**Antiviral Therapy in HCV-Infected Decompensated Cirrhotics**

Fazal-I-Akbar Danish

*Quaid-e-Azam University, Islamabad, Pakistan* 

#### **1. Introduction**

**What we are dealing with:** Hepatitis C virus (HCV) infection is the commonest blood-borne infection, one of the commonest cause of chronic liver disease (CLD) & hepatocellular carcinoma (HCC) and one of the commonest reason for liver transplantation (LT) the world over.

**What is the meaning of decompensation**: Fibrosis is the histopathological hallmark of chronic hepatitis causing progressive derangement of normal liver architecture with consequent reduction in hepatic synthetic function. CLD is said to be decompensated when one or the other complication of CLD has developed - ascites, variceal bleeding (secondary to portal hypertension), impaired hepatic synthetic function (hypoalbuminemia), jaundice, and/or hepatic encephalopathy. Five years survival rate in decompensated cirrhotics is estimated to be 50%.1

**Decompensated cirrhosis is NOT a contraindication to antiviral therapy:**  Decompensated cirrhosis has traditionally been considered a contraindication to interferon and ribavirin therapy. Whereas, the same may be true for advanced cirrhosis (which is only successfully amenable to LT), there are reports in the literature in which antiviral therapy was given *successfully* in selected cases of *early* hepatic decompensation with an aim to attain sustained viral clearance (SVR), halt disease progression and expect potential (though often partial) recovery of hepatic metabolic function. Antiviral therapy may also be instituted to prevent hepatitis C recurrence post-transplantation. If HCV is not eradicated pre-transplantation, reinfection with HCV occurs in *all* transplant recipients *as a rule*, with secondary cirrhosis developing in approximately 30% of cases within 5 years.2 Pre-transplantation HCV eradication is however associated with less likelihood of reinfection and this forms the rationale for treating decompensated cirrhotics awaiting LT with antiviral therapy.3 Initiating pre-emptive post-transplantation antiviral therapy, and treating established post-transplant HCV hepatitis are other options in LT patients. The aim of instituting pre-transplantation antiviral therapy is either to attain a sustained virological response (SVR) at transplantation, or an *on-treatment* HCV RNA clearance at transplantation. Mere reduction of viral load should *not* be the aim because, unlike HBV cirrhotics, this has not been shown to decrease the rate &/or severity of posttransplant HCV recurrence.

Antiviral Therapy in HCV-Infected Decompensated Cirrhotics 5

by decompensated cirrhotics with reasonable rates of attainment of end-of-treatment

1. In one study,7 39% of the patients receiving low, accelerating regimen of non-pegylated interferon plus ribavirin experienced clearance of HCV-RNA, & 21% attained an SVR. Results with pegylated interferon are even better. In the first study12 *proving* the benefits of antiviral therapy in cirrhotics with signs of portal hypertension, 51 cirrhotics received 1mg/kg/wk of pegylated-interferon alpha-2b plus oral ribavirin at a fixed dose of 800mg/d for 52 wks. By intention-to-treat analysis, SVR was achieved in 21.6% patients. As otherwise, patients with genotypes 2 & 3 showed better results (83.3%) than genotype 1 cases (13.3%). Although antiviral therapy was stopped in 5 of the patients because of neutrophil counts falling below 0.75×103/dL, none of them developed superadded infections. The disease deteriorated in only 6% of those who attained SVR

2. In another study,10 Peg-IFN alpha-2b (1.0 mg/kg/wk) plus standard dose of ribavirin were administered to all patients for 24 wks *regardless of the genotype*. The overall SVR rate attained even with this *suboptimal dose* regimen was 19.7%. Except patients with very advanced liver disease (CTP score >10), none experienced life-threatening complications. Peg-IFN and ribavirin in the standard dosage (Peg-IFN alpha-2b 1.5mg/kg & ribavirin 800-1000mg for genotypes 2 and 3, and 1000-1200mg for genotypes 1 and 4) for the standard duration of time (48 & 24 wks for genotype 1 &

3. In another study,13 35% of end-stage cirrhotics cleared the HCV infection (16% genotype 1 & 4, and 59% genotype 2 & 3 cases). 60% of all patients tolerated the antiviral therapy without any major untoward effects; treatment was discontinued in 19.1% of the

5. In a recent study15 aimed to evaluate both the prevention of post-transplantation HCV recurrence & the risk of bacterial infections during therapy, 47% patients achieved HCV RNA negativity *during* treatment, 29% were HCV RNA negative *at the time of transplantation* (drop outs *n*=3, deaths *n*=4, viral relapse *n*=2) and 20% achieved an SVR *post-transplantation*. Importantly, none of the patients who achieved SVR pre-

**3. Evidence-based pharmacotherapy of HCV infection in decompensated** 

Child–Pugh (sometimes called Child-Turcotte-Pugh [CTP]) scoring – see table 1 - helps

1. The ideal candidate for antiviral therapy remains a patient with Child–Pugh class A disease in whom the risk of drug-induced side effects is almost identical to that of the controls. Nonetheless, all cirrhotic patients with a CTP score ≤9 and a decompensated event that abated with routine management may be considered for antiviral therapy.

patients with 4 among those ending up having severe superadded infections. 4. In yet another study14 a 48 week course was planned for patients who demonstrated EVR with a standard regimen of PEG-IFN alfa-2a (135µg, once a week) plus ribavirin (1000-1200 mg/day). Results showed 60% patients completing the course with ETR &

response (ETR) & sustained virological response (SVR):4,7,10,11

compared to 38% of the non-responders.

non-1, respectively) has also been tried.

SVR achieved in 45% & 35% cases, respectively.

**cirrhotics** 

transplantation developed a recurrence post-transplantation.

determine the need and utility of instituting antiviral therapy:

Thus decompensation per se is not an absolute contraindication for antiviral therapy. Although the final SVR rates attained in such patients are lower,21,23 successful antiviral therapy is potentially lifesaving which supports the rationale for implementing HCV treatment in these patients.

In this chapter, the pros and cons of antiviral therapy in decompensated liver cirrhosis are reviewed with special emphasis on how to avoid antiviral dose reductions/ withdrawals secondary to the development of haematologic side effects by using haematopoietic growth factors (HGF's).

#### **2. Discussion**

#### **2.1 Therapeutic options in decompensated cirrhosis**

In selected cases, HCV-infected decompensated cirrhosis may be treated surgically (i.e. with LT) &/or medically (i.e. with antiviral therapy).

#### **2.2 Surgical option**

**LT: How feasible is this option?** LT is not a feasible option in the great majority of cirrhotics. This is not only because of the limited number of organ donors available at a given time, but also because of the age-related cardiovascular, renal, and pulmonary derangements that practically make going for this option rather *irrational* at times. Additionally, old age (≥65 years) is generally considered an exclusion criterion for LT.

#### **2.3 Medical option**

**Historical reasons for reluctance to institute medical therapy in decompensated cirrhotics:**  Historically, despite the known theoretical benefits of antiviral therapy (improvement in liver histology, partial reversal of established cirrhosis, and prevention of life-threatening complications), most decompensated cirrhotics have not been offered antiviral therapy. Primarily, this has been due to the concerns regarding the therapeutic efficacy and safety of antiviral therapy in such cases. Peginterferon-ribavirin combination therapy is known to have *limited efficacy* in decompensated cirrhotics.4,5 Also, compared to non-cirrhotics, such patients are more prone to develop *hematologic side effects* (neutropenia, thrombocytopenia & anemia) with antiviral therapy.6 In fact, patients who already have severe neutropenia or thrombocytopenia (neutrophil count <1500/mm3 or platelets count <75,000/mm3) are highly prone to develop life-threatening infections after starting antiviral therapy, particularly if they have Child–Pugh class C disease.7,8 Also, it is generally thought that agerelated derangements in cardiovascular and pulmonary functions make the cirrhotic patients less tolerant to ribavirin-induced hemolytic anemia. Finally, there are concerns that decompensation may worsen with antiviral therapy as is the case with decompensated chronic hepatitis B cases.9

**Do the reasons for reluctance evidence-based:** Current literature reviews shows that because of the unstandardized dosage schedules being administered over variable periods of time in the past studies, we may have actually under/ overestimated the potential benefits and risks of antiviral therapy respectively in decompensated cirrhotics. There are now several reports in the literature in which antiviral therapy was relatively well tolerated

Thus decompensation per se is not an absolute contraindication for antiviral therapy. Although the final SVR rates attained in such patients are lower,21,23 successful antiviral therapy is potentially lifesaving which supports the rationale for implementing HCV

In this chapter, the pros and cons of antiviral therapy in decompensated liver cirrhosis are reviewed with special emphasis on how to avoid antiviral dose reductions/ withdrawals secondary to the development of haematologic side effects by using haematopoietic growth

In selected cases, HCV-infected decompensated cirrhosis may be treated surgically (i.e. with

**LT: How feasible is this option?** LT is not a feasible option in the great majority of cirrhotics. This is not only because of the limited number of organ donors available at a given time, but also because of the age-related cardiovascular, renal, and pulmonary derangements that practically make going for this option rather *irrational* at times. Additionally, old age (≥65 years) is generally considered an exclusion criterion for LT.

**Historical reasons for reluctance to institute medical therapy in decompensated cirrhotics:**  Historically, despite the known theoretical benefits of antiviral therapy (improvement in liver histology, partial reversal of established cirrhosis, and prevention of life-threatening complications), most decompensated cirrhotics have not been offered antiviral therapy. Primarily, this has been due to the concerns regarding the therapeutic efficacy and safety of antiviral therapy in such cases. Peginterferon-ribavirin combination therapy is known to have *limited efficacy* in decompensated cirrhotics.4,5 Also, compared to non-cirrhotics, such patients are more prone to develop *hematologic side effects* (neutropenia, thrombocytopenia & anemia) with antiviral therapy.6 In fact, patients who already have severe neutropenia or thrombocytopenia (neutrophil count <1500/mm3 or platelets count <75,000/mm3) are highly prone to develop life-threatening infections after starting antiviral therapy, particularly if they have Child–Pugh class C disease.7,8 Also, it is generally thought that agerelated derangements in cardiovascular and pulmonary functions make the cirrhotic patients less tolerant to ribavirin-induced hemolytic anemia. Finally, there are concerns that decompensation may worsen with antiviral therapy as is the case with decompensated

**Do the reasons for reluctance evidence-based:** Current literature reviews shows that because of the unstandardized dosage schedules being administered over variable periods of time in the past studies, we may have actually under/ overestimated the potential benefits and risks of antiviral therapy respectively in decompensated cirrhotics. There are now several reports in the literature in which antiviral therapy was relatively well tolerated

treatment in these patients.

**2.1 Therapeutic options in decompensated cirrhosis** 

LT) &/or medically (i.e. with antiviral therapy).

factors (HGF's).

**2. Discussion** 

**2.2 Surgical option** 

**2.3 Medical option** 

chronic hepatitis B cases.9

by decompensated cirrhotics with reasonable rates of attainment of end-of-treatment response (ETR) & sustained virological response (SVR):4,7,10,11


#### **3. Evidence-based pharmacotherapy of HCV infection in decompensated cirrhotics**

Child–Pugh (sometimes called Child-Turcotte-Pugh [CTP]) scoring – see table 1 - helps determine the need and utility of instituting antiviral therapy:

1. The ideal candidate for antiviral therapy remains a patient with Child–Pugh class A disease in whom the risk of drug-induced side effects is almost identical to that of the controls. Nonetheless, all cirrhotic patients with a CTP score ≤9 and a decompensated event that abated with routine management may be considered for antiviral therapy.

Antiviral Therapy in HCV-Infected Decompensated Cirrhotics 7

Peginterferon-ribavirin combination therapy (table 3) is now considered the standard drug regimen in cases of HCV infection. In peginterferon, an inert polyethylene glycol moiety is inserted into the interferon molecule. This causes a decrease in renal clearance and thus an increase in the plasma half life (80 hrs) of the peginterferon molecule. Because of the prolonged half life, whereas the non-pegylated interferons need to be administered thrice weekly, pegylated interferons are administered once weekly. The two formulations of peginterferon currently available are peginterferon alpha-2a and 2b. They differ in the size and configuration of the polyethylene glycol moiety attached to the interferon molecule. Although the two peginterferon formulations have not yet been compared head-to-head in the published controlled trails, they are generally believed to be equivalent therapies and

180 μg SQ once weekly regardless of the weight

*Genotype 1*: Higher weight-adjusted dosage has shown better response rates (1000mg if 75kg∆ orally in two divided doses;

*Genotype 2&3*: Higher dosage has not been shown in published studies to be consistently associated with better response rates. Therefore, 800mg/day orally in two divided doses is the current dosage of choice regardless of the weight.⌂

1.5 μg/kg SQ once weekly

1200mg if >75kg)∞.

† Peginterferons are therapeutically superior to non-pegylated interferons.

assays, different treatment responses have been defined (table 4).

as well as non-pegylated interferon-ribavirin combination therapy.

ribavirin in patient's 75kg weight are comparable.

>800mg of ribavirin dose in genotypes 2 & 3 cases.

Abbreviations: kD, kilodaltons; μg, micrograms; SQ, subcutaneously; kg, kilograms; mg, milligrams.

∂ Peginterferon-ribavirin combination therapy is therapeutically superior to peginterferon monotherapy

∆ More studies are needed to ascertain whether or not the treatment outcomes with 1000mg and 800mg

∞ It is not yet clear whether or not patients heavier than 88 kg will have better outcomes on 1400mg of

⌂ More studies are needed to ascertain that whether or not heavier patients yield better results with

Table 3. Peginterferon-Ribavirin Combination Dosage Regimen: The Current Standard

After starting antiviral therapy, HCV RNA assay needs to be repeated at specific intervals to determine the treatment responses. Depending upon the results of the repeat HCV RNA

thus can be used interchangeably.

**Peginterferon alfa-2a** 

(Inj Pegasys 180 μg)

**Peginterferon alfa-2b** 

50/80/100/120/180 μg)

**(40 kD)†**

**(12 kD)**  (Inj Peg-Intron

Ribavirin<sup>∂</sup>

ribavirin than 1200mg.

**Drug: Recommended Dosage:** 



Table 1. Child–Pugh Score


Table 1.a Interpretation of Child–Pugh Score

MELD = 3.78[Ln serum bilirubin (mg/dL)] + 11.2[Ln INR] + 9.57[Ln serum creatinine (mg/dL)] + 6.43

#### **NB:**


#### Ln = natural logarithm

Table 2. MELD Score (Model For End-Stage Liver Disease) (12 and older):


Table 2.a Interpretation MELD Score

2. Whether or not to institute antiviral therapy in Child–Pugh class B patients should be individualized on case-to-case basis giving due consideration to factors like genotype (2 & 3 better than 1) & pre-treatment viral loads (< 800,000 IU/mL better than higher loads). In all such cases, antiviral therapy probably should be discontinued after 4 or 12

3. Patients with Child–Pugh class C (CTP score ≥10 or MELD score 18 [table 2]) disease are

**Points Class One year survival Two year survival** 

MELD = 3.78[Ln serum bilirubin (mg/dL)] + 11.2[Ln INR] + 9.57[Ln serum creatinine

1. If the patient has had dialysis at least twice in the past week, then the value for serum

2. Any value less than one is given a value of 1 (i.e. if bilirubin is 0.8, a value of 1.0 is used). This helps prevent the occurrence of scores below 0 (the natural logarithm of 1

MELD Score: 3 month mortality:

is 0, and any value below 1 would yield a negative result).

Table 2. MELD Score (Model For End-Stage Liver Disease) (12 and older):

≥40 71.3% 30–39 52.6% 20–29 19.6% 10–19 6.0% ≤9 1.9%

5-6 A 100% 85% 7-9 B 81% 57% 10-15 C 45% 35%

not considered appropriate candidates to institute antiviral therapy.

**Measure 1 point 2 points 3 points**  Total bilirubin, μmol/l (mg/dl) <34 (<2) 34-50 (2-3) >50 (>3) Serum albumin, g/l >35 28-35 <28 INR <1.7 1.71-2.20 > 2.20 Ascites None Mild Severe Hepatic encephalopathy None Grade I-II Grade III-IV

weeks if there is no virological response.

Table 1. Child–Pugh Score

(mg/dL)] + 6.43

Ln = natural logarithm

**NB:** 

Table 1.a Interpretation of Child–Pugh Score

creatinine used should be 4.0

Table 2.a Interpretation MELD Score

Peginterferon-ribavirin combination therapy (table 3) is now considered the standard drug regimen in cases of HCV infection. In peginterferon, an inert polyethylene glycol moiety is inserted into the interferon molecule. This causes a decrease in renal clearance and thus an increase in the plasma half life (80 hrs) of the peginterferon molecule. Because of the prolonged half life, whereas the non-pegylated interferons need to be administered thrice weekly, pegylated interferons are administered once weekly. The two formulations of peginterferon currently available are peginterferon alpha-2a and 2b. They differ in the size and configuration of the polyethylene glycol moiety attached to the interferon molecule. Although the two peginterferon formulations have not yet been compared head-to-head in the published controlled trails, they are generally believed to be equivalent therapies and thus can be used interchangeably.


Abbreviations: kD, kilodaltons; μg, micrograms; SQ, subcutaneously; kg, kilograms; mg, milligrams. † Peginterferons are therapeutically superior to non-pegylated interferons.

∂ Peginterferon-ribavirin combination therapy is therapeutically superior to peginterferon monotherapy as well as non-pegylated interferon-ribavirin combination therapy.

∆ More studies are needed to ascertain whether or not the treatment outcomes with 1000mg and 800mg ribavirin in patient's 75kg weight are comparable.

∞ It is not yet clear whether or not patients heavier than 88 kg will have better outcomes on 1400mg of ribavirin than 1200mg.

⌂ More studies are needed to ascertain that whether or not heavier patients yield better results with >800mg of ribavirin dose in genotypes 2 & 3 cases.

Table 3. Peginterferon-Ribavirin Combination Dosage Regimen: The Current Standard

After starting antiviral therapy, HCV RNA assay needs to be repeated at specific intervals to determine the treatment responses. Depending upon the results of the repeat HCV RNA assays, different treatment responses have been defined (table 4).

Antiviral Therapy in HCV-Infected Decompensated Cirrhotics 9

Shorten the standard treatment course of 24 weeks to 12- 16 weeks. Ribavirin is given at higher weight-adjusted dosage in the short courses (1000mg if 75 kg orally in

Successful therapy. Needs a repeat qualitative HCV RNA assay at week 48 (24 weeks after ETR) to establish SVR

*Previously treated with non-pegylated interferon:*  Treat with peginterferon and ribavirin. If EVR is not

Retreatment is not indicated even if a different type of peginterferon is administered. Consensus interferon has shown to improve responses in such cases, but it is too

achieved at week 12, stop the treatment *Previously treated with pegylated interferon:* 

two divided doses; 1200mg if >75 kg)‡,<sup>∂</sup>

**HCV RNA Assay: Recommendations according to the PCR results:** 

Positive assay Give treatment for the standard duration of 24 weeks<sup>∆</sup> (may be 36-48 weeks)

HCV infection eradicated

premature to recommend it.

† The newly recommended week 4 qualitative HCV RNA assay helps modify the duration of the therapy based on viral kinetics. On one hand, this approach helps maximize the SVR rates and on the other hand, limits the toxicities and cost associated with the extended treatment courses. Achievement

‡ With the shortened treatment courses in subjects who show RVR, SVR rates of 80-100% have been

Table 5. Summary of Current Standards in the Management of Genotypes 2&3 Cases:

∆ SVR rates achieved in this subgroup are poor, particularly in genotype 3 cases – 41-58%. In genotype 2 cases, the results are relatively better - 50-89%. Because of the poor SVR rates, prolonged therapy (>24 weeks) may be considered in this subgroup, although more evidence is needed at this time for a definite

∂ In case of relapse, retreatment with the standard 24 weeks course is recommended.

of RVR means that we can consider shortening the treatment course.

reported in genotype 2 cases and 77-85% in genotype 3 cases.

**Week 4 qualitative HCV RNA assay:†**

**Week 24 qualitative HCV RNA assay:** 

**Week 48 qualitative HCV RNA assay:** 

Positive assay Treatment failed

Negative assay (<50IU/mL)

Negative assay i.e. a case of

Negative assay i.e. a case of

Positive assay i.e. a case of

i.e. a case of RVR

ETR

SVR

relapse

recommendation.


\*Achievement of SVR is generally considered as the marker of eradication of HCV infection. Almost all such patients show EVC or PVR on 12 weeks assay.

Table 4. Definitions of Treatment Responses

Positive and negative predictors of therapeutic response:


The exact treatment protocol instituted in a given patient depends upon the genotype. Genotypes 2&3 are more responsive to interferon therapy than genotype 1 and therefore the recommended duration of antiviral therapy in former is 06 months as compared to one year in the latter. Although more data and experience is needed to establish definite protocols in genotypes 4, 5 & 6 cases, current evidence suggests treating them as genotype 1 cases.23 Tables 5 & 6 summarize the current standards of treatment depending upon the genotype.

#### **HCV RNA Assay: Recommendations according to the PCR results:**

#### **Week 4 qualitative HCV RNA assay:†**

8 Antiviral Drugs – Aspects of Clinical Use and Recent Advances

Quantitative HCV RNA assay done at 12 weeks:

**Nonresponders** Quantitative HCV RNA assay done at 12 weeks showing either no

(EVC) or aviremic response

(PVR) or viremic response

assay) or a decline of < 2 log

negative

such patients show EVC or PVR on 12 weeks assay. Table 4. Definitions of Treatment Responses

IU/mL) are other positive predictors.

Positive and negative predictors of therapeutic response:

negative (<50IU/mL)

Qualitative HCV RNA assay done at 4 weeks comes back to be

Comes back to be negative – called early virologic clearance

 Shows a decline in the HCV RNA titre (compared with the pretreatment assay) of ≥ 2 log – called partial virologic response

decline in the HCV RNA titre (compared with the pre-treatment

duration of the treatment course comes back to be negative

weeks later it becomes positive again (SVR not achieved). .

**Relapsers** Qualitative HCV RNA assay done on completion of the recommended

\*Achievement of SVR is generally considered as the marker of eradication of HCV infection. Almost all

1. *Positive predictors:* As otherwise, attainment of a rapid/ early virological response and genotypes 2 & 3 are the most robust predictors of viral clearance with antiviral therapy.10,12 Child–Pugh class A and lower pre-transplantation viral loads (< 800,000

2. *Negative predictors:* A reduction in the viral load of ≤2 l log10 between baseline & week 4, Child–Pugh class C or MELD >18 have a strong negative predictive value. In the absence of a ≥2 log10 reduction in HCV RNA at week 4, probably the best approach to

The exact treatment protocol instituted in a given patient depends upon the genotype. Genotypes 2&3 are more responsive to interferon therapy than genotype 1 and therefore the recommended duration of antiviral therapy in former is 06 months as compared to one year in the latter. Although more data and experience is needed to establish definite protocols in genotypes 4, 5 & 6 cases, current evidence suggests treating them as genotype 1 cases.23 Tables 5 & 6 summarize the current standards of treatment depending upon the

reduce the risk of complications is to stop antiviral therapy at this point.

Qualitative HCV RNA assay done on completion of the recommended

Qualitative HCV RNA assay done 24 weeks after completion of the recommended duration of the treatment course comes back to be

duration of the treatment course was negative (ETR achieved), but 24

**Rapid virologic response (RVR)** 

**Early virologic response (EVR)** 

**End of treatment response (ETR)** 

**Sustained virologic response (SVR)\*** 

genotype.


#### **Week 24 qualitative HCV RNA assay:**


#### **Week 48 qualitative HCV RNA assay:**


† The newly recommended week 4 qualitative HCV RNA assay helps modify the duration of the therapy based on viral kinetics. On one hand, this approach helps maximize the SVR rates and on the other hand, limits the toxicities and cost associated with the extended treatment courses. Achievement of RVR means that we can consider shortening the treatment course.

‡ With the shortened treatment courses in subjects who show RVR, SVR rates of 80-100% have been reported in genotype 2 cases and 77-85% in genotype 3 cases.

∂ In case of relapse, retreatment with the standard 24 weeks course is recommended.

∆ SVR rates achieved in this subgroup are poor, particularly in genotype 3 cases – 41-58%. In genotype 2 cases, the results are relatively better - 50-89%. Because of the poor SVR rates, prolonged therapy (>24 weeks) may be considered in this subgroup, although more evidence is needed at this time for a definite recommendation.

Table 5. Summary of Current Standards in the Management of Genotypes 2&3 Cases:

Antiviral Therapy in HCV-Infected Decompensated Cirrhotics 11

Monitoring the antiviral therapy not only involves asking repeat HCV RNA assays at specific intervals to determine therapeutic response, but also a battery of other blood tests to

*Week 4:* Qualitative HCV RNA assay at week 4 in both genotype 1 and 2&3 cases to

Pregnancy assay in a sexually-active female of child bearing age

*Week 12:* Quantitative HCV RNA test at week 12 in genotype 1 cases only to assess for

*Week 24:*  Qualitative HCV RNA assay at week 24 in only those genotype 1 cases

*Week 48*  Qualitative HCV RNA assay at week 48 in genotype 2&3 cases to determine

*Week 72*  Qualitative HCV RNA assay at week 72 in genotype 1 cases to determine

As a general rule, decompensated cirrhotics are more prone to develop drug-induced sideeffects compared to patients with compensated disease. Important side effects in

1. Drug-induced hematological side effects: neutropenia (50–60%), thrombocytopenia (30–

2. Superadded infections: spontaneous bacterial peritonitis (SBP), spontaneous bacteraemia/ septicaemia/ septic shock (due to Gram-negative bacilli) etc (4–13%).

The minimum effective dose of ribavirin appears to be 10.6 mg/kg/day. In case hemolytic anemia develops, it is recommended to first reduce the dose of ribavirin to the minimum

Qualitative HCV RNA assay at week 24 in genotype 2&3 cases to

Qualitative HCV RNA assay at week 48 in genotype 1 cases to determine

LFTs, INR, albumin, creatinine, urinalysis, glucose and TSH

rule out the development of any adverse effects (see table 7).

who attained EVR at week 12

determine ETR

SVR

ETR

SVR

Table 7. Monitoring of Anti-viral Therapy

**4. Pharmacotherapy of side effects**

50%), hemolytic anemia (30–50%).

**4.1 Drug-induced hematological side effects 4.1.1 Ribavirin-induced hemolytic anemia** 

3. Worsening of hepatic decompensation with therapy (11–20%).

decompensated cirrhotics include:16

*Fortnightly:* CBC at weeks 1, 2, 4, 6, 8 and then monthly

assess for RVR

EVR

*Every month:* 

*Every 3 months:* 


† Old age (>50yrs); male gender; African American race; obesity; alcoholism; HIV confection or immunosuppression; more-than-portal fibrosis on liver biopsy (Metavir ≥2 or Ishak ≥ 3); a pretreatment viral load of >800,000IU/mL.

‡ SVR rates of 80-89% can be achieved in this subgroup.

∂ In case of relapse, retreatment with the standard 48 weeks course is recommended.

Table 6. Summary of Current Standards in the Management of Genotype 1 Cases

*Predictors of poor response absent:*†

*Predictors of poor response present:* 

Continue treatment for a total of 48 weeks

Positive assay Continue treatment and repeat HCV RNA at 12 weeks

Shorten the treatment duration to a total of 24 weeks‡,<sup>∂</sup>

Give treatment for the standard duration of 48 weeks

Continue treatment & repeat qualitative HCV RNA at 24

Continue treatment for a total of 48-72 weeks. 72 weeks therapy has generally shown superior results as compared to 48 weeks therapy in slow responders.

Successful therapy. Needs a repeat qualitative HCV RNA assay at week 72 (24 weeks after ETR) to establish

*Previously treated with non-pegylated interferon:*  Treat with peginterferon and ribavirin. If EVR is not

Retreatment is not indicated even if a different type of peginterferon is administered. Consensus interferon has shown to improve responses in such cases, but it is too

achieved at week 12, stop the treatment *Previously treated with pegylated interferon:* 

**HCV RNA Assay: Recommendations as per the PCR results:** 

weeks.

Stop treatment

Positive assay Stop treatment as probability of attaining SVR is negligible

HCV infection got eradicated

premature to recommend it.

† Old age (>50yrs); male gender; African American race; obesity; alcoholism; HIV confection or immunosuppression; more-than-portal fibrosis on liver biopsy (Metavir ≥2 or Ishak ≥ 3); a pretreatment

∂ In case of relapse, retreatment with the standard 48 weeks course is recommended.

Table 6. Summary of Current Standards in the Management of Genotype 1 Cases

SVR

**Week 4 qualitative HCV RNA assay:** 

**Week 12 qualitative HCV RNA assay:** 

**Week 24 qualitative HCV RNA assay** 

**Week 48 qualitative HCV RNA assay:** 

**Week 72 qualitative HCV RNA assay:** 

Positive assay Treatment failed

‡ SVR rates of 80-89% can be achieved in this subgroup.

Negative assay i.e. a case of

Negative assay i.e. a case of

Positive assay i.e. a case of

viral load of >800,000IU/mL.

**(only done in cases which show PVR at week 12 assay):** 

Negative assay (<50IU/mL)

Negative assay i.e. a case of

HCV RNA fall by ≥ 2 logs i.e.

HCV RNA fall by < 2 logs i.e. a case of non-responder

i.e. a case of RVR

EVC

a case of PVR

responders')

ETR

SVR

relapse

Negative assay (this subgroup is called 'slow Monitoring the antiviral therapy not only involves asking repeat HCV RNA assays at specific intervals to determine therapeutic response, but also a battery of other blood tests to rule out the development of any adverse effects (see table 7).


Table 7. Monitoring of Anti-viral Therapy

#### **4. Pharmacotherapy of side effects**

As a general rule, decompensated cirrhotics are more prone to develop drug-induced sideeffects compared to patients with compensated disease. Important side effects in decompensated cirrhotics include:16


#### **4.1 Drug-induced hematological side effects**

#### **4.1.1 Ribavirin-induced hemolytic anemia**

The minimum effective dose of ribavirin appears to be 10.6 mg/kg/day. In case hemolytic anemia develops, it is recommended to first reduce the dose of ribavirin to the minimum

Antiviral Therapy in HCV-Infected Decompensated Cirrhotics 13

Dosage regimens: 3. 30MU subcutaneously once weekly and then adjusting the

**Monitoring G-CSF therapy:** Complete blood counts should be requested twice or thrice weekly and response to therapy judged. Once adequate neutrophil count is achieved, IFN dose can be *increased* to the optimum level.21 Once started, adjunct G-CSF therapy may be required till the end of the treatment. In one study,24 the median duration of G-CSF therapy

Norfloxacin prophylaxis has been shown to reduce the incidence of superadded infections.15,16 In cases of established nosocomial SBP (often caused by bacteria resistant to 3rd-generation cephalosporins and/or amoxicillin-clavulanic acid), broad-spectrum

Although it is not yet clear how much survival benefit antiviral therapy confers, a standardized mortality rate analysis in one study reported a lower liver-related mortality among cirrhotics with SVR (0.6: CI: 0.0-3.1) compared to untreated patients.29 In post-liver transplant cases, avoidance of allograft failure due to recurrence of HCV infection has also

One thing that has become increasingly clear from the existing trials data is that cirrhotic patients who are treated with antiviral therapy and who achieve SVR are less likely to develop liver-related complications as compared to the non-responders. Despite the many encouraging studies on this subject, data on the long-term disease progression, avoidance of transplantation, and most importantly, improvement of life expectancy is however still sparse. Although liver functions have clearly been shown to improve with antiviral therapy (as indicated by significant reductions in CTP and MELD scores), the same are more likely to deteriorate within a few years in patients with advanced cirrhosis thus explaining the need to accumulate data on the possible survival benefit conferred by antiviral therapy in

[1] Fattovich G, Giustina G, Degos F, Diodati G, Tremolada F, Nevens F, et al. Effectiveness

of interferon alfa on incidence of hepatocellular carcinoma and decompensation in

been reported in the literature although it needs further studies and validation.30

dose as per the response/ requirement.

2. Platelet count <30x109/L

Possible indications: 1. Neutrophil count <0.5x109/L.

Table 9. Granulocyte-colony-stimulating-factor (G-CSF) therapy

antibiotics like carbapenems or glycopeptides should be prescribed.

**4.2 Pharmacotherapy of superadded infections** 

was 20 weeks (range 9–45).

**5. Conclusion** 

cirrhotic patients.

**6. References** 

effective level. If no or little improvement in hemoglobin (Hb) level occurs, initiating concomitant erythropoietin (EPO) therapy may be considered.17,18


Table 8. Erythropoietin (EPO) therapy

**Monitoring EPO therapy:** The first evidence of response to the thrice weekly EPO administration is an increase in the reticulocyte count within 10 days.25 Since erythroid progenitors take several days to mature, a clinically significant increase in hematocrit is usually not observed in less than 2 weeks and may require up to 6 weeks in some patients.26 If the rate of rise of hemoglobin is greater than 1 g/dL over 2 weeks, it generally warrants decreasing EPO dose. This is because a greater than 1 g/dL rise in *any* 2 weeks during the course of the therapy has been associated with an increased risk of thromboembolic phenomenon, predisposing to myocardial infarction, stoke and even death.27 Also, according to manufacturer's recommendations, a Hb level of greater than 12g/dL should not be aimed, the reason being potentially increased risk of thromboembolic phenomenon.28 Once adequate Hb level (≥10g/dL) is achieved, ribavirin dose can be increased to the optimum level.20 Once started, adjunct EPO therapy may be required until the end of the treatment. In one study,24 the median duration of EPO treatment was 24 weeks (range 6–39).

#### **4.1.2 Interferon-induced neutropenia/ thrombocytopenia**

The minimum effective dose of pegylated interferon appears to be 1 μg/kg/wk. It is recommended to reduce IFN dose to the minimum effective level if neutrophil count falls to <0.5x109/L, and discontinue it if it falls to <0.3x109/L.17 Regarding platelet count, IFN dose should be reduced to the minimum effective level if platelet count falls to <30x109/L, and discontinued if it falls to <20x109/L.17 If no or little improvement in neutrophil/ platelet counts occur, initiating concomitant granulocyte-colony-stimulating-factor (G-CSF) or granulocyte-monocyte-colony-stimulating-factor (GM-CSF) therapy may be considered19,20 with an aim to avoid using the suboptimal drug doses.


Table 9. Granulocyte-colony-stimulating-factor (G-CSF) therapy

**Monitoring G-CSF therapy:** Complete blood counts should be requested twice or thrice weekly and response to therapy judged. Once adequate neutrophil count is achieved, IFN dose can be *increased* to the optimum level.21 Once started, adjunct G-CSF therapy may be required till the end of the treatment. In one study,24 the median duration of G-CSF therapy was 20 weeks (range 9–45).

#### **4.2 Pharmacotherapy of superadded infections**

Norfloxacin prophylaxis has been shown to reduce the incidence of superadded infections.15,16 In cases of established nosocomial SBP (often caused by bacteria resistant to 3rd-generation cephalosporins and/or amoxicillin-clavulanic acid), broad-spectrum antibiotics like carbapenems or glycopeptides should be prescribed.

Although it is not yet clear how much survival benefit antiviral therapy confers, a standardized mortality rate analysis in one study reported a lower liver-related mortality among cirrhotics with SVR (0.6: CI: 0.0-3.1) compared to untreated patients.29 In post-liver transplant cases, avoidance of allograft failure due to recurrence of HCV infection has also been reported in the literature although it needs further studies and validation.30

#### **5. Conclusion**

12 Antiviral Drugs – Aspects of Clinical Use and Recent Advances

effective level. If no or little improvement in hemoglobin (Hb) level occurs, initiating

Dosage regimens: 1. 20,000-40,000IU/week given in three divided doses

**Monitoring EPO therapy:** The first evidence of response to the thrice weekly EPO administration is an increase in the reticulocyte count within 10 days.25 Since erythroid progenitors take several days to mature, a clinically significant increase in hematocrit is usually not observed in less than 2 weeks and may require up to 6 weeks in some patients.26 If the rate of rise of hemoglobin is greater than 1 g/dL over 2 weeks, it generally warrants decreasing EPO dose. This is because a greater than 1 g/dL rise in *any* 2 weeks during the course of the therapy has been associated with an increased risk of thromboembolic phenomenon, predisposing to myocardial infarction, stoke and even death.27 Also, according to manufacturer's recommendations, a Hb level of greater than 12g/dL should not be aimed, the reason being potentially increased risk of thromboembolic phenomenon.28 Once adequate Hb level (≥10g/dL) is achieved, ribavirin dose can be increased to the optimum level.20 Once started, adjunct EPO therapy may be required until the end of the treatment. In one study,24 the median duration of EPO

The minimum effective dose of pegylated interferon appears to be 1 μg/kg/wk. It is recommended to reduce IFN dose to the minimum effective level if neutrophil count falls to <0.5x109/L, and discontinue it if it falls to <0.3x109/L.17 Regarding platelet count, IFN dose should be reduced to the minimum effective level if platelet count falls to <30x109/L, and discontinued if it falls to <20x109/L.17 If no or little improvement in neutrophil/ platelet counts occur, initiating concomitant granulocyte-colony-stimulating-factor (G-CSF) or granulocyte-monocyte-colony-stimulating-factor (GM-CSF) therapy may be considered19,20

3. Development of symptoms and signs attributable to anemia

subcutaneously (max. 60,000IU/week) with an aim to achieve & maintain Hb level of ≥10g/dL (return to the pretreatment

2. Another study suggested starting EPO therapy at a lower dose of 4,000IU subcutaneously thrice weekly (12,000IU/week) and

then increasing the dose depending upon the response.24

(palpitations, dyspnea, easy fatigability, pallor).21,22

concomitant erythropoietin (EPO) therapy may be considered.17,18

2. Hb levels of <8g/dL.

level is NOT the aim).23

Possible indications: 1. Fall in Hb level by >4 g/dL.

Table 8. Erythropoietin (EPO) therapy

treatment was 24 weeks (range 6–39).

**4.1.2 Interferon-induced neutropenia/ thrombocytopenia** 

with an aim to avoid using the suboptimal drug doses.

One thing that has become increasingly clear from the existing trials data is that cirrhotic patients who are treated with antiviral therapy and who achieve SVR are less likely to develop liver-related complications as compared to the non-responders. Despite the many encouraging studies on this subject, data on the long-term disease progression, avoidance of transplantation, and most importantly, improvement of life expectancy is however still sparse. Although liver functions have clearly been shown to improve with antiviral therapy (as indicated by significant reductions in CTP and MELD scores), the same are more likely to deteriorate within a few years in patients with advanced cirrhosis thus explaining the need to accumulate data on the possible survival benefit conferred by antiviral therapy in cirrhotic patients.

#### **6. References**

[1] Fattovich G, Giustina G, Degos F, Diodati G, Tremolada F, Nevens F, et al. Effectiveness of interferon alfa on incidence of hepatocellular carcinoma and decompensation in

Antiviral Therapy in HCV-Infected Decompensated Cirrhotics 15

[16] Bruno Roche, Didier Samuel. Antiviral therapy in HCV-infected cirrhotics awaiting

[17] Kasper C. Recombinant human erythropoietin in the treatment of anemic patients with

[18] Itri LM. The use of epoetin alfa in chemotherapy patients: a consistent profile of efficacy

[19] Hubel K, Dale DC, Liles WC. Therapeutic use of cytokines to modulate phagocyte

[20] Berghmans T, Paesmans M, Lafitte JJ, Mascaux C, Meert AP, Jacquy C, et al.

[21] Danish FA, Koul SS, Subhani FR, Rabbani AE, Yasmin S. Role of haematopoietic growth

[22] Afdhal NH, Dieterich DT, Pockros PJ, Schiff ER, Shiffman ML, Sulkowski MS, et al.

[23] M Sherman, S Shafran, K Burak. Management of chronic hepatitis C: Consensus

[24] Lebray P, Nalpas B, Vallet-Pichard A. The impact of haematopoietic growth factors on

[25] Eschbach JW, Egrie JC, Downing MR, et al. Correction of the Anemia of End-

[26] Eschbach JW, Abdulhadi MH, Browne JK. Recombinant Human Erythropoietin in

[27] Singh AK, Szczech L, Tang KL. Correction of Anemia with Epoetin Alfa in Chronic

[28] Besarab A, Bolton WK, Browne JK. The effects of normal as compared with low

[29] Yoshida H, Arakawa Y, Sata M, Nishiguchi S, Yano M, Fujiyama S, Yamada G, et al.

hematological malignancies. Ann Hematol 2001;80:319–329.

with meta-analysis. Support Care Cancer 2002;10:181–188.

guidelines. Can J Gastroenterol 2007 ;21(Suppl C):25C-34C.

Kidney Disease, N Engl j Med. 2006; 355:2085-98.

haemodialysis and epoetin. NEJM. 1998;339:584-90.

and safety. Semin Oncol 2002;29(suppl 8):81–87.

2009;50 (4): 652-654.

2002;185:1490–1501.

Gastroenterol 2008;14:151-7.

Gastroenterology 2004; 126:1302–1311.

virus. Antivir Ther 2005;10:769-76.

Gastroenterology 2002; 123: 483-491

1987;316:73-78.

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liver transplantation: A costly strategy for mixed virological results. J Hepatol.

function for the treatment of infectious diseases: current status of granulocyte colony-stimulating factor, granulocyte-macrophage colony stimulating factor, macrophage colony-stimulating factor, and interferon gamma. J Infect Dis

Therapeutic use of granulocyte and granulocyte-macrophage colony-stimulating factors in febrile neutropenic cancer patients. A systematic review of the literature

factors as adjuncts in the treatment of chronic hepatitis C patients. Saudi J

Proactive Study Group. Epoetin alfa maintains ribavirin dose in HCV-infected patients: a prospective, double-blind, randomized controlled study.

the management and efficacy of antiviral treatment in patients with hepatitis C

Stage Renal Disease with Recombinant Human Erythropoietin. NEJM.

Anemic Patients with End-Stage Renal Disease. Ann Intern Med. 1989;111:992-

haematocrit values in patients with cardiac disease who are receiving

Interferon therapy prolonged life expectancy among chronic hepatitis C patients.

cirrhosis type C. European Concerted Action on Viral Hepatitis (EUROHEP). J Hepatol 1997; 27: 201-205


[2] Terrault NA, Berenguer M. Treating hepatitis C infection in liver transplant recipients.

[3] Everson GT, Trouillot T, Trotter J, Skilbred J, Halprin A, McKinley C, et al. Treatment of

[4] Everson GT, Trotter J, Forman L. Treatment of advanced hepatitis C with a lowaccelerating dosage regimen of antiviral therapy. Hepatology 2005;42:255-62. [5] Everson GT. Treatment of chronic hepatitis C in patients with decompensated cirrhosis.

[6] Everson GT. Treatment of patients with hepatitis C on the waiting list. Liver Transpl

[7] Crippin JS, McCashland T, Terrault N, Sheiner P, Charlton MR. A pilot study of the

[8] Heathcote EJ, Shiffman ML, Cooksley WG, Dusheiko GM, Lee SS, Balart L, et al.

[9] Hoofnagle JH, Di Bisceglie AM, Waggoner JG, Park Y. Interferon alfa for patients with

[10] Iacobellis A, Siciliano M, Perri F, Annicchiarico BE, Leandro G, Caruso N, et al.

decompensated cirrhosis: a controlled study. J Hepatol 2007; 46: 206-212 [11] Thomas RM, Brems JJ, Guzman-Hartman G, Yong S, Cavaliere P, Van Thiel DH.

interferon therapy before transplantation. Liver Transpl 2003; 9: 905-915 [12] Di Marco V, Almasio PL, Ferraro D, Calvaruso V, Alaimo G, Peralta S, et al. Peg-

hypertension: a randomized controlled trial. J Hepatol 2007; 47: 484-491 [13] Angelo Iacobellis, Antonio Ippolito, Angelo Andriulli. Antiviral therapy in hepatitis C

[14] Tekin F, Gunsar F, Karasu Z, Akarca U, Ersoz G. Safety, tolerability, and efficacy of

[15] Carrión JA, Martínez-Bauer E, Crespo G, Ramírez S, Pérez-del-Pulgar S, García-

cirrhotics. Aliment Pharmacol Ther. 2008 Jun 1;27(11):1081-5.

awaiting liver transplantation. Liver Transpl 2002; 8:350–355.

tolerability and efficacy of antiviral therapy in hepatitis C virus-infected patients

Peginterferon alfa-2a in patients with chronic hepatitis C and cirrhosis. N Engl J

clinically apparent cirrhosis due to chronic hepatitis B. Gastroenterology

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interferon alone or combined with ribavirin in HCV cirrhosis with portal

virus cirrhotic patients in compensated and decompensated condition. World J

pegylated-interferon alfa-2a plus ribavirin in HCV-related decompensated

Valdecasas JC, et al. Antiviral therapy increases the risk of bacterial infections in HCV-infected cirrhotic patients awaiting liver transplantation: A retrospective

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decompensated cirrhotics with a low-accelerating dose regimen (LADR) of interferon-alfa-2b plus ribavirin: safety and efficacy [Abstract]. HEPATOLOGY


**2** 

*Germany* 

**Virus Diagnostics and Antiviral Therapy** 

*2Department for Ophthalmology, Christian Albrecht University of Kiel and* 

Acute retinal necrosis (ARN) is a fulminant necrotizing form of retinitis of viral origin. Without treatment, ARN leads to the irreversible blindness by destruction of the retina and the optic nerve. The clinical observation was first described under the term *Kirisawa uveitis* (Urayama et al., 1971) while the term *acute retinal necrosis* was introduced by Young & Bird (1978). The international diagnostic standard criteria were defined by Holland et al. (1994). ARN is a rare disease occurring world-wide in approximately one per 1.5-2.0 million persons per year (Muthiah et al., 2007; Vandercam et al., 2008). The rareness of this disease precludes randomized prospective clinical studies. Most observations are derived from small case series and homogenous international guidelines for therapy are still lacking. A few stu-

dies, however, allow statements on the causative agents and therapeutic principles.

slightly more frequently than women (Rautenberg et al., 2009).

Initially, herpesvirus particles were detected by electron microscopy in the retina of enucleated eyes with ARN. The causative role of herpesviruses was further established by showing local virus-specific antibody production, by demonstrating viral nucleic acids with the polymerase chain reaction (PCR), and by therapeutic success with antiviral drugs (Culbertson & Atherton, 1993). The disease is mainly caused by the -herpesviruses varicella-zoster virus (VZV) or herpes-simplex virus (HSV) in 70% and 30% of the cases, respectively (*e.g.,* Culbertson et al., 1986; Rummelt et al., 1992). While the -herpesvirus cytomegalovirus (CMV) plays a marginal role in the pathogenesis of ARN, the role of the -herpesvirus Epstein-Barr virus (EBV) remains controversial. Meta-analysis shows that men are affected

The early ARN diagnosis is primarily based on the virus-specific polymerase-chain reaction in punctuate fluid from the anterior chamber or the vitreous and can be supported by the detection of specific antibody titers from punctate fluid and serum using the Goldmann-Witmer coefficient. Detection of virus DNA provides the basis for the early antiviral therapy which limits disease progression and risk for complications. Retinal infections by VZV or HSV are treated with aciclovir, valaciclovir, or famciclovir. Ganciclovir and valganciclovir are primarily used for the therapy of retinal CMV infections. In the case of resistance

**1. Introduction** 

**in Acute Retinal Necrosis (ARN)** 

*University Medical Center Schleswig-Holstein, Kiel,* 

*1Institute for Infection Medicine,* 

Peter Rautenberg1, Jost Hillenkamp2, Livia Grančičova1, Bernhard Nölle2, Johann Roider2 and Helmut Fickenscher1\*

[30] Forns X, Garcia-Retortillo M, Serrano T, Feliu A, Suarez F, de la Mata M, et al. Antiviral therapy of patients with decompensated cirrhosis to prevent recurrence of hepatitis C after liver transplantation. J Hepatol 2003; 39: 389-396

## **Virus Diagnostics and Antiviral Therapy in Acute Retinal Necrosis (ARN)**

Peter Rautenberg1, Jost Hillenkamp2, Livia Grančičova1, Bernhard Nölle2, Johann Roider2 and Helmut Fickenscher1\* *1Institute for Infection Medicine, 2Department for Ophthalmology, Christian Albrecht University of Kiel and University Medical Center Schleswig-Holstein, Kiel, Germany* 

#### **1. Introduction**

16 Antiviral Drugs – Aspects of Clinical Use and Recent Advances

[30] Forns X, Garcia-Retortillo M, Serrano T, Feliu A, Suarez F, de la Mata M, et al. Antiviral

C after liver transplantation. J Hepatol 2003; 39: 389-396

therapy of patients with decompensated cirrhosis to prevent recurrence of hepatitis

Acute retinal necrosis (ARN) is a fulminant necrotizing form of retinitis of viral origin. Without treatment, ARN leads to the irreversible blindness by destruction of the retina and the optic nerve. The clinical observation was first described under the term *Kirisawa uveitis* (Urayama et al., 1971) while the term *acute retinal necrosis* was introduced by Young & Bird (1978). The international diagnostic standard criteria were defined by Holland et al. (1994). ARN is a rare disease occurring world-wide in approximately one per 1.5-2.0 million persons per year (Muthiah et al., 2007; Vandercam et al., 2008). The rareness of this disease precludes randomized prospective clinical studies. Most observations are derived from small case series and homogenous international guidelines for therapy are still lacking. A few studies, however, allow statements on the causative agents and therapeutic principles.

Initially, herpesvirus particles were detected by electron microscopy in the retina of enucleated eyes with ARN. The causative role of herpesviruses was further established by showing local virus-specific antibody production, by demonstrating viral nucleic acids with the polymerase chain reaction (PCR), and by therapeutic success with antiviral drugs (Culbertson & Atherton, 1993). The disease is mainly caused by the -herpesviruses varicella-zoster virus (VZV) or herpes-simplex virus (HSV) in 70% and 30% of the cases, respectively (*e.g.,* Culbertson et al., 1986; Rummelt et al., 1992). While the -herpesvirus cytomegalovirus (CMV) plays a marginal role in the pathogenesis of ARN, the role of the -herpesvirus Epstein-Barr virus (EBV) remains controversial. Meta-analysis shows that men are affected slightly more frequently than women (Rautenberg et al., 2009).

The early ARN diagnosis is primarily based on the virus-specific polymerase-chain reaction in punctuate fluid from the anterior chamber or the vitreous and can be supported by the detection of specific antibody titers from punctate fluid and serum using the Goldmann-Witmer coefficient. Detection of virus DNA provides the basis for the early antiviral therapy which limits disease progression and risk for complications. Retinal infections by VZV or HSV are treated with aciclovir, valaciclovir, or famciclovir. Ganciclovir and valganciclovir are primarily used for the therapy of retinal CMV infections. In the case of resistance

Virus Diagnostics and Antiviral Therapy in Acute Retinal Necrosis (ARN) 19

as detected by by PCR in trigeminal ganglia, 79% for VZV, 53% for HSV-1, and 7% for HSV-2, respectively (Pevenstein et al., 1999). Moreover, the HSV-specific latency-associated transcripts and HSV-reactive CD8+ T cells were clearly less frequent in the neurones projecting to the ophthalmic nerve as in the other branches of the trigeminal nerve (Hüfner et al., 2009). These findings indicate that HSV reactivations occur more rarely in the eye than in the other

As the latency site of CMV, hematopoetic myelomonocytic progenitor cells are considered, from which systemic dissemination occurs via monocytes (Crough et al., 2009; Sinclair, 2008; Sinclair & Sissons, 2006). EBV replicates primarily in the pharyngeal and tonsillar epithelium and in B cells. EBV latency is localized to quiescent B lymphocytes (Miyashita et al., 1995). Both viruses can be reactivated spontaneously or, drastically more frequently, during immunosuppression. Correspondingly, the simultaneous demonstration of DNA of differrent herpesviruses is possible in retinitis or ARN (Hasselbach et al., 2008; Hillenkamp et al.,

The mechanisms are not yet sufficiently clarified which lead to the viral infection of the retina and finally to ARN. In a murine model, retinitis of the contralateral eye was observed within three days after intravitreal inoculation with a highly neurovirulent HSV-1 strain (Labetoulle et al., 2000). The time course of virus spread and immunohistological findings support the theory of non-synaptic virus transfer between neurones and glia cells in the chiasma opticum leading to the infection of the contralateral eye (Labetoulle et al., 2000). This is clinically relevant, since specific antiviral therapy reduces the risk for bilateral ARN

For rare diseases such as herpesviral encephalitis or ARN, causative immunological defects have been discussed. In one study, plasmacytoid dendritic cells from nine ARN patients were significantly fewer than in healthy controls, as well as interferon- production and CD8+ cell responses were clearly diminished. This could contribute to the impaired control of latent herpesvirus infections and subsequent development of ARN (Kittan et al., 2007).

ARN is an extremely rare disease. Patients with endogenous uveitis had ARN in 1.3% (41 of 3060; 95% confidence interval [CI]: 0.97-1.83%; Goto et al., 2007). During a prospective study in Great Britain over a period of 12 months, an ARN incidence of 0.5-0.6 per million was determined (Muthiah et al., 2007). Retrospective results were obtained for the Netherlands with a similar incidence of 1.1-1.6 per million (Vandercam et al., 2008). Approximately 55% of ARN patients are men (Fig. 1; Rautenberg et al., 2009: ratio men/women: 1.18; 95% CI: 1.06- 1.29). In contrast, only 37.7% of the patients with orofacial herpes are men (95% CI: 33-43%; Lorette et al., 2006), while HSV seroprevalence is identical in both genders (Malkin et al., 2002). More than 97% (95% CI: 96-99%) of all ARN cases are caused by the -herpesviruses VZV, HSV-1, and HSV-2. VZV is the most common causative agent of ARN in approximately 70% (Fig. 2; Rautenberg et al., 2009; 95% CI: 66-76%) of ARN cases, followed by HSV-2 and HSV-1. The age of ARN manifestation depends on the causative agent. Patients with VZVinduced ARN were 48.8±19.6 years old (mean ±1 standard deviation; Fig. 3). The mean age of HSV-1- or HSV-2-induced ARN patients was 31.1±17.5 or was 47.8+-19.2 or 31.1+-17.5

orofacial regions.

(Palay et al., 1991).

**2.2 Epidemiology** 

years, respectively

2009a; Lau et al., 2007; Sugita et al., 2008).

development against antiviral drugs, foscarnet or cidofovir are available as second-line antiviral drugs. The early specific antiviral therapy is the crucial prerequisite for the optimal clinical outcome. The pros and cons of the different application routes (oral, intraveneous, intravitreal) are discussed in order to provide sufficient drug levels in the eye. The antiviral therapy of ARN must be combined with ophthalmological and surgical procedures. Early vitrectomy has been shown to lead to a significant reduction of secondary retinal detachment. The early and combined strategy is essential for the clinical outcome of the rare ARN (Hillenkamp et al., 2009a, b, 2010; Pleyer et al., 2009).

#### **2. Pathogenesis, epidemiology, and clinical course of ARN**

#### **2.1 Viral pathogenesis**

The establishment of latency after primary infection is a common feature of herpesviruses. During latency, the entire, mostly inactive virus genome is maintained in the nuclei of host cells. The -herpesviruses VZV, HSV-1, and HSV-2 are characterized by their tropism for sensory neurones and epithelia. Via mucosal or cutaneous entry sites, the neurotropic herpesviruses gain access to the peripheral endings of sensory neurones. After virus uptake and axonal transport of the nucleocapsids, the virus establishes latency within approximately 14 days in the nucleus of autonomous or sensory ganglia. The viral genome persists there in circular, extrachromosomal form (Steiner et al., 2007).

In case of HSV, production of latency-associated viral transcripts seems to block virus replication and neuronal cell death. HSV-1 was shown to induce a local, CD8+ T cell-mediated, non-lytical inflammation in human trigeminal ganglia (Mott et al., 2009; Theil et al., 2003). These CD8+ T cells seem to block HSV reactivation via release of granzyme B which selectively degrades one of the regulatory proteins of HSV-1 and inhibits reactivation already in the very early phase (Khanna et al., 2004; Knickelbein et al., 2008). Thus, a well balanced equilibrium between host defense and viral immune evasion mechanisms is formed during herpesviral latency. Since virus particles are not produced during latency, virus elimination by antiviral drugs is not feasible.

The factors are not well defined which induce the reactivation of herpesvirus replication and the axonal transport of the viral nucleocapsids from the ganglion to the periphery. For HSV, ultraviolet light, neurosurgical procedures, periocular trauma and high-dosed steroid medication are known to cause reactiviation. During peripheral virus replication, clinical symptoms are observed in the region innervated by the respective sensory nerve, mostly in the form of oroacial herpes or as herpes zoster (shingles) and by far more rarely as ocular herpes (Liesegang, 2001; Lorette et al., 2006; Malvy et al., 2007).

The extremely low incidence of the ocular herpes manifestations can be explained through epidemiology as well as neuroanatomy. HSV-1 and HSV-2 have strongly different capabilities of establishing latency in trigeminal or sacral sensory ganglia and of inducing reactivation. Whereas 41% of the cases with latent trigeminal HSV-1 reactivate the virus, this occurs only in 4% of the trigeminal HSV-2 infections. In latent sacral HSV-2 infections, 89% of the patients develop recurrent genital herpes, in contrast to 25% of the cases with sacral HSV-1 latency (Lafferty et al., 1987). The rate for the symptomatic recurrence of orofacial HSV-1 is 0.12 per month in contrast to 0.001 for orofacial HSV-2 (Lafferty et al., 1987). The different rates of reactivation from different anatomical regions correspond to the mRNA prevalence as detected by by PCR in trigeminal ganglia, 79% for VZV, 53% for HSV-1, and 7% for HSV-2, respectively (Pevenstein et al., 1999). Moreover, the HSV-specific latency-associated transcripts and HSV-reactive CD8+ T cells were clearly less frequent in the neurones projecting to the ophthalmic nerve as in the other branches of the trigeminal nerve (Hüfner et al., 2009). These findings indicate that HSV reactivations occur more rarely in the eye than in the other orofacial regions.

As the latency site of CMV, hematopoetic myelomonocytic progenitor cells are considered, from which systemic dissemination occurs via monocytes (Crough et al., 2009; Sinclair, 2008; Sinclair & Sissons, 2006). EBV replicates primarily in the pharyngeal and tonsillar epithelium and in B cells. EBV latency is localized to quiescent B lymphocytes (Miyashita et al., 1995). Both viruses can be reactivated spontaneously or, drastically more frequently, during immunosuppression. Correspondingly, the simultaneous demonstration of DNA of differrent herpesviruses is possible in retinitis or ARN (Hasselbach et al., 2008; Hillenkamp et al., 2009a; Lau et al., 2007; Sugita et al., 2008).

The mechanisms are not yet sufficiently clarified which lead to the viral infection of the retina and finally to ARN. In a murine model, retinitis of the contralateral eye was observed within three days after intravitreal inoculation with a highly neurovirulent HSV-1 strain (Labetoulle et al., 2000). The time course of virus spread and immunohistological findings support the theory of non-synaptic virus transfer between neurones and glia cells in the chiasma opticum leading to the infection of the contralateral eye (Labetoulle et al., 2000). This is clinically relevant, since specific antiviral therapy reduces the risk for bilateral ARN (Palay et al., 1991).

For rare diseases such as herpesviral encephalitis or ARN, causative immunological defects have been discussed. In one study, plasmacytoid dendritic cells from nine ARN patients were significantly fewer than in healthy controls, as well as interferon- production and CD8+ cell responses were clearly diminished. This could contribute to the impaired control of latent herpesvirus infections and subsequent development of ARN (Kittan et al., 2007).

#### **2.2 Epidemiology**

18 Antiviral Drugs – Aspects of Clinical Use and Recent Advances

development against antiviral drugs, foscarnet or cidofovir are available as second-line antiviral drugs. The early specific antiviral therapy is the crucial prerequisite for the optimal clinical outcome. The pros and cons of the different application routes (oral, intraveneous, intravitreal) are discussed in order to provide sufficient drug levels in the eye. The antiviral therapy of ARN must be combined with ophthalmological and surgical procedures. Early vitrectomy has been shown to lead to a significant reduction of secondary retinal detachment. The early and combined strategy is essential for the clinical outcome of the rare

The establishment of latency after primary infection is a common feature of herpesviruses. During latency, the entire, mostly inactive virus genome is maintained in the nuclei of host cells. The -herpesviruses VZV, HSV-1, and HSV-2 are characterized by their tropism for sensory neurones and epithelia. Via mucosal or cutaneous entry sites, the neurotropic herpesviruses gain access to the peripheral endings of sensory neurones. After virus uptake and axonal transport of the nucleocapsids, the virus establishes latency within approximately 14 days in the nucleus of autonomous or sensory ganglia. The viral genome persists there in

In case of HSV, production of latency-associated viral transcripts seems to block virus replication and neuronal cell death. HSV-1 was shown to induce a local, CD8+ T cell-mediated, non-lytical inflammation in human trigeminal ganglia (Mott et al., 2009; Theil et al., 2003). These CD8+ T cells seem to block HSV reactivation via release of granzyme B which selectively degrades one of the regulatory proteins of HSV-1 and inhibits reactivation already in the very early phase (Khanna et al., 2004; Knickelbein et al., 2008). Thus, a well balanced equilibrium between host defense and viral immune evasion mechanisms is formed during herpesviral latency. Since virus particles are not produced during latency, virus elimination

The factors are not well defined which induce the reactivation of herpesvirus replication and the axonal transport of the viral nucleocapsids from the ganglion to the periphery. For HSV, ultraviolet light, neurosurgical procedures, periocular trauma and high-dosed steroid medication are known to cause reactiviation. During peripheral virus replication, clinical symptoms are observed in the region innervated by the respective sensory nerve, mostly in the form of oroacial herpes or as herpes zoster (shingles) and by far more rarely as ocular herpes

The extremely low incidence of the ocular herpes manifestations can be explained through epidemiology as well as neuroanatomy. HSV-1 and HSV-2 have strongly different capabilities of establishing latency in trigeminal or sacral sensory ganglia and of inducing reactivation. Whereas 41% of the cases with latent trigeminal HSV-1 reactivate the virus, this occurs only in 4% of the trigeminal HSV-2 infections. In latent sacral HSV-2 infections, 89% of the patients develop recurrent genital herpes, in contrast to 25% of the cases with sacral HSV-1 latency (Lafferty et al., 1987). The rate for the symptomatic recurrence of orofacial HSV-1 is 0.12 per month in contrast to 0.001 for orofacial HSV-2 (Lafferty et al., 1987). The different rates of reactivation from different anatomical regions correspond to the mRNA prevalence

ARN (Hillenkamp et al., 2009a, b, 2010; Pleyer et al., 2009).

circular, extrachromosomal form (Steiner et al., 2007).

(Liesegang, 2001; Lorette et al., 2006; Malvy et al., 2007).

**2.1 Viral pathogenesis** 

by antiviral drugs is not feasible.

**2. Pathogenesis, epidemiology, and clinical course of ARN** 

ARN is an extremely rare disease. Patients with endogenous uveitis had ARN in 1.3% (41 of 3060; 95% confidence interval [CI]: 0.97-1.83%; Goto et al., 2007). During a prospective study in Great Britain over a period of 12 months, an ARN incidence of 0.5-0.6 per million was determined (Muthiah et al., 2007). Retrospective results were obtained for the Netherlands with a similar incidence of 1.1-1.6 per million (Vandercam et al., 2008). Approximately 55% of ARN patients are men (Fig. 1; Rautenberg et al., 2009: ratio men/women: 1.18; 95% CI: 1.06- 1.29). In contrast, only 37.7% of the patients with orofacial herpes are men (95% CI: 33-43%; Lorette et al., 2006), while HSV seroprevalence is identical in both genders (Malkin et al., 2002).

More than 97% (95% CI: 96-99%) of all ARN cases are caused by the -herpesviruses VZV, HSV-1, and HSV-2. VZV is the most common causative agent of ARN in approximately 70% (Fig. 2; Rautenberg et al., 2009; 95% CI: 66-76%) of ARN cases, followed by HSV-2 and HSV-1. The age of ARN manifestation depends on the causative agent. Patients with VZVinduced ARN were 48.8±19.6 years old (mean ±1 standard deviation; Fig. 3). The mean age of HSV-1- or HSV-2-induced ARN patients was 31.1±17.5 or was 47.8+-19.2 or 31.1+-17.5 years, respectively

Virus Diagnostics and Antiviral Therapy in Acute Retinal Necrosis (ARN) 21

(Ganatra et al., 2000; Itoh et al., 2000; Kychenthal et al., 2001; Rahhal et al., 1996; Schlingemann et al., 1996; Tran et al., 2003b; van Gelder et al., 2001). According to these results, a cut-off value of 36 years allows to discriminate HSV-2 from the other herpesviusinduced ARN (Fig. 3; sensitivity: 64%; specificity: 83%; positive predictive value at 30% prevalence: 56%; negative predictive value at 30% prevalence: 84%). The diagnostic discrimination between ARN caused by HSV-1, HSV-2, or VZV is not highly relevant, since

In contrast, the virological and clinical discrimination of CMV retinitis from ARN caused by the three -herpesviruses is very important, since the drug of choice is ganciclovir in CMV infections. CMV as the causative agent of a viral retinitis in absence of immunsuppressive therapy in immunocompetent patients is extremely rare. To our knowledge, only four such cases were documented in the literature (Silverstein et al., 1997; Tajunisah et al., 2009; Ura-

**HSV-1 HSV-2 VZV CMV** Fig. 3. Age-distribution of patients who contracted ARN by different herpesviruses. Analysis showed a significant younger age in patients who were infected by HSV-2 as compared

The controversial role of EBV for ARN was investigated in a case control study (Ongkosuwito et al., 1998). By qualitative PCR, EBV was detected in one out of 24 ocular ARN samples. However, three of 46 vitreous samples from a control group also contained EBV DNA (odds ratio: 0.62; 95% CI: 0.06-6.34). Therefore, an association between the demonstration of EBV DNA and ARN could not be determined. Only a few studies analysed EBV DNA prevalence in ARN (Abe et al., 1996; Hillenkamp et al., 2009a; Itoh et al., 2000; Lau et al., 2007; Ongkosuwito et al., 1998; Sugita et al., 2008; Tran et al., 2003a; Yamamoto et al., 2008). In nine of 134 ARN patients, EBV DNA was detected from ocular samples. In seven of these nine ARN patients (78%; 95% CI: 40-96%) VZV DNA was detected in addition to EBV by PCR (Hillenkamp et al., 2009a; Lau et al., 2007; Sugita et al., 2008). In theory, quantitative PCR methods could contribute to a clarification. However, there are no standard values for clinically relevant DNA concentrations in ocular materials and neither the diagnostic

to the other herpesviruses. The triangle within the box indicates the mean.

the therapy is identical in these cases, primarily by aciclovir.

yama et al., 1971; Voros et al., 2006).

**0**

**20**

**40**

**age (y)** **60**

**80**

Fig. 1. Gender distribution in ARN patients. The total value (diamond) indicates slightly more men than women (54% men vs. 46% women).

Fig. 2. Fraction of patients with VZV-induced ARN. The total value (diamond) indicates a favourite role of VZV (about 70%) in this rare disease.

author ratio men/women (95% CI)

1.00 (0.64-1,36) 0.45 (0.18-0.82) 1.11 (0.65-1.56) 0.83 (0.47-1.21) 1.86 (1.55-2.15) 2.44 (1.84-2.92) 0.93 (0.67-1.19) 1.45 (0.99-1.88) 0.81 (0.59-1.05) 1.18 (1.06-1.29)

76.9 (49.1-93.8) 70.5 (55.8-82.5) 50.0 (31.3-68.7) 56.3 (32.0-78.5) 50.0 (23.8-76.6) 62.5 (49.1-93.8) 52.6 (30.6-73.9) 61.1 (37.7-81.1) 83.8 (74.4-90.7) 73.2 (58.2-85.0) 78.8 (67.8-93.8) 70.1 (66.0-76.1)

Fig. 1. Gender distribution in ARN patients. The total value (diamond) indicates slightly

author fraction of VZV (95% CI)

0.1 0.2 0.5 12 3

ratio men/women with ARN

Fig. 2. Fraction of patients with VZV-induced ARN. The total value (diamond) indicates a

0 20 40 60 80 100 fraction of VZV in patients with ARN (%)

more men than women (54% men vs. 46% women).

Ganatra et al. 2000 Itoh et al. 2000 Tran etal. 2003 Lau et al. 2005 Goto et al. 2007 Muthia et al. 2007 Vanderkam et al. 2008 Hillenkamp et al. 2009 Tibbetts et al. 2010

total

de Boer et al. 1996 Ichikawa et al. 1997 Ganatra et al. 2000 Itoh et al. 2000 Tran et al. 2003 Lau et al. 2007 Muthia et al. 2007 Sugita et al. 2008 Usui et al. 2008 Vandercam et al.2008 Hillenkamp et al.2009

total

favourite role of VZV (about 70%) in this rare disease.

(Ganatra et al., 2000; Itoh et al., 2000; Kychenthal et al., 2001; Rahhal et al., 1996; Schlingemann et al., 1996; Tran et al., 2003b; van Gelder et al., 2001). According to these results, a cut-off value of 36 years allows to discriminate HSV-2 from the other herpesviusinduced ARN (Fig. 3; sensitivity: 64%; specificity: 83%; positive predictive value at 30% prevalence: 56%; negative predictive value at 30% prevalence: 84%). The diagnostic discrimination between ARN caused by HSV-1, HSV-2, or VZV is not highly relevant, since the therapy is identical in these cases, primarily by aciclovir.

In contrast, the virological and clinical discrimination of CMV retinitis from ARN caused by the three -herpesviruses is very important, since the drug of choice is ganciclovir in CMV infections. CMV as the causative agent of a viral retinitis in absence of immunsuppressive therapy in immunocompetent patients is extremely rare. To our knowledge, only four such cases were documented in the literature (Silverstein et al., 1997; Tajunisah et al., 2009; Urayama et al., 1971; Voros et al., 2006).

Fig. 3. Age-distribution of patients who contracted ARN by different herpesviruses. Analysis showed a significant younger age in patients who were infected by HSV-2 as compared to the other herpesviruses. The triangle within the box indicates the mean.

The controversial role of EBV for ARN was investigated in a case control study (Ongkosuwito et al., 1998). By qualitative PCR, EBV was detected in one out of 24 ocular ARN samples. However, three of 46 vitreous samples from a control group also contained EBV DNA (odds ratio: 0.62; 95% CI: 0.06-6.34). Therefore, an association between the demonstration of EBV DNA and ARN could not be determined. Only a few studies analysed EBV DNA prevalence in ARN (Abe et al., 1996; Hillenkamp et al., 2009a; Itoh et al., 2000; Lau et al., 2007; Ongkosuwito et al., 1998; Sugita et al., 2008; Tran et al., 2003a; Yamamoto et al., 2008). In nine of 134 ARN patients, EBV DNA was detected from ocular samples. In seven of these nine ARN patients (78%; 95% CI: 40-96%) VZV DNA was detected in addition to EBV by PCR (Hillenkamp et al., 2009a; Lau et al., 2007; Sugita et al., 2008). In theory, quantitative PCR methods could contribute to a clarification. However, there are no standard values for clinically relevant DNA concentrations in ocular materials and neither the diagnostic

Virus Diagnostics and Antiviral Therapy in Acute Retinal Necrosis (ARN) 23

The clinical ARN diagnosis needs the critical validation by virus-specific PCR. During the initial stage, only PCR allows rapid and valid results. Time-delayed PCR diagnostics lead to diminished test sensitivity (de Boer et al., 1996; Knox et al., 1998). Due to the high test sensitivity of the PCR, 20-50 μl sample volume is sufficient in most cases. The PCR discrimination beween HSV-1 and HSV-2 is an established method. Real-time PCR methods allow the quantitation of viral loads in copy number per ml. Although there are no standards available for a clinically relevant virus load value, the quantitation is relevant to discriminate between the major causative agent and an additional, perhaps weak reactivation of another

The quantitative determination of antibody titers from the anterior chamber or the vitreous in comparison to the serum levels is an indirect and supporting procedure for virus-specific diagnostics at delayed time points. For the determination of the Goldmann-Witmer coefficient (antibody index, AI; Goldmann & Witmer, 1954), the intraocular and serum antibody

AI = (antibody titer punctate/antibody titer serum) / (total IgG punctate/total IgG serum) Most authors consider an AI > 2-3 an obvious indicator of intraocular antibody production (de Boer et al., 1994; Dussaix et al., 1987; Fekkar et al., 2008; Pepose et al., 1992). Serological procedures have the disadvantages that significant antibody levels can be expected only after one to two weeks and that a false-negative AI can result from massive disturbance of the blood-eye barrier. In the case of latently peristing herpesviruses, an ocular reactivation does not necessarily lead to a significant AI increase. Moreover, there are serological crossreactivites between HSV and VZV (Pepose et al., 1992). Finally, the intraocular antibody generation can be variable in immunosuppressed or HIV-infected patients (de Boer et al.,

**Aciclovir** by the parenteral route is the drug of choice in severe, acute HSV or VZV infections. The acyclic guanosine derivate aciclovir is specifically activated by the viral enzyme thymidine kinase of HSV or VZV to its monophosphate. Ubiquitous cellular kinases are responsible for the conversion to aciclovir triphosphate which is a specific inhibitor for the viral DNA polymerase (de Clercq, 2004). The dosage is based on tissue culture-derived determinations of the 50%-inhibitory concentration (IC50) of aciclovir against HSV-1, HSV-2, or VZV. Due to a lack of standardisation of the assay conditions and the test viruses, these values are variable, up to several orders of magnitude. The IC50 values were 0.02 to 13.5 μg/ml for HSV-1, 0.01 to 9.9 μg/ml for HSV-2 and 0.12 to 10.8 μg/ml for VZV (O'Brien & Campoli-Richards, 1989). Due to the three hours half life of aciclovir, it should be administered intraveneously at 10 mg/kg for ten to 14 days three times daily. Consecutively, the oral application of five times daily 800 mg for further six weeks is recommended (Blumenkranz et al., 1986; Duker & Blumenkranz, 1991; Morse & Mizoguchi, 1995; Palay et al., 1991). This

herpesvirus, *e. g.,* under immunosuppression (Hasselbach et al., 2008).

titers and total IgG values are included in the following formula:

1996; Doornenbal et al., 1996; Kijlstra et al., 1989, 1990).

**4.1 Drugs directed against -herpesviruses** 

**3.2 Nucleic acid diagnostics** 

**3.3 Antibody assays** 

**4. Therapy** 

samples nor the PCR methods are sufficiently standardized. In summary, EBV seems to play no or -if at all- only a minor role in ARN development.

#### **2.3 Clinical course**

Almost 90% of all ARN cases remain unilateral (Hillenkamp et al., 2009a; Muthiah et al., 2007; Usui et al., 2008; Vandercam et al., 2008). In approximately 10% of the patients, also the contralateral eye is affected within one to six weeks, in an extreme case after up to 34 years (Falcone & Brockhurst, 1993; Saari et al., 1982; Schlingemann et al., 1996). A case-control study revealed that aciclovir therapy considerably reduces the risk for the contralateral eye (Palay et al., 1991). As soon as the ARN diagnosis is made, antiviral therapy should be started in order to avoid disease progression. Longer termed aciclovir prophylaxis should be considered (Cordero-Coma et al., 2007).

An increased ARN risk was discovered for the HLA alleles DQw7, DR4, and Bw62 (odds ratio: 5.2 and 7.3 respectively; Holland et al., 1989). Moreover, there is a 20-fold increased risk (p=0.05) for a fulminant ARN course in the presense of the HLA DR9 allele (Matsuo & Matsuo, 1991). Several case reports describe ARN following HSV encephalitis (Bristow et al., 2006; de la Blanchardiere et al., 2000; Gain et al., 2002; Ganatra et al., 2000; Gaynor et al., 2001; Hadden & Berry, 2002; Kim & Yoon, 2002; Maertzdorf et al., 2001; Pavésio et al., 1997; Yamamoto et al., 2007). In a retrospective study, thirteen of 52 patients showed infectious or non-infectious neurological diseases in the medical history (Vandercam et al., 2008). Four of eleven patients had HSV encephalitis 20.6 months (mean) prior to ARN. Two of 28 patients had VZV encephalitis 28 months (mean) before. The HSV patients showed a unilateral ARN, whereas both immunosuppressed VZV patients developed bilateral ARN. Besides various case reports, these results clearly demonstrate herpes encephalitis as a risk factor for ARN which needs attention in neurology and ophthalmology.

#### **3. Virus diagnostics**

#### **3.1 Preanalytical conditions**

Diagnostic samples can be generated in early stages by puncture of the anterior chamber, by paracentesis, by fine needle aspiration of vitreous fluid, or in advanced conditions by therapeutic pars plana vitrectomy (Winterhalter et al., 2007). The rapid PCR demonstration of virus DNA is highly important for the therapy, because specific antiviral drugs are used. Since herpesviruses and their DNA genomes are rather stable, the transport of fluid from the anterior chamber or from the vitreous does not need special precautions. Only in the case of prolonged transport times, the samples should be shipped in cooled conditions. The major diagnostic test is the PCR for herpesviral DNA for the direct demonstration of the causative agent. Virus-specific serologic tests can serve as indirect methods in order to show local antibody production at delayed time points. The major advantage of PCR testing is the low sample volume required and the independence of time-delayed immune reaction. Due to the rareness of ARN and to the critical contribution of antiviral therapy, the authors recommend the genotypic sensitivity test after demonstration of herpesvirus DNA. In case of failure of the antiviral therapy, this allows the rapid decision for either switching to cidofovir or foscarnet or for increasing aciclovir dosage in case of preserved drug sensitivity.

#### **3.2 Nucleic acid diagnostics**

22 Antiviral Drugs – Aspects of Clinical Use and Recent Advances

samples nor the PCR methods are sufficiently standardized. In summary, EBV seems to play

Almost 90% of all ARN cases remain unilateral (Hillenkamp et al., 2009a; Muthiah et al., 2007; Usui et al., 2008; Vandercam et al., 2008). In approximately 10% of the patients, also the contralateral eye is affected within one to six weeks, in an extreme case after up to 34 years (Falcone & Brockhurst, 1993; Saari et al., 1982; Schlingemann et al., 1996). A case-control study revealed that aciclovir therapy considerably reduces the risk for the contralateral eye (Palay et al., 1991). As soon as the ARN diagnosis is made, antiviral therapy should be started in order to avoid disease progression. Longer termed aciclovir prophylaxis should be

An increased ARN risk was discovered for the HLA alleles DQw7, DR4, and Bw62 (odds ratio: 5.2 and 7.3 respectively; Holland et al., 1989). Moreover, there is a 20-fold increased risk (p=0.05) for a fulminant ARN course in the presense of the HLA DR9 allele (Matsuo & Matsuo, 1991). Several case reports describe ARN following HSV encephalitis (Bristow et al., 2006; de la Blanchardiere et al., 2000; Gain et al., 2002; Ganatra et al., 2000; Gaynor et al., 2001; Hadden & Berry, 2002; Kim & Yoon, 2002; Maertzdorf et al., 2001; Pavésio et al., 1997; Yamamoto et al., 2007). In a retrospective study, thirteen of 52 patients showed infectious or non-infectious neurological diseases in the medical history (Vandercam et al., 2008). Four of eleven patients had HSV encephalitis 20.6 months (mean) prior to ARN. Two of 28 patients had VZV encephalitis 28 months (mean) before. The HSV patients showed a unilateral ARN, whereas both immunosuppressed VZV patients developed bilateral ARN. Besides various case reports, these results clearly demonstrate herpes encephalitis as a risk factor for ARN

Diagnostic samples can be generated in early stages by puncture of the anterior chamber, by paracentesis, by fine needle aspiration of vitreous fluid, or in advanced conditions by therapeutic pars plana vitrectomy (Winterhalter et al., 2007). The rapid PCR demonstration of virus DNA is highly important for the therapy, because specific antiviral drugs are used. Since herpesviruses and their DNA genomes are rather stable, the transport of fluid from the anterior chamber or from the vitreous does not need special precautions. Only in the case of prolonged transport times, the samples should be shipped in cooled conditions. The major diagnostic test is the PCR for herpesviral DNA for the direct demonstration of the causative agent. Virus-specific serologic tests can serve as indirect methods in order to show local antibody production at delayed time points. The major advantage of PCR testing is the low sample volume required and the independence of time-delayed immune reaction. Due to the rareness of ARN and to the critical contribution of antiviral therapy, the authors recommend the genotypic sensitivity test after demonstration of herpesvirus DNA. In case of failure of the antiviral therapy, this allows the rapid decision for either switching to cidofovir or foscarnet or for increasing aciclovir dosage in case of preserved drug sensitivity.

no or -if at all- only a minor role in ARN development.

which needs attention in neurology and ophthalmology.

considered (Cordero-Coma et al., 2007).

**2.3 Clinical course** 

**3. Virus diagnostics** 

**3.1 Preanalytical conditions** 

The clinical ARN diagnosis needs the critical validation by virus-specific PCR. During the initial stage, only PCR allows rapid and valid results. Time-delayed PCR diagnostics lead to diminished test sensitivity (de Boer et al., 1996; Knox et al., 1998). Due to the high test sensitivity of the PCR, 20-50 μl sample volume is sufficient in most cases. The PCR discrimination beween HSV-1 and HSV-2 is an established method. Real-time PCR methods allow the quantitation of viral loads in copy number per ml. Although there are no standards available for a clinically relevant virus load value, the quantitation is relevant to discriminate between the major causative agent and an additional, perhaps weak reactivation of another herpesvirus, *e. g.,* under immunosuppression (Hasselbach et al., 2008).

#### **3.3 Antibody assays**

The quantitative determination of antibody titers from the anterior chamber or the vitreous in comparison to the serum levels is an indirect and supporting procedure for virus-specific diagnostics at delayed time points. For the determination of the Goldmann-Witmer coefficient (antibody index, AI; Goldmann & Witmer, 1954), the intraocular and serum antibody titers and total IgG values are included in the following formula:

AI = (antibody titer punctate/antibody titer serum) / (total IgG punctate/total IgG serum)

Most authors consider an AI > 2-3 an obvious indicator of intraocular antibody production (de Boer et al., 1994; Dussaix et al., 1987; Fekkar et al., 2008; Pepose et al., 1992). Serological procedures have the disadvantages that significant antibody levels can be expected only after one to two weeks and that a false-negative AI can result from massive disturbance of the blood-eye barrier. In the case of latently peristing herpesviruses, an ocular reactivation does not necessarily lead to a significant AI increase. Moreover, there are serological crossreactivites between HSV and VZV (Pepose et al., 1992). Finally, the intraocular antibody generation can be variable in immunosuppressed or HIV-infected patients (de Boer et al., 1996; Doornenbal et al., 1996; Kijlstra et al., 1989, 1990).

#### **4. Therapy**

#### **4.1 Drugs directed against -herpesviruses**

**Aciclovir** by the parenteral route is the drug of choice in severe, acute HSV or VZV infections. The acyclic guanosine derivate aciclovir is specifically activated by the viral enzyme thymidine kinase of HSV or VZV to its monophosphate. Ubiquitous cellular kinases are responsible for the conversion to aciclovir triphosphate which is a specific inhibitor for the viral DNA polymerase (de Clercq, 2004). The dosage is based on tissue culture-derived determinations of the 50%-inhibitory concentration (IC50) of aciclovir against HSV-1, HSV-2, or VZV. Due to a lack of standardisation of the assay conditions and the test viruses, these values are variable, up to several orders of magnitude. The IC50 values were 0.02 to 13.5 μg/ml for HSV-1, 0.01 to 9.9 μg/ml for HSV-2 and 0.12 to 10.8 μg/ml for VZV (O'Brien & Campoli-Richards, 1989). Due to the three hours half life of aciclovir, it should be administered intraveneously at 10 mg/kg for ten to 14 days three times daily. Consecutively, the oral application of five times daily 800 mg for further six weeks is recommended (Blumenkranz et al., 1986; Duker & Blumenkranz, 1991; Morse & Mizoguchi, 1995; Palay et al., 1991). This

Virus Diagnostics and Antiviral Therapy in Acute Retinal Necrosis (ARN) 25

and sequencing of the viral gene for thymidine kinase and by the sequence comparison with known resistant viruses within a few days. The cultural resistance testing depends on the successful virus isolation. This procedure is slower, hardly standardized and only possible in a few reference laboratories. More than 90% of the resistance cases result from mutations of the thymidine kinase gene. In case of resistance, cidofovir and foscarnet are usually the only available alternatives, since their activity mechanism is independent of the viral thymi-

**Cidofovir** is an acyclic nucleosid phosphonate with a broad activity spectrum against DNA viruses (de Clercq & Holý, 2005). Host cell kinases convert cidofovir to the active diphosphonyl ester which acts as a competitive inhibitor of the viral DNA polymerases and induces viral DNA chain termination. Aciclovir-resistant virus strain may be susceptible to cidofovir. The drug is administered intraveneously since its oral bioavailability is only 5%. The peculiarity of cidofovir is its very high intracellular half-life time of more than 24 hours (de Clercq & Holý, 2005). Cidofovir should be used only as a drug of second choice. It is infused in a dose of 5 mg/kg over one hour once weekly in two weeks. For maintenance, the infusion is then repeated every second week in the same dosage. The major disadvantage of cidofovir is its nephrotoxicity which is due to the accumulation of this drug by an anion transporter system of the proximal tubuli of the renal cortex (Ho et al., 2000). Since cidofovir

**Foscarnet.** In the case of a proven resistance against aciclovir, ganciclovir, or their prodrugs, foscarnet is the drug of choice. Foscarnet is a pyrophosphate analogon which occupies the pyrophosphate binding site on the herpesviral DNA polymerase and inhibits the release of pyrophosphate from the terminal nucleotide triphosphate of the growing viral DNA chain (Biron, 2006). Due to the very low oral bioavailability of 20%, the drug is administered by large-volume intraveneous infusions. Foscarnet is used in a dosage of 60 mg/kg every eight hours. Foscarnet is renally eliminated without any metabolic modification. In patients with diminished renal function, the dosis must be adjusted to the creatinine clearance value. The

**Intravitreal application.** Vitreous concentrations of aciclovir following intravenous administration has not yet been tested on a broad basis. Therefore, in patients, who do not respond to intravenous therapy, the intravitreal application of the respective antiviral drug should be considered in order to rapidly achieve high concentrations of the drug and, thus, an improved prognosis (Hillenkamp et al., 2009a, 2010; Scott et al., 2002; Velez et al., 2001; Zambarakji et al., 2002). This strategy allows high intraocular drug levels under reduced

In contrast to the -herpesviruses, CMV lacks a viral thymidine kinase. Presently, four drugs are licensed for CMV therapy: ganciclovir, valganciclovir, cidofovir, and foscarnet. All

**Ganciclovir** and its orally available valyl ester-derivate valganciclovir are the drugs of first choice for the therapy of CMV-induced diseases (de Clercq, 2004). The substances are monophosphorylated in CMV-infected cells by the CMV-specific protein kinase UL97, and subsequently triphosphorylated by cellular kinases. The incorporation of the acyclic

dine kinase. Both drugs can also be used for ganciclovir-resistant CMV strains.

is renally secreted, it must be combined with probenecid for kidney protection.

systemic exposure. Studies on repeated injections are not yet available.

of them target the viral DNA polymerase and inhibit the viral DNA synthesis.

major side effect of foscarnet is its nephrotoxicity.

**4.2 Drugs directed against cytomegalovirus** 

recommendation is based on a case-control study in which most of the bilateral ARN cases ocurred within a period of six weeks and in which 90% of the bilateral ARN cases could have been avoided by aciclovir therapy (Palay et al., 1991). After the start of the antiviral therapy, new lesions should not occur from the second day on. From the fourth or fifth day on, the retinal infiltrates should show a tendence for regression. After one month, a complete remission should be achieved (Blumenkranz et al., 1986). If this is not accomplished, either there was an insufficient drug dosage, or antiviral resistance has developed which is more frequently seen in immunosuppressed patients. The side effects of aciclovir are rather weak and rare and may include mild serum creatinine increase, nausea, and vomiting. Presently, the authors recommend aciclovir as first-line therapy of choice in the early phase of the disease. This is based on the long-termed experience with this drug. Moreover, this excludes influences from the intra- and interindividual variability of the oral bioavailability of valaciclovir (Hillenkamp et al., 2009a, b, 2010; Phan et al., 2003). The management of ARN by antiviral drugs has been summarized in a recent review article (Tam eta al., 2010).

**Valaciclovir** is the valyl ester of aciclovir, which is quickly taken up into enterocytes after oral administration via enteric aminoacid transport systems and which is then hydrolyzed to the active prodrug aciclovir (Granero & Amidon, 2006; Katragadda et al., 2005). The oral bioavailability of valaciclovir of 54% is three times higher than that of aciclovir (Soul-Lawton et al., 1995). When 1000 mg valaciclovir were administered three times daily, aciclovir serum levels of 4.41 μg/ml and aciclovir levels in the vitreous of 1.03 μg/ml were reached. These concentrations are in the IC50 range for most HSV or VZV isolates. The lower peak concentrations during oral in comparison to parenteral aciclovir therapy minimize the risk for renal side effects (Huynh et al., 2008).

**Famciclovir** is an orally available di-acetyl derivate of penciclovir. By deacetylation, famciclovir is metabolized in the liver to the active prodrug penciclovir which is secreted without modification by the kidneys (Chakrabarty et al., 2004). The oral bioavailability of famciclovir is 77% and, thus, approximately 1.5-fold higher than that of valaciclovir (Soul-Lawton et al., 1995) or 3.4-fold higher than that of aciclovir (15–30%; Fletcher & Bean, 1985). By oral administration of 500 mg every eight hours, intravitreal penciclovir concentrations of 1.2 μg/ml can be reached (Chong et al., 2009), which is appropriate for the therapy of nonresistant HSV-1, HSV-2, or VZV strains. In some single case reports, famciclovir was active against aciclovir-resistant VZV strains (Figueroa et al., 1997). However, the main reasons for aciclovir resistance are mutations of the viral thymidine kinase gene, which would typically also result in penciclovir resistance.

Based on case reports with orally available prodrugs of aciclovir (Emerson et al., 2006; Savant et al., 2004), a pilot study was performed with ten eyes of eight patients (Aizman et al., 2007). Under the oral therapy with 1 g valganciclovir or 500 mg famaciclovir three times daily, the ARN regression occurred within six days and the maximal improvement within 17 days without any case of contralateral ARN during further 36 weeks of observation. As long as randomized prospective studies on the efficiency of the oral aciclovir alternatives are not yet available, the initial standard therapy should be performed with intraveneous aciclovir, only.

**Resistance mutations.** Especially in immunosuppressed patients, resistance development against aciclovir is observed frequently. However, underdosage must be excluded first. Under optimal conditions, the genotypic viral resistance can be determined by DNA PCR

recommendation is based on a case-control study in which most of the bilateral ARN cases ocurred within a period of six weeks and in which 90% of the bilateral ARN cases could have been avoided by aciclovir therapy (Palay et al., 1991). After the start of the antiviral therapy, new lesions should not occur from the second day on. From the fourth or fifth day on, the retinal infiltrates should show a tendence for regression. After one month, a complete remission should be achieved (Blumenkranz et al., 1986). If this is not accomplished, either there was an insufficient drug dosage, or antiviral resistance has developed which is more frequently seen in immunosuppressed patients. The side effects of aciclovir are rather weak and rare and may include mild serum creatinine increase, nausea, and vomiting. Presently, the authors recommend aciclovir as first-line therapy of choice in the early phase of the disease. This is based on the long-termed experience with this drug. Moreover, this excludes influences from the intra- and interindividual variability of the oral bioavailability of valaciclovir (Hillenkamp et al., 2009a, b, 2010; Phan et al., 2003). The management of ARN

by antiviral drugs has been summarized in a recent review article (Tam eta al., 2010).

for renal side effects (Huynh et al., 2008).

also result in penciclovir resistance.

aciclovir, only.

**Valaciclovir** is the valyl ester of aciclovir, which is quickly taken up into enterocytes after oral administration via enteric aminoacid transport systems and which is then hydrolyzed to the active prodrug aciclovir (Granero & Amidon, 2006; Katragadda et al., 2005). The oral bioavailability of valaciclovir of 54% is three times higher than that of aciclovir (Soul-Lawton et al., 1995). When 1000 mg valaciclovir were administered three times daily, aciclovir serum levels of 4.41 μg/ml and aciclovir levels in the vitreous of 1.03 μg/ml were reached. These concentrations are in the IC50 range for most HSV or VZV isolates. The lower peak concentrations during oral in comparison to parenteral aciclovir therapy minimize the risk

**Famciclovir** is an orally available di-acetyl derivate of penciclovir. By deacetylation, famciclovir is metabolized in the liver to the active prodrug penciclovir which is secreted without modification by the kidneys (Chakrabarty et al., 2004). The oral bioavailability of famciclovir is 77% and, thus, approximately 1.5-fold higher than that of valaciclovir (Soul-Lawton et al., 1995) or 3.4-fold higher than that of aciclovir (15–30%; Fletcher & Bean, 1985). By oral administration of 500 mg every eight hours, intravitreal penciclovir concentrations of 1.2 μg/ml can be reached (Chong et al., 2009), which is appropriate for the therapy of nonresistant HSV-1, HSV-2, or VZV strains. In some single case reports, famciclovir was active against aciclovir-resistant VZV strains (Figueroa et al., 1997). However, the main reasons for aciclovir resistance are mutations of the viral thymidine kinase gene, which would typically

Based on case reports with orally available prodrugs of aciclovir (Emerson et al., 2006; Savant et al., 2004), a pilot study was performed with ten eyes of eight patients (Aizman et al., 2007). Under the oral therapy with 1 g valganciclovir or 500 mg famaciclovir three times daily, the ARN regression occurred within six days and the maximal improvement within 17 days without any case of contralateral ARN during further 36 weeks of observation. As long as randomized prospective studies on the efficiency of the oral aciclovir alternatives are not yet available, the initial standard therapy should be performed with intraveneous

**Resistance mutations.** Especially in immunosuppressed patients, resistance development against aciclovir is observed frequently. However, underdosage must be excluded first. Under optimal conditions, the genotypic viral resistance can be determined by DNA PCR and sequencing of the viral gene for thymidine kinase and by the sequence comparison with known resistant viruses within a few days. The cultural resistance testing depends on the successful virus isolation. This procedure is slower, hardly standardized and only possible in a few reference laboratories. More than 90% of the resistance cases result from mutations of the thymidine kinase gene. In case of resistance, cidofovir and foscarnet are usually the only available alternatives, since their activity mechanism is independent of the viral thymidine kinase. Both drugs can also be used for ganciclovir-resistant CMV strains.

**Cidofovir** is an acyclic nucleosid phosphonate with a broad activity spectrum against DNA viruses (de Clercq & Holý, 2005). Host cell kinases convert cidofovir to the active diphosphonyl ester which acts as a competitive inhibitor of the viral DNA polymerases and induces viral DNA chain termination. Aciclovir-resistant virus strain may be susceptible to cidofovir. The drug is administered intraveneously since its oral bioavailability is only 5%. The peculiarity of cidofovir is its very high intracellular half-life time of more than 24 hours (de Clercq & Holý, 2005). Cidofovir should be used only as a drug of second choice. It is infused in a dose of 5 mg/kg over one hour once weekly in two weeks. For maintenance, the infusion is then repeated every second week in the same dosage. The major disadvantage of cidofovir is its nephrotoxicity which is due to the accumulation of this drug by an anion transporter system of the proximal tubuli of the renal cortex (Ho et al., 2000). Since cidofovir is renally secreted, it must be combined with probenecid for kidney protection.

**Foscarnet.** In the case of a proven resistance against aciclovir, ganciclovir, or their prodrugs, foscarnet is the drug of choice. Foscarnet is a pyrophosphate analogon which occupies the pyrophosphate binding site on the herpesviral DNA polymerase and inhibits the release of pyrophosphate from the terminal nucleotide triphosphate of the growing viral DNA chain (Biron, 2006). Due to the very low oral bioavailability of 20%, the drug is administered by large-volume intraveneous infusions. Foscarnet is used in a dosage of 60 mg/kg every eight hours. Foscarnet is renally eliminated without any metabolic modification. In patients with diminished renal function, the dosis must be adjusted to the creatinine clearance value. The major side effect of foscarnet is its nephrotoxicity.

**Intravitreal application.** Vitreous concentrations of aciclovir following intravenous administration has not yet been tested on a broad basis. Therefore, in patients, who do not respond to intravenous therapy, the intravitreal application of the respective antiviral drug should be considered in order to rapidly achieve high concentrations of the drug and, thus, an improved prognosis (Hillenkamp et al., 2009a, 2010; Scott et al., 2002; Velez et al., 2001; Zambarakji et al., 2002). This strategy allows high intraocular drug levels under reduced systemic exposure. Studies on repeated injections are not yet available.

#### **4.2 Drugs directed against cytomegalovirus**

In contrast to the -herpesviruses, CMV lacks a viral thymidine kinase. Presently, four drugs are licensed for CMV therapy: ganciclovir, valganciclovir, cidofovir, and foscarnet. All of them target the viral DNA polymerase and inhibit the viral DNA synthesis.

**Ganciclovir** and its orally available valyl ester-derivate valganciclovir are the drugs of first choice for the therapy of CMV-induced diseases (de Clercq, 2004). The substances are monophosphorylated in CMV-infected cells by the CMV-specific protein kinase UL97, and subsequently triphosphorylated by cellular kinases. The incorporation of the acyclic

Virus Diagnostics and Antiviral Therapy in Acute Retinal Necrosis (ARN) 27

the start of ARN therapy is critical for the outcome the initiation of the therapy for most alternative causes is by far less urgent. Due to the similar clinical appearance, toxoplasmosis chorioretinitis is an important differential diagnosis (Balansard et al., 2005; Hasselbach et al., 2008; Moshfeghi et al., 2004). An ocular manifestation of syphilis can show many different symptoms and can mimick various diseases. In contrast to ARN, CMV retinitis shows weak inflammation signs in the anterior chamber and the vitreous. Patients with CMV retinitis are usually infected with human immunodeficiency virus (HIV) with less than 50 CD4+ T cells/μl. CMV retinitis is resistant to aciclovir therapy. Therefore, the early PCR test for

Finally, progressive outer retina necrosis (PORN) forms another differential diagnosis, which was mainly described in HIV patients (Forster et al., 1990). Typically, the outer retinal layers are primarily affected multifocally, while the inner retinal layers are less concerned. In contrast to ARN, there is no vasculitis component. The course of PORN disease is extremely rapid, spreading to the the deep retinal layers and leading to retinal detachment. Pa-

ARN occurs in up to one per million persons per year. The virus-caused disease remains unilateral in approximately 90% of the cases. Without treatment, ARN shows poor prognosis. The immediate calculated antiviral therapy by aciclovir or its prodrugs is justified, since approximately 70% of the cases are caused by VZV and 30% by HSV. The causative role of EBV remains controversial; often, EBV reactivation occurs concomitantly with VZV reactivation. While EBV reactivation cannot be treated efficiently, aciclovir is appropriate for VZV and HSV reactivations. The very rare case of CMV in ARN is an indication for ganciclovir or its prodrug. The virus-specific DNA PCR test from fluid of the anterior chamber or the vitreous provides the critical indication for the specific therapy. Disease progression and complications rates can be limited by additional immediate conservative and surgical therapy.

The scientific work underlying this manuscript was supported in part by the Deutsche Forschungsgemeinschaft (Bonn), the Excellence Cluster Inflammation at Interfaces (Kiel), and

Abe, T.; Tsuchida, K.; Tamai, M. (1996). A comparative study of the polymerase chain reac-

Aizman, A.; Johnson, M. W.; Elner, S. G. (2007). Treatment of acute retinal necrosis syndrome with oral antiviral medications. *Ophthalmology,* Vol. 114, No. 2, pp. 307-312 Balansard, B.; Bodaghi, B.; Cassoux, N.; Fardeau, C.; Romand, S.; Rozenberg, F.; Rao, N. A.;

syndrome. *British Journal of Ophthalmology,* Vol. 89, No. 1, pp. 96-101

tion and local antibody production in acute retinal necrosis syndrome and cytomegalovirus retinitis. *Graefes Archive for Clinical and Experimental Ophthalmology,*

Lehoang, P. (2005). Necrotising retinopathies simulating acute retinal necrosis

tients with PORN usually show coinfection with HIV and VZV.

the Varicella-Zoster Virus Research Foundation (New York).

Vol. 234, No. 7, pp. 419-424

virus DNA is necessary.

**5. Conclusion** 

**6. Acknowledgements** 

**7. References** 

ganciclovir triphosphate into the growing viral DNA chain results in the blockade of polymerase translocation (Reid et al., 1988). Since the oral bioavailability of ganiclovir is only approximately 5%, the drug should be administered intravenously during the ganciclovir disease. In most cases, 10 mg/kg i.v. daily should be sufficient for the CMV therapy in ARN cases. The oral bioavailability of valganciclovir is approximately 60%. A daily dose of 900 mg will yield serum concentrations comparable to 5 mg/kg intraveneous ganciclovir or a 1,7-fold serum concentration in comparison to 1000 mg oral ganciclovir (Cvetković & Wellington, 2005). The major side effect of systemic ganciclovir therapy is neutropenia in approximately 8% of the patients. Therefore, ganciclovir therapy needs the regular control of blood counts, as well as the surveillance of renal function (Paya et al., 2004).

**UL97 resistance mutations.** Mutations of the UL97 protein kinase of CMV are the major cause of resistance against ganciclovir and its derivates. The resistence is determined genotypically by sequencing if the viral genes for the UL97 kinase and for the DNA polymerase. The most frequent ganciclovir resistence mutations in UL97 (codons 460, 520, 590-607) inhibit ganciclovir phosphorylation which is the prerequsite for antiviral activity (Chou et al., 2008). The activity of cidofovir and foscarnet is independent of the protein kinase UL97 and appropriate for the therapy of many DNA viruses.

#### **4.3 Differential diagnosis**

During the early disease stages, additional infectious agents, rheumatological disorders, autoimmune uveitis, or intraocular lymphomas have to be considered (Table 1). Whereas


Table 1. Differential diagnosis of acute retinal necrosis.

the start of ARN therapy is critical for the outcome the initiation of the therapy for most alternative causes is by far less urgent. Due to the similar clinical appearance, toxoplasmosis chorioretinitis is an important differential diagnosis (Balansard et al., 2005; Hasselbach et al., 2008; Moshfeghi et al., 2004). An ocular manifestation of syphilis can show many different symptoms and can mimick various diseases. In contrast to ARN, CMV retinitis shows weak inflammation signs in the anterior chamber and the vitreous. Patients with CMV retinitis are usually infected with human immunodeficiency virus (HIV) with less than 50 CD4+ T cells/μl. CMV retinitis is resistant to aciclovir therapy. Therefore, the early PCR test for virus DNA is necessary.

Finally, progressive outer retina necrosis (PORN) forms another differential diagnosis, which was mainly described in HIV patients (Forster et al., 1990). Typically, the outer retinal layers are primarily affected multifocally, while the inner retinal layers are less concerned. In contrast to ARN, there is no vasculitis component. The course of PORN disease is extremely rapid, spreading to the the deep retinal layers and leading to retinal detachment. Patients with PORN usually show coinfection with HIV and VZV.

#### **5. Conclusion**

26 Antiviral Drugs – Aspects of Clinical Use and Recent Advances

ganciclovir triphosphate into the growing viral DNA chain results in the blockade of polymerase translocation (Reid et al., 1988). Since the oral bioavailability of ganiclovir is only approximately 5%, the drug should be administered intravenously during the ganciclovir disease. In most cases, 10 mg/kg i.v. daily should be sufficient for the CMV therapy in ARN cases. The oral bioavailability of valganciclovir is approximately 60%. A daily dose of 900 mg will yield serum concentrations comparable to 5 mg/kg intraveneous ganciclovir or a 1,7-fold serum concentration in comparison to 1000 mg oral ganciclovir (Cvetković & Wellington, 2005). The major side effect of systemic ganciclovir therapy is neutropenia in approximately 8% of the patients. Therefore, ganciclovir therapy needs the regular control of blood counts, as well as the surveillance of renal function (Paya et al.,

**UL97 resistance mutations.** Mutations of the UL97 protein kinase of CMV are the major cause of resistance against ganciclovir and its derivates. The resistence is determined genotypically by sequencing if the viral genes for the UL97 kinase and for the DNA polymerase. The most frequent ganciclovir resistence mutations in UL97 (codons 460, 520, 590-607) inhibit ganciclovir phosphorylation which is the prerequsite for antiviral activity (Chou et al., 2008). The activity of cidofovir and foscarnet is independent of the protein kinase UL97 and

During the early disease stages, additional infectious agents, rheumatological disorders, autoimmune uveitis, or intraocular lymphomas have to be considered (Table 1). Whereas

**Disease Diagnosis First-line therapy** 

Progressive outer retina necrosis PCR, serology dependent on the agent

Behçet's disease clinic, pathergia test immunosuppression Sarcoidosis histology immunosuppression Idiopathic chorioretinitis exclusion diagnosis immunosuppression Idiopathic retinovasculitis exclusion diagnosis immunosuppression Intraocular lymphoma cytology, tumor genetics radiochemotherapy

Table 1. Differential diagnosis of acute retinal necrosis.

Toxoplasmosis retinitis serology, PCR pyrimethamine/sulfonamide Tuberculosis culture, PCR antimycobacterial therapy Endogeneous endophthalmitis culture, PCR dependent on the agent Bacterial eye infection culture, PCR dependent on the agent Fungal eye infection culture, PCR, Antigen Candida: Fluconazol

Aspergillus: Voriconazol

ARN by varicella zoster virus PCR aciclovir ARN by herpes simplex virus PCR aciclovir ARN by cytomegalovirus PCR ganciclovir ARN by Epstein-Barr virus PCR not available

Cytomegalovirus retinitis PCR ganciclovir Lyme borreliosis serology, PCR cephalosporin Syphilis serology penicillin

appropriate for the therapy of many DNA viruses.

**4.3 Differential diagnosis** 

2004).

ARN occurs in up to one per million persons per year. The virus-caused disease remains unilateral in approximately 90% of the cases. Without treatment, ARN shows poor prognosis. The immediate calculated antiviral therapy by aciclovir or its prodrugs is justified, since approximately 70% of the cases are caused by VZV and 30% by HSV. The causative role of EBV remains controversial; often, EBV reactivation occurs concomitantly with VZV reactivation. While EBV reactivation cannot be treated efficiently, aciclovir is appropriate for VZV and HSV reactivations. The very rare case of CMV in ARN is an indication for ganciclovir or its prodrug. The virus-specific DNA PCR test from fluid of the anterior chamber or the vitreous provides the critical indication for the specific therapy. Disease progression and complications rates can be limited by additional immediate conservative and surgical therapy.

#### **6. Acknowledgements**

The scientific work underlying this manuscript was supported in part by the Deutsche Forschungsgemeinschaft (Bonn), the Excellence Cluster Inflammation at Interfaces (Kiel), and the Varicella-Zoster Virus Research Foundation (New York).

#### **7. References**


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**3** 

Christophe Bazin

*France* 

**Leflunomide an Immunosuppressive Drug** 

*Hôpital Européen Georges-Pompidou, Assistance Publique – Hôpitaux de Paris* 

BK virus is a polyomavirus belonging to the *papovaviridae* branch. In addition to BK, the human polyomavirus family includes John Cunningham virus (JCV), Washington University virus (WUV), Karolinska Institute virus (KIV) and Merkel cell viruses (Boothpur et al. 2010). BK virus is a virus without a shell and it has a double-stranded circular nonenveloped DNA. It was first discovered and isolated in 1971 just like JC virus, responsible for Progressive Multifocal Leukoencephalopathy (PML). Contamination usually occurs during early childhood through the airway without clinical symptoms. BK virus seroprevalence in general population is around 60%. The main latency areas are the kidney and the urothelium. Asymptomatic BK virus infection is often acquired in childhood and the virus persists in a dormant state in urothelium and kidneys of healthy and immunocompetent individuals, where it can be reactivated under immunosuppression

Urinary viral prevalence for BK virus is between 0.3% and 6% in general population, and increases in functions of immunosuppression degree; between 10% and 45% in patients after renal transplant, 30% in patients after bone marrow graft and 25% in patients with Human immunodeficiency virus. In patients with renal graft, the annual incidence of the

BK virus-associated nephropathy seems to be promoted by the concurrent presence of several risk factors. The immunosuppressive regimen strength, with high level blood concentrations, is the first factor involved. Most patients affected by BK virus-associated nephropathy previously had an intensification of immunosuppressive regimen due to a rejection event or a treatment including tacrolimus and/or mycophenolate mofetil

nephropathy is between 3% and 5% (Randhawa et al. 2000; Pavlakis et al. 2006).

**1. Introduction** 

(Nickeleit et al. 2000a; Brocker et al. 2011).

**1.2 Prevalence and incidence** 

**1.3 Risk factors** 

**1.1 BK Virus** 

 **for Antiviral Purpose in Treatment for** 

**BK Virus-Associated Nephropathy** 

 **After Kidney Transplantation** 

me in ocular fluids of patients with uveitis. *British Journal of Ophthalmology,* Vol. 92, No. 7, pp. 928-932

