‐ cytes and natural killer cells recruited to the infected cell would increase. Furthermore, viral replication is limited with low multiplicity of infection with the UL82 gene mutant as this would promote a robust anti-viral immune response. Thus, a novel antiviral treatment could target pp71 and its ability to control the activation of immediate-early gene expression [87].

#### **4.4. Tegument structural proteins**

The structural proteins of CMV with therapeutic potential include pp150, pp65 (above), pp28, pp38, and the gene products of UL55 and UL75, as they play pivotal roles in the CMV life cycle and are immunogenic. pp150, the second most abundant tegument protein behind pp65, plays a role in the assembly and egress of new infectious virus particles. It is necessary to incorporate nucleocapsids into these new infectious virus particles [21]. It is essential for maintaining the stability of the cytoplasmic capsids and directing their movement [1,88]. It also plays a role in the reorganization of the cytoplasmic assembly compartment during virion assembly [88]. pp28 is largely responsible for the cytoplasmic envelopment of tegument proteins and capsids during assembly and egress [89].

pp38 is a mitogen-activated protein kinase and has a critical function in CMV viral DNA replication. pp38 kinase activity is significantly increased after CMV infection, and inhibition of this kinase activity inhibits CMV-induced hyperphosphorylation of pRb and the phosphor‐ ylation of heat shock protein 27. This suggests that pp38 activation is involved in virusmediated changes in host cell metabolism throughout the CMV infection [90].

The gene products of UL55 and UL75 by comparison have been shown to be involved Sp1 and NF-kappaB activation during the earliest stages of CMV infection via a cellular receptor-viral ligand interaction. This is based on the observation that the cellular transcription factors Sp1 and NF-kappaB are upregulated shortly after the binding of purified live or UV-inactivated CMV to the cell surface, which has also been seen in other systems where cellular factors are induced following a receptor-ligand interaction [91].

All tegument proteins elicit a strong humoral immune response [92]. This is significant, since the host immunological functions are clearly limit CMV-associated disease [93]. Novel therapeutics could take advantage of the highly immunogenic nature of the CMV structural proteins. Potentially, an antibody could be designed that recognizes the CMV antigens expressed on these proteins and could be exploited to deliver an active drug compound that can inhibit the lytic replication of the virus. This strategy is used to target certain cancers. Additionally, a monoclonal antibody could simply be used to help the immune system locate the CMV immunogenic structural proteins and end the CMV infection.

Additionally, structural phosphoproteins, such as pp65 and pp150, are good candidates for subunit vaccine development, since they elicit cytotoxic T lymphocyte responses. A CMV subunit vaccine would contain viral antigens without the CMV DNA genome. It would be less likely to cause adverse reactions and would be clinically valuable in view of the high hema‐ tologic and renal toxicity and low bioavailability of current antiviral treatments targeting acute CMV infection [94].

#### **4.5. UL94**

presentation of viral immediate-early proteins to T cells is blocked when the proteins are

pp71 is also a major target for CMV antiviral research as it influences the activation of immediate-early gene expression at the start of the lytic cycle [83]. Mechanistically, pp71 activates viral gene expression through the neutralization of the effects of the cellular Daxx protein, which is recruited to promoters by DNA-binding transcription factors, resulting in the repression of viral transcription [84]. pp71 binds to two inherent domains on Daxx and induces its proteasomal degradation [85]. pp71 is slows the intracellular transport of MHC class I molecules, which limits the display of CMV antigens on the surface of infected cells to

A UL82 gene deletion mutant may serve as a potential novel CMV vaccine candidate as it can enter cells efficiently and activate the innate immune response through interactions with cell surface receptors. However viral gene expression is disrupted during infection when cells are infected at a low multiplicity of the UL82 gene deletion mutant. The expression of the imme‐ diate-early genes that are involved in the host anti-viral response is blocked. One of the genes whose expression would be blocked is the immediate-early 2 (IE2) gene that can antagonize the host innate immune response by attenuating the interferon β response and blocking chemokine expression. If the expression of IE2 is blocked, the number of cytotoxic T lympho‐ cytes and natural killer cells recruited to the infected cell would increase. Furthermore, viral replication is limited with low multiplicity of infection with the UL82 gene mutant as this would promote a robust anti-viral immune response. Thus, a novel antiviral treatment could target pp71 and its ability to control the activation of immediate-early gene expression [87].

The structural proteins of CMV with therapeutic potential include pp150, pp65 (above), pp28, pp38, and the gene products of UL55 and UL75, as they play pivotal roles in the CMV life cycle and are immunogenic. pp150, the second most abundant tegument protein behind pp65, plays a role in the assembly and egress of new infectious virus particles. It is necessary to incorporate nucleocapsids into these new infectious virus particles [21]. It is essential for maintaining the stability of the cytoplasmic capsids and directing their movement [1,88]. It also plays a role in the reorganization of the cytoplasmic assembly compartment during virion assembly [88]. pp28 is largely responsible for the cytoplasmic envelopment of tegument proteins and capsids

pp38 is a mitogen-activated protein kinase and has a critical function in CMV viral DNA replication. pp38 kinase activity is significantly increased after CMV infection, and inhibition of this kinase activity inhibits CMV-induced hyperphosphorylation of pRb and the phosphor‐ ylation of heat shock protein 27. This suggests that pp38 activation is involved in virus-

mediated changes in host cell metabolism throughout the CMV infection [90].

phosphorylated by UL97 kinase [81,82].

120 Manifestations of Cytomegalovirus Infection

cytotoxic T lymphocytes [86].

**4.4. Tegument structural proteins**

during assembly and egress [89].

**4.3. pp71**

Although it is not critical for viral replication unlike the majority of potential CMV targets, UL94 could also be targeted by a novel antiviral agent. Studies of UL94 stop mutants show that UL94 plays a role in the secondary envelopment of viral particles. When the UL94 gene is absent or not functioning, the UL99 (pp28) tegument protein responsible for the cytoplasmic envelopment of tegument proteins during assembly and egress exhibits aberrant localization and there is a complete block of secondary envelopment of virions. Thus, UL94 functions late in the CMV lytic life cycle to direct pp28 to the assembly complex, facilitating the secondary envelopment of CMV virions [95].

If a molecule is able to target UL94 and inhibit its function, the assembly and egress of virion progeny will be blocked, since the secondary envelopment of CMV virions will not occur. A therapeutic targeting UL94 could utilize the interaction between UL94 and the pp28 structural protein. For example, a new antiviral could focus on the ability of pp28 to elicit a strong humoral immune response through the release of antibodies targeting the CMV specific immunoglobulin as mentioned above. Two monoclonal antibodies could also be developed to target pp28 and UL94 that could inhibit UL94 from directing pp28 to the assembly complex where new CMV virion progeny undergo secondary envelopment.

#### **4.6. UL56**

Currently, all of the licensed drugs used for the systemic treatment of acute CMV infection act through similar mechanisms as they target the viral DNA polymerase (UL54) [96]. With the emergence of ganciclovir-resistant strains of CMV, as well as cross-resistance to second-line agents (foscarnet and cidofovir), there is a need for new drugs [97].

that would inhibit the CMV lytic cycle and eradicate the virus from host cells. The most likely targets within the CMV virion are those proteins found within the tegument, which is a unique structure found in all members of the *Herpesviridae* family. Proteins that localize to the tegument play pivotal roles in all stages of the CMV life cycle. Novel antiviral therapeutics that target these proteins inhibit the CMV lytic cycle. Furthermore, the highly immunogenic nature of several tegument proteins makes them excellent candidates for subunit vaccines. In fact, several novel antiviral therapeutics and CMV vaccines based around the CMV tegument proteins are under development. Nonetheless, more research needs to be done to fully identify

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Developmental Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA, USA

[1] arski, E. S., T. Shenk, and R. F. Pass. Cytomegaloviruses. In D. M. Knipe and P. M. Howley (ed.), Fields virology, 5th ed. Lippincott Williams & Wilkins, Philadelphia,

[2] Selinsky C, Luke C, Wloch M, Geall A, Hermanson G, et al. A DNA-based vaccine for the prevention of human cytomegalovirus-associated diseases. Human Vaccines

[3] Sinzger, C., A. Grefte, B. Plachter, A. S. H. Gouw, T. H. The, and G. Jahn. Fibroblasts, epithelial cells, endothelial cells, and smooth muscle cells are major targets of human cytomegalovirus infection in lung and gastrointestinal tissues. J. Gen. Virol. 76; 1995.

[4] Steininger, C. Clinical relevance of cytomegalovirus infection in patients with disor‐

[5] Rafailidis PI, Mourtzoukou EG, Varbobitis IC, et al. Severe cytomegalovirus infection in apparently immunocompetent patients: a systematic review. Virol J. 5; 2008; p47.

[6] Naucler C. Does cytomegalovirus play a causative role in the development of various

[7] Koch, S., R. Solana, O. Dela Rosa, and G. Pawelec. Human cytomegalovirus infection and T cell immunosenescence: a mini review. Mech. Ageing Dev. 127; 2006; p538-543.

ders of the immune system. Clin. Microbiol. Infect. 13; 2007. p953-963.

inflammatory diseases and cancer? J. Intern. Med. 259; 2006; p219-246.

the function as well as the role in the lytic stage of the CMV life cycle.

Address all correspondence to: jpt015@bucknell.edu

**Author details**

**References**

John Paul III Tomtishen

PA; 2007. p2701-2772.

1; 2005. p16-23.

p741-750.

A promising small molecule antiviral candidate, AIC246, is representative of the 3,4 dihydroquinazoline nonnucleoside CMV inhibitors [98]. AIC246 acts through a unique mechanism distinct from that of the CMV DNA polymerase inhibitors. AIC246 blocks viral replication without inhibiting the synthesis of progeny CMV genomic DNA or viral proteins. Three pieces of evidence show AIC246 interferes with CMV DNA cleavage/packaging via a distinct molecular mechanism from other compounds that target the CMV viral terminase [99]. First, AIC246 does not affect CMV protein expression or CMV DNA replication, excluding the possibility of AIC246 acting through interfering with viral genome replication [99]. Second, genetic mapping of AIC246 resistance to the CMV open reading frame of UL56 shows that the viral terminase complex is involved in the action of AIC246 [99]. Third, a terminase cleavage assay showed potent inhibition of the formation of properly processed unit-length genomes [99]. Thus, AIC246 is a promising therapeutic candidate for the treatment of acute CMV infection through its unique mechanism of action involving the UL56 tegument protein involved in DNA packaging.

#### **4.7. Antisense oligonucleotides**

The expression of viral genes encoding proteins essential for the production of infectious virions can also be targeted. Fomivirsen, a 21-base phosphorothioate oligodeoxynucleotide complementary to the messenger RNA (mRNA) of the major immediate-early region proteins of CMV, can inhibit CMV gene expression through an antisense mechanism. Fomivirsen binds to the target mRNA transcripts of the immediate-early region 2 (IE2) that encodes several proteins responsible for the regulation of viral gene expression. This binding inhibits IE2 protein synthesis and the activation of immediate-early gene expression by pp71, which subsequently inhibits viral replication [100]. Fomivirsen is licensed to treat acute CMV infection and illustrates that CMV tegument proteins can targeted indirectly.

#### **5. Conclusion**

CMV infects most individuals by early adulthood and is associated with morbidity and mortality, especially in those with poor immune systems. Furthermore, CMV has been implicated in inflammatory and proliferative diseases, such as cardiovascular disease and cancer. Antiviral agents able to inhibit the CMV replication cycle and the production of new infectious virions exist, but suffer from high levels of toxicity and low levels of bioavailability. CMV resistant and cross-resistant strains develop because all drugs target the viral DNA polymerase UL54. There is also no vaccine available to prevent acute CMV infection. However, several components of the CMV virion are promising targets for novel antiviral therapeutics that would inhibit the CMV lytic cycle and eradicate the virus from host cells. The most likely targets within the CMV virion are those proteins found within the tegument, which is a unique structure found in all members of the *Herpesviridae* family. Proteins that localize to the tegument play pivotal roles in all stages of the CMV life cycle. Novel antiviral therapeutics that target these proteins inhibit the CMV lytic cycle. Furthermore, the highly immunogenic nature of several tegument proteins makes them excellent candidates for subunit vaccines. In fact, several novel antiviral therapeutics and CMV vaccines based around the CMV tegument proteins are under development. Nonetheless, more research needs to be done to fully identify the function as well as the role in the lytic stage of the CMV life cycle.

#### **Author details**

**4.6. UL56**

122 Manifestations of Cytomegalovirus Infection

involved in DNA packaging.

**5. Conclusion**

**4.7. Antisense oligonucleotides**

Currently, all of the licensed drugs used for the systemic treatment of acute CMV infection act through similar mechanisms as they target the viral DNA polymerase (UL54) [96]. With the emergence of ganciclovir-resistant strains of CMV, as well as cross-resistance to second-line

A promising small molecule antiviral candidate, AIC246, is representative of the 3,4 dihydroquinazoline nonnucleoside CMV inhibitors [98]. AIC246 acts through a unique mechanism distinct from that of the CMV DNA polymerase inhibitors. AIC246 blocks viral replication without inhibiting the synthesis of progeny CMV genomic DNA or viral proteins. Three pieces of evidence show AIC246 interferes with CMV DNA cleavage/packaging via a distinct molecular mechanism from other compounds that target the CMV viral terminase [99]. First, AIC246 does not affect CMV protein expression or CMV DNA replication, excluding the possibility of AIC246 acting through interfering with viral genome replication [99]. Second, genetic mapping of AIC246 resistance to the CMV open reading frame of UL56 shows that the viral terminase complex is involved in the action of AIC246 [99]. Third, a terminase cleavage assay showed potent inhibition of the formation of properly processed unit-length genomes [99]. Thus, AIC246 is a promising therapeutic candidate for the treatment of acute CMV infection through its unique mechanism of action involving the UL56 tegument protein

The expression of viral genes encoding proteins essential for the production of infectious virions can also be targeted. Fomivirsen, a 21-base phosphorothioate oligodeoxynucleotide complementary to the messenger RNA (mRNA) of the major immediate-early region proteins of CMV, can inhibit CMV gene expression through an antisense mechanism. Fomivirsen binds to the target mRNA transcripts of the immediate-early region 2 (IE2) that encodes several proteins responsible for the regulation of viral gene expression. This binding inhibits IE2 protein synthesis and the activation of immediate-early gene expression by pp71, which subsequently inhibits viral replication [100]. Fomivirsen is licensed to treat acute CMV

CMV infects most individuals by early adulthood and is associated with morbidity and mortality, especially in those with poor immune systems. Furthermore, CMV has been implicated in inflammatory and proliferative diseases, such as cardiovascular disease and cancer. Antiviral agents able to inhibit the CMV replication cycle and the production of new infectious virions exist, but suffer from high levels of toxicity and low levels of bioavailability. CMV resistant and cross-resistant strains develop because all drugs target the viral DNA polymerase UL54. There is also no vaccine available to prevent acute CMV infection. However, several components of the CMV virion are promising targets for novel antiviral therapeutics

infection and illustrates that CMV tegument proteins can targeted indirectly.

agents (foscarnet and cidofovir), there is a need for new drugs [97].

John Paul III Tomtishen

Address all correspondence to: jpt015@bucknell.edu

Developmental Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA, USA

#### **References**


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### *Edited by Patricia Price, Nandini Makwana and Samantha Brunt*

Cytomegalovirus (CMV) is carried by 50 100% of the worlds population throughout their lives. Consequences are most readily seen in immunocompromised individuals such as organ transplant recipients, HIV-infected patients and new born infants. This book gives an in-depth view of manifestations of CMV infection in immunocompromised individuals: how it affects the immune system and how it is diagnosed and treated. The book also sheds light on the epidemiology and impact of CMV in sub-Saharan Africa, and also associations with age related disease that are more commonly seen in the western world. It particularly details a recent discovery between CMV and tumour immuno-biology. The book explores the development of a few compounds and also highlights the need to discover novel antiviral agents in future.

Photo by Dr\_Microbe / iStock

Manifestations of Cytomegalovirus Infection

Manifestations of

Cytomegalovirus Infection

*Edited by Patricia Price,* 

*Nandini Makwana and Samantha Brunt*