Epstein-Barr Virus in Multiple Sclerosis

*Gulfaraz Khan and Asma Hassani*

## **Abstract**

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system in which the body's immune system is abnormally directed towards the myelin sheaths covering the nerve fibers. What triggers the neuroinflammation and autoimmune destruction of the myelin sheaths remains unknown. However, it is widely accepted that susceptibility depends on a combination of genetic and environmental factors and their interactions. With little chance of influencing genetic predisposition, the importance of identifying risk factors which could be modulated to either prevent the on-set of MS or to ameliorate the course of the disease, is an attractive alternative. An accumulating body of evidence, including our own recent study involving over 1000 MS and non-MS samples, indicates that Epstein-Barr virus (EBV), a common herpesvirus, could be involved. In this chapter, we review the studies linking EBV to MS and propose an explanation by which this common virus could be involved in the pathogenesis of MS.

**Keywords:** multiple sclerosis, autoimmunity, neuroinflammation, Epstein-Barr virus, seroepidemiological evidence, postmortem studies

## **1. Introduction**

Multiple sclerosis (MS) is a progressive disease in which multiple regions in the brain, spinal cord and optic nerve undergo myelin destruction or demyelination. It is believed that an aberrant immune response mistakenly attacks the myelin sheaths in the central nervous system (CNS) resulting in the formation of focal demyelinated plaques; the hallmark of MS [1]. In spite of extensive search, the identity of the factor(s) that triggers the immune assault against the myelin remains elusive. It is generally accepted that MS is a complex disease and most likely involves both genetic and environmental factors [2]. Although no single gene has been identified to be responsible in the development of MS, certain HLA haplotypes, such as HLA-DRB1 have been shown be associated with MS susceptibility [3]. Furthermore, the fact that MS is more prevalent in certain races such as Caucasians [4, 5] and incidence rates are increasing in some ethnic groups such as blacks [6, 7] supports the involvement of genes in the development of MS. Although the risk of MS is significantly higher in individuals with first-degree relatives with MS, this still does not explain the occurrence of MS in majority of cases. In fact, MS concordance in monozygotic twins is only around 25% [8, 9]. This clearly indicates that environmental factors play a key role in the development of MS in genetically predisposed individuals.

## **1.1 Environmental risk factors for MS**

In support of the above observations, MS prevalence has been reported to be higher in the northern hemisphere, but lower towards the equator. However, recent studies indicate that this pattern of distribution, known as the latitudinal gradient, is changing in some countries such as Norway and USA [10–12]. Moreover, migration studies indicate that the increasing burden of MS is due to exposure to certain factors in the environment, which may account for a bigger proportion of MS risk than genetic factors. These studies show that leaving countries with high MS incidence prior to reaching adolescence, to regions with low MS incidence, confers protection against developing the disease [13]. Similarly, migrating in the opposite direction is linked to increased risk of developing MS [14–16]. These protective and MS predisposing effects have been shown to occur in a single generation, and this is highly unlikely to be due to effects of genes which usually manifest on longer periods of time [17].

Additionally, exposure to specific environmental agents at a young age seems to be critical in shaping the risk of developing MS [18]. The past few decades have seen a rapid accumulation of epidemiological data pointing to a number of different environmental factors that could potentially be involved in MS pathogenesis. However, no single causative agent has yet been unequivocally shown to be central to MS development [19]. Environmental risk factors associated with MS include sunlight exposure and serum levels of vitamin D, smoking, obesity, female sex hormones, and infection with Epstein-Barr virus (EBV) [20–22]. Among these factors, infection with EBV, particularly when manifested as infectious mononucleosis (IM), appears to have the most significant and consistent association with the risk of developing MS [23].

### **1.2 Infectious risk factors for MS: Hygiene hypothesis**

The notion that an infectious agent is involved in the pathogenesis of MS is not new. A number of observations, including MS outbreak in the Faroes islands during World War II, which coincided with the British occupation of the islands [24], and MS occurrence in clustering fashion (e.g. familial clustering of MS), suggested an infectious cause for MS [17]. The hygiene hypothesis was used to provide an explanation for such involvement [21], assuming that certain infections occurring during the first few years of life can protect against MS, whereas exposure to the same infections later in life, predisposes to MS [25]. The hygiene hypothesis also partly explained the geographical distribution of MS, in that it is less common in tropical regions that are known to be endemic to certain microbial infections. In these areas, children tend to acquire infections very early in life [26, 27]. Similarly, MS incidence seems to rise in tropical regions [28] that have witnessed improved feasibility of vaccines and antibiotics and enhanced sanitary conditions which have led to decreased childhood infections [29–31]. However, some epidemiological observations such as the finding that the risk of MS in individuals who have never been exposed to EBV is 10 fold lower than in those who were exposed to childhood EBV infection [32], cannot be explained by the hygiene hypothesis.

### **2. Epstein-Barr virus (EBV)**

EBV is a common human herpesvirus, infecting over 90% of the population worldwide [33]. Generally, EBV infection is considered to be one of the early asymptomatic childhood infections and in the vast majority of the infected individuals, the virus persists for life without causing disease. Bizarrely, if primary infection is delayed until adolescence, as commonly noted in developed countries, the virus can

**103**

*Epstein-Barr Virus in Multiple Sclerosis DOI: http://dx.doi.org/10.5772/intechopen.85222*

cause an acute self-limiting symptomatic infection known as infectious mononucleosis (IM) [34]. Importantly, EBV has oncogenic properties and in a very small percentage of individuals, the virus can induce life-threatening lymphoid and epithelial malignancies, accounting for approximately 150,000 deaths annually [35, 36].

EBV is transmitted from person to person through salivary exchange. However, the details of the early steps in EBV infection remain unclear. Two models have been proposed. In the first model, it is suggested that EBV initially infects tonsillar epithelial cells where it undergoes lytic replication with subsequent infection of B-lymphocytes. In the second model, it is suggested that EBV directly infects B-lymphocytes without the involvement of epithelial cells [37, 38]. Whatever the initial cellular target, one thing is fairly well-established; the cellular site of long-term EBV persistence is B-lymphocytes [39, 40]. These cells can be transformed and immortalized by EBV when grown in *in vitro* cultures, forming what are known as lymphoblastoid cell lines (LCLs). In LCLs, a number of viral latent products, namely 2 EBV encoded RNAs (EBER 1 and 2), 6 EBV nuclear antigens (EBNAs 1, 2, 3A, 3B, 3C and LP) and 3 EBV latent membrane proteins (LMPs 1, 2A and 2B) are expressed [33]. The expression of these latent products in infected cells is referred to as EBV latency III program and is typically observed in EBV associated post-transplant lymphomas [41] and in IM [42]. When EBERs, EBNA-1, LMP1 and LMP2 are expressed, it is known as latency II, typically seen in EBV associated Hodgkin's lymphoma. In latency I, only EBERs and EBNA-1 are expressed, as seen in Burkitt's lymphoma. In latently infected asymptomatic EBV carriers (>90% of the population), infected B cells express EBERs only [43]. Since no viral proteins are expressed in these cells, the virus can remain out of the radar of the host immune system. This strategy allows the virus to be dormant, but still dangerous. Moreover, the virus utilizes an array of viral encoded miRNAs to target immune associated mRNAs, aiding its escape from host defenses [44, 45]. Thus, EBV has evolved to be a master manipulator of the immune system, ensuring its persistence

for the life of its host, even in the face of a competent immune system.

immune response against myelin self-antigens in MS remain unknown.

**3. Epidemiological link between EBV and MS**

Beside the latent infection described above, a lytic infection can occasionally occur resulting in production of new virions. The expression of the immediate early lytic protein BZLF1 signals the beginning of the lytic cycle. Whether it is latent or lytic infection, an efficiently functioning immune system is essential to keep EBV infection under control and maintain a homeostatic virus-host relationship [46]. Thus, any disruption of the intricate connection between EBV and the immune system can lead to serious health conditions, for instance EBV-induced malignancies and some autoimmune disorders such as MS. Based on an accumulating body of evidence from epidemiological, serological and postmortem studies, it is now widely believed that EBV is associated, directly or indirectly in the pathogenesis of MS [20–22]**.** However, the details of how EBV induces or promotes an aberrant

A considerable amount of literature has been published on the link between the epidemiology of MS and EBV infection. Early reports consistently showed higher prevalence of EBV infection in MS patients compared to the general population [47, 48]. This difference was particularly pronounced in the pediatric cohort, where almost 100% of children with MS were EBV seropositive compared to 72% matched controls [49–52]. Consistent with these findings, MS risk was found to diminish in individuals who have never been exposed to EBV infection (the odds ratio of developing MS is 0.06 in a seronegative person compared to 13.5 in an EBV seropositive person). Furthermore, continuing to be EBV seronegative keeps MS risk to about

#### *Epstein-Barr Virus in Multiple Sclerosis DOI: http://dx.doi.org/10.5772/intechopen.85222*

*Multiple Sclerosis*

**1.1 Environmental risk factors for MS**

In support of the above observations, MS prevalence has been reported to be higher in the northern hemisphere, but lower towards the equator. However, recent studies indicate that this pattern of distribution, known as the latitudinal gradient, is changing in some countries such as Norway and USA [10–12]. Moreover, migration studies indicate that the increasing burden of MS is due to exposure to certain factors in the environment, which may account for a bigger proportion of MS risk than genetic factors. These studies show that leaving countries with high MS incidence prior to reaching adolescence, to regions with low MS incidence, confers protection against developing the disease [13]. Similarly, migrating in the opposite direction is linked to increased risk of developing MS [14–16]. These protective and MS predisposing effects have been shown to occur in a single generation, and this is highly unlikely to be due to

Additionally, exposure to specific environmental agents at a young age seems to be critical in shaping the risk of developing MS [18]. The past few decades have seen a rapid accumulation of epidemiological data pointing to a number of different environmental factors that could potentially be involved in MS pathogenesis. However, no single causative agent has yet been unequivocally shown to be central to MS development [19]. Environmental risk factors associated with MS include sunlight exposure and serum levels of vitamin D, smoking, obesity, female sex hormones, and infection with Epstein-Barr virus (EBV) [20–22]. Among these factors, infection with EBV, particularly when manifested as infectious mononucleosis (IM), appears to have the most significant and consistent association with the risk of developing MS [23].

The notion that an infectious agent is involved in the pathogenesis of MS is not new. A number of observations, including MS outbreak in the Faroes islands during World War II, which coincided with the British occupation of the islands [24], and MS occurrence in clustering fashion (e.g. familial clustering of MS), suggested an infectious cause for MS [17]. The hygiene hypothesis was used to provide an explanation for such involvement [21], assuming that certain infections occurring during the first few years of life can protect against MS, whereas exposure to the same infections later in life, predisposes to MS [25]. The hygiene hypothesis also partly explained the geographical distribution of MS, in that it is less common in tropical regions that are known to be endemic to certain microbial infections. In these areas, children tend to acquire infections very early in life [26, 27]. Similarly, MS incidence seems to rise in tropical regions [28] that have witnessed improved feasibility of vaccines and antibiotics and enhanced sanitary conditions which have led to decreased childhood infections [29–31]. However, some epidemiological observations such as the finding that the risk of MS in individuals who have never been exposed to EBV is 10 fold lower than in those who were exposed to childhood

effects of genes which usually manifest on longer periods of time [17].

**1.2 Infectious risk factors for MS: Hygiene hypothesis**

EBV infection [32], cannot be explained by the hygiene hypothesis.

EBV is a common human herpesvirus, infecting over 90% of the population worldwide [33]. Generally, EBV infection is considered to be one of the early asymptomatic childhood infections and in the vast majority of the infected individuals, the virus persists for life without causing disease. Bizarrely, if primary infection is delayed until adolescence, as commonly noted in developed countries, the virus can

**2. Epstein-Barr virus (EBV)**

**102**

cause an acute self-limiting symptomatic infection known as infectious mononucleosis (IM) [34]. Importantly, EBV has oncogenic properties and in a very small percentage of individuals, the virus can induce life-threatening lymphoid and epithelial malignancies, accounting for approximately 150,000 deaths annually [35, 36].

EBV is transmitted from person to person through salivary exchange. However, the details of the early steps in EBV infection remain unclear. Two models have been proposed. In the first model, it is suggested that EBV initially infects tonsillar epithelial cells where it undergoes lytic replication with subsequent infection of B-lymphocytes. In the second model, it is suggested that EBV directly infects B-lymphocytes without the involvement of epithelial cells [37, 38]. Whatever the initial cellular target, one thing is fairly well-established; the cellular site of long-term EBV persistence is B-lymphocytes [39, 40]. These cells can be transformed and immortalized by EBV when grown in *in vitro* cultures, forming what are known as lymphoblastoid cell lines (LCLs). In LCLs, a number of viral latent products, namely 2 EBV encoded RNAs (EBER 1 and 2), 6 EBV nuclear antigens (EBNAs 1, 2, 3A, 3B, 3C and LP) and 3 EBV latent membrane proteins (LMPs 1, 2A and 2B) are expressed [33]. The expression of these latent products in infected cells is referred to as EBV latency III program and is typically observed in EBV associated post-transplant lymphomas [41] and in IM [42]. When EBERs, EBNA-1, LMP1 and LMP2 are expressed, it is known as latency II, typically seen in EBV associated Hodgkin's lymphoma. In latency I, only EBERs and EBNA-1 are expressed, as seen in Burkitt's lymphoma. In latently infected asymptomatic EBV carriers (>90% of the population), infected B cells express EBERs only [43]. Since no viral proteins are expressed in these cells, the virus can remain out of the radar of the host immune system. This strategy allows the virus to be dormant, but still dangerous. Moreover, the virus utilizes an array of viral encoded miRNAs to target immune associated mRNAs, aiding its escape from host defenses [44, 45]. Thus, EBV has evolved to be a master manipulator of the immune system, ensuring its persistence for the life of its host, even in the face of a competent immune system.

Beside the latent infection described above, a lytic infection can occasionally occur resulting in production of new virions. The expression of the immediate early lytic protein BZLF1 signals the beginning of the lytic cycle. Whether it is latent or lytic infection, an efficiently functioning immune system is essential to keep EBV infection under control and maintain a homeostatic virus-host relationship [46]. Thus, any disruption of the intricate connection between EBV and the immune system can lead to serious health conditions, for instance EBV-induced malignancies and some autoimmune disorders such as MS. Based on an accumulating body of evidence from epidemiological, serological and postmortem studies, it is now widely believed that EBV is associated, directly or indirectly in the pathogenesis of MS [20–22]**.** However, the details of how EBV induces or promotes an aberrant immune response against myelin self-antigens in MS remain unknown.

## **3. Epidemiological link between EBV and MS**

A considerable amount of literature has been published on the link between the epidemiology of MS and EBV infection. Early reports consistently showed higher prevalence of EBV infection in MS patients compared to the general population [47, 48]. This difference was particularly pronounced in the pediatric cohort, where almost 100% of children with MS were EBV seropositive compared to 72% matched controls [49–52]. Consistent with these findings, MS risk was found to diminish in individuals who have never been exposed to EBV infection (the odds ratio of developing MS is 0.06 in a seronegative person compared to 13.5 in an EBV seropositive person). Furthermore, continuing to be EBV seronegative keeps MS risk to about

10-fold lower than those who seroconvert [53] and about 20-fold less than those with a history of IM, the primary symptomatic EBV infection [32]. These reports suggest that the risk of MS rises in EBV-seronegative individuals soon after they seroconvert as confirmed by a nested case–control study on 305 MS cases and 610 controls [54].

Interestingly, IM has a strikingly similar distribution to that of MS [55]. Moreover, females report IM symptoms earlier (more prolonged), more frequently, and with more severity than their male counterparts. Females also tend to have higher anti-EBV titers and are believed to mount stronger response against EBV [56, 57]. In demonstration of the correlation between IM and the risk of MS, a case–control study found that history of IM increases the risk of developing a CNS demyelinating disease, particularly in genetically susceptible individuals who are HLA-DRB1\*1501 positive [58]. In support of these results, a meta-analysis of 14 case–control and longitudinal studies reported that history of IM significantly increased the risk of MS by over 2 folds [59]. Furthermore, this increased risk persists for at least 30 years post EBV infection [60], suggesting that symptomatic EBV infection manifested as IM may be a prerequisite to developing the autoimmune response associated with MS [61].

## **4. Serological link between EBV and MS**

More evidence has been brought to light by serological studies investigating antibody response against EBV antigens in MS patients compared to that in controls. One of the most consist piece of evidence is the finding of elevated antibody titers against EBNA-1 antigen in the blood, both pre- and post-onset of the disease [62–65]. Indeed, individuals with clinically isolated syndromes (CIS) are more likely to develop definite MS when they experience elevated antibody response to EBNA-1 [66, 67]. Furthermore, serum levels of anti-EBV capsid antigen (VCA) together with anti-EBNA-1 IgG antibodies seem to also correlate with the risk of MS [68]. In an attempt to understand how the humoral response towards EBNA-1 impacts the risk of developing MS, it was shown that the levels of circulating IgG against certain EBNA-1 epitopes, particularly those derived from EBNA-1: 385–420 domain, interact with MS risk gene, the HLA genotype DRB1\*15 in amplifying MS risk [69]. These findings point to similarities between how HLA molecules influence response to EBV antigens and how they are involved in inducing autoimmune response [70]. Additionally, the humoral response to EBV antigens, specifically anti-EBNA-1 IgG vary between different forms of MS, namely CIS, relapsing–remitting and progressive MS [71], suggesting that the level of these antibodies is not only predictive of MS onset, but also of disease progression. However, it remains debatable whether the humoral level can correlate with markers of disease progression such as volumes of T2 MRI lesions, reflective of demyelinative disease activity and scores of Expanded Disability Status Scale (EDSS), reflective of the progression of physical disability [71–76]. Despite some of these inconsistencies in the serological link between EBV infection and MS, studies agree on the fact that serum antibody titers to EBNA-1 increase prior to developing MS, and hence predictive of MS. In other words, it seems that EBV acts early in provoking an immune (humoral) response towards promoting the onset of MS [77]. However, it is safe to argue that EBV may be a cofactor contributing with other factors, such as genetic susceptibility and vitamin D levels, to the pathogenesis of MS [78, 79].

## **5. Cellular immune response to EBV in MS**

Forty years ago, it was shown that peripheral blood mononuclear cells (PBMCs) taken from patients with active MS, spontaneously transformed into LCLs in *in vitro*

**105**

*Epstein-Barr Virus in Multiple Sclerosis DOI: http://dx.doi.org/10.5772/intechopen.85222*

culture more readily than PBMCs taken from healthy controls or patients with inactive MS [80]. These spontaneously immortalized LCLs were of B-cell origin and expressed EBV antigens, including VCA and EBNAs [80]. So, why do PBMCs from active MS patients transform more readily compared to those from healthy controls? One possible explanation is that the immune response to EBV in MS patients is less effective compared to healthy EBV seropositive individuals. Indeed, data from a number of different studies indicates that the T-cell response to EBV is aberrantly regulated in MS patients and it varies at different stages of the disease [81–83]. CD8+ T cells in the blood of MS patients with inactive disease, have been shown to express the immune inhibitory molecule, programmed death 1 (PD-1), making these cells

believed to be a common feature in many chronic viral infections [85–87], and could explain the conflicting results in EBV viral load detected in MS patients. Thus, the stage of the disease and the level of T cell exhaustion could account for the higher viral load reported in some studies [88, 89], whilst others showed no statistical difference between MS and controls [89–91]. Further support for an aberrant anti-viral immune response in MS comes from the observations that MS patients appear to be at increased risk of acquiring certain viral infections such as influenza [92, 93].

A more recent study investigated B cell transformation of PBMCs taken from 21 MS patients and 21 healthy controls [94]. In order to minimize the effect of T cell control of EBV, which may vary from person to person, T cell activity in all PBMCs cultures was inhibited using cyclosporine A. Cultures obtained from MS patients resulted in significantly higher frequency of B cell transformation compared to healthy controls [94]. Whether this was due to MS patients having a higher frequency of circulating EBV infected cells, or due to higher frequency of viral lytic

There have also been some attempts to examine differences in the cell-mediated immune response against EBV and its antigens in the blood and cerebrospinal fluid (CSF) of MS patients [95, 96]. However, these investigations have also yielded inconsistent results. Whilst some have reported an increase in frequency of both

of common autoantigens suspected to be targets of immune response in MS [97]. Thus, the identity of the target antigen for the autoreactive T cells remains elusive.

positive MS patients reacted with GDP-L-fucose synthase, an enzyme frequently expressed in human cells as well as in bacteria commonly present in the gastrointestinal track of MS patients [98]. This tantalizing finding warrants further investigations to determine if gut bacterial GDP-L-fucose synthase is indeed the primary trigger for the activation of autoreactive T-cells that subsequently migrate to the brain and lead to demyelination. It is plausible that EBV could also trigger autoreactive T-cells by molecularly mimicry [99–101]. In this context, certain epitopes of EBNA-1, EBNA-3A and LMP2 have been shown to be targets of CD8+

cell responses and to cross-react with self-antigens associated with MS pathogenesis [102–104]. However, current evidence fails to clearly explain how cell-mediated

Compared to the blood and CSF, access to brain tissues, particularly fresh tissues from MS patients has been difficult and limited. In spite of this, a number of studies

**6. Direct demonstration of the presence of EBV in MS brains**

T cells in MS [96], others have found that

T cells from HLA-DRB3

T

T cells from MS failed to react to a number

T cells are increased compared to controls [95].

and CD8+

and CD8+

A very recent study has reported that intrathecal CD4+

immune responses to EBV antigens may lead to MS.

T cell exhaustion is

less efficient in eliminating EBV infected cells [84]. This CD8+

replication occurring in MS patients is not clear.

intrathecal EBV reactive CD4<sup>+</sup>

Moreover, intrathecal CD4+

T cells and not CD4<sup>+</sup>

only CD8+

#### *Epstein-Barr Virus in Multiple Sclerosis DOI: http://dx.doi.org/10.5772/intechopen.85222*

*Multiple Sclerosis*

10-fold lower than those who seroconvert [53] and about 20-fold less than those with a history of IM, the primary symptomatic EBV infection [32]. These reports suggest that the risk of MS rises in EBV-seronegative individuals soon after they seroconvert as confirmed by a nested case–control study on 305 MS cases and 610 controls [54]. Interestingly, IM has a strikingly similar distribution to that of MS [55]. Moreover, females report IM symptoms earlier (more prolonged), more frequently, and with more severity than their male counterparts. Females also tend to have higher anti-EBV titers and are believed to mount stronger response against EBV [56, 57]. In demonstration of the correlation between IM and the risk of MS, a case–control study found that history of IM increases the risk of developing a CNS demyelinating disease, particularly in genetically susceptible individuals who are HLA-DRB1\*1501 positive [58]. In support of these results, a meta-analysis of 14 case–control and longitudinal studies reported that history of IM significantly increased the risk of MS by over 2 folds [59]. Furthermore, this increased risk persists for at least 30 years post EBV infection [60], suggesting that symptomatic EBV infection manifested as IM may be a

prerequisite to developing the autoimmune response associated with MS [61].

More evidence has been brought to light by serological studies investigating antibody response against EBV antigens in MS patients compared to that in controls. One of the most consist piece of evidence is the finding of elevated antibody titers against EBNA-1 antigen in the blood, both pre- and post-onset of the disease [62–65]. Indeed, individuals with clinically isolated syndromes (CIS) are more likely to develop definite MS when they experience elevated antibody response to EBNA-1 [66, 67]. Furthermore, serum levels of anti-EBV capsid antigen (VCA) together with anti-EBNA-1 IgG antibodies seem to also correlate with the risk of MS [68]. In an attempt to understand how the humoral response towards EBNA-1 impacts the risk of developing MS, it was shown that the levels of circulating IgG against certain EBNA-1 epitopes, particularly those derived from EBNA-1: 385–420 domain, interact with MS risk gene, the HLA genotype DRB1\*15 in amplifying MS risk [69]. These findings point to similarities between how HLA molecules influence response to EBV antigens and how they are involved in inducing autoimmune response [70]. Additionally, the humoral response to EBV antigens, specifically anti-EBNA-1 IgG vary between different forms of MS, namely CIS, relapsing–remitting and progressive MS [71], suggesting that the level of these antibodies is not only predictive of MS onset, but also of disease progression. However, it remains debatable whether the humoral level can correlate with markers of disease progression such as volumes of T2 MRI lesions, reflective of demyelinative disease activity and scores of Expanded Disability Status Scale (EDSS), reflective of the progression of physical disability [71–76]. Despite some of these inconsistencies in the serological link between EBV infection and MS, studies agree on the fact that serum antibody titers to EBNA-1 increase prior to developing MS, and hence predictive of MS. In other words, it seems that EBV acts early in provoking an immune (humoral) response towards promoting the onset of MS [77]. However, it is safe to argue that EBV may be a cofactor contributing with other factors, such as genetic susceptibility and vitamin D levels, to the pathogenesis of MS [78, 79].

**4. Serological link between EBV and MS**

**5. Cellular immune response to EBV in MS**

Forty years ago, it was shown that peripheral blood mononuclear cells (PBMCs) taken from patients with active MS, spontaneously transformed into LCLs in *in vitro*

**104**

culture more readily than PBMCs taken from healthy controls or patients with inactive MS [80]. These spontaneously immortalized LCLs were of B-cell origin and expressed EBV antigens, including VCA and EBNAs [80]. So, why do PBMCs from active MS patients transform more readily compared to those from healthy controls? One possible explanation is that the immune response to EBV in MS patients is less effective compared to healthy EBV seropositive individuals. Indeed, data from a number of different studies indicates that the T-cell response to EBV is aberrantly regulated in MS patients and it varies at different stages of the disease [81–83]. CD8+ T cells in the blood of MS patients with inactive disease, have been shown to express the immune inhibitory molecule, programmed death 1 (PD-1), making these cells less efficient in eliminating EBV infected cells [84]. This CD8+ T cell exhaustion is believed to be a common feature in many chronic viral infections [85–87], and could explain the conflicting results in EBV viral load detected in MS patients. Thus, the stage of the disease and the level of T cell exhaustion could account for the higher viral load reported in some studies [88, 89], whilst others showed no statistical difference between MS and controls [89–91]. Further support for an aberrant anti-viral immune response in MS comes from the observations that MS patients appear to be at increased risk of acquiring certain viral infections such as influenza [92, 93].

A more recent study investigated B cell transformation of PBMCs taken from 21 MS patients and 21 healthy controls [94]. In order to minimize the effect of T cell control of EBV, which may vary from person to person, T cell activity in all PBMCs cultures was inhibited using cyclosporine A. Cultures obtained from MS patients resulted in significantly higher frequency of B cell transformation compared to healthy controls [94]. Whether this was due to MS patients having a higher frequency of circulating EBV infected cells, or due to higher frequency of viral lytic replication occurring in MS patients is not clear.

There have also been some attempts to examine differences in the cell-mediated immune response against EBV and its antigens in the blood and cerebrospinal fluid (CSF) of MS patients [95, 96]. However, these investigations have also yielded inconsistent results. Whilst some have reported an increase in frequency of both intrathecal EBV reactive CD4<sup>+</sup> and CD8+ T cells in MS [96], others have found that only CD8+ T cells and not CD4<sup>+</sup> T cells are increased compared to controls [95]. Moreover, intrathecal CD4+ and CD8+ T cells from MS failed to react to a number of common autoantigens suspected to be targets of immune response in MS [97]. Thus, the identity of the target antigen for the autoreactive T cells remains elusive. A very recent study has reported that intrathecal CD4+ T cells from HLA-DRB3 positive MS patients reacted with GDP-L-fucose synthase, an enzyme frequently expressed in human cells as well as in bacteria commonly present in the gastrointestinal track of MS patients [98]. This tantalizing finding warrants further investigations to determine if gut bacterial GDP-L-fucose synthase is indeed the primary trigger for the activation of autoreactive T-cells that subsequently migrate to the brain and lead to demyelination. It is plausible that EBV could also trigger autoreactive T-cells by molecularly mimicry [99–101]. In this context, certain epitopes of EBNA-1, EBNA-3A and LMP2 have been shown to be targets of CD8+ T cell responses and to cross-react with self-antigens associated with MS pathogenesis [102–104]. However, current evidence fails to clearly explain how cell-mediated immune responses to EBV antigens may lead to MS.

## **6. Direct demonstration of the presence of EBV in MS brains**

Compared to the blood and CSF, access to brain tissues, particularly fresh tissues from MS patients has been difficult and limited. In spite of this, a number of studies have examined brain tissues to explore the link between EBV and the pathogenesis of MS. Most of these investigations have been conducted on formalin-fixed, paraffinembedded post-mortem tissues. Arguably, these studies have generated the strongest and most convincing data implicating EBV in the development of MS. Initial attempts aimed at directly demonstrating if EBV was present in MS lesions or not, reported either negative results or did not see any difference in EBV positivity between MS and control tissues [105, 106]. A subsequent study however, reported the presence of EBV in 21/22 MS, but not in non-MS inflammatory neurological conditions [107]. The virus was localized to B cells and plasma cells, most notably in the meninges and perivascular infiltrates of active lesions. Additionally, infected cells were found to express a number of viral antigens, latent and lytic [107], making them a potential target of CD8+ T cells and triggering an inflammatory environment in the CNS [82]. Although these findings were confirmed by some subsequent studies [108, 109], others reported absence of EBV infection in the MS brain [110–112]. It was argued that the discrepancies in the findings would be due to many different variables, including differences in the tissue samples examined, variation in tissue preservation and processing, type of fixatives and length of fixation, and the sensitivity and specificity of methods used for EBV detection [113]. Moreover, owing to the great heterogeneity of the brain, the molecular and cellular environment of one region does not necessarily represent another adjacent region, even in the same tissue block [113, 114]. Thus, the absence of EBV in one region of the brain, cannot be interpreted to mean that the virus is absent from all parts of the brain. Keeping some of these variables in mind, we recently conducted an extensive study examining the potential involvement of EBV in MS pathogenesis [115]. We analyzed over 1000 samples from MS cases and non-MS controls using our highly sensitive EBER-*in situ* hybridization, PCR, and immunohistochemistry methodologies [115]. Our findings indicated that EBV was present in most (90%) cases of MS and the virus could be detected in multiple tissue samples from each case. Surprisingly, we found EBV not only in B-cells, but also in astrocytes and some microglial cells. Significantly, the virus was transcriptionally active in these cells and expressed EBNA-1, and to a lesser extent the early lytic cycle protein BZLF1. Taken together, these findings support a role for EBV in the pathogenesis of MS.

## **7. Proposed model of EBV involvement in MS pathology**

The data demonstrating the presence of EBV directly in the brain of MS cases is fairly robust and convincing evidence in support of a role for EBV in the pathogenesis of MS. However, the presence of the virus in the brain cannot be simply interpreted to imply causality. Although it is possible that EBV infection could be a consequence of MS pathology, the observation that EBV seronegative individuals have an almost zero risk of developing MS is strong and compelling evidence supporting a role for EBV in initiating MS. Ironically, although it is believed that T-cells orchestrate and lead the pathogenesis of MS, treatment strategies that have been shown to be most effective in controlling disease activity, involve depleting B-cells [22, 116]. Moreover, depleting memory B-cells, the very cells that harbor EBV, appears to be the most effective [117]. How can these apparently contradictory findings be reconciled? We propose that EBV infected memory B-cells act as antigen presenting cells (APC), resulting in the activation of helper T-cells, which in individuals carrying certain HLA haplotypes, activate autoreactive B and T-cells targeting antigens expressed on oligodendrocytes [102, 118]. In this model (**Figure 1**), disturbances in the integrity of the blood brain barrier (BBB) allows EBV carrying memory B-cells to cross into the CNS, triggering a cascade of events including, attraction of autoreactive B and T-cells, triggering pro-inflammatory

**107**

**Figure 1.**

*Epstein-Barr Virus in Multiple Sclerosis DOI: http://dx.doi.org/10.5772/intechopen.85222*

cytokines and microglial activation [118–120]. While most of the EBV infected B-cells infiltrating into the brain remain latently infected, a small percentage are triggered to undergo lytic replication [121, 122, 107], which could explain how CNS resident astrocytes and microglial cells get infected [115]. Infection of astrocytes can be reconciled by the fact that, like B-cells, they also express CD21, the receptor for EBV [123]. Astrocytes are the most abundant cells in the CNS, constituting around 30% of the total cells. They play an important role in a number of homeostatic and neuroinflammatory processes within the CNS, including axon guidance, synaptic transmission and controlling BBB [124, 125]. An accumulating body of data now indicates that activated astrocytes also play a central role in neurodegenerative diseases such as MS [124–126]. Since astrocytes interact with blood vessels to form the BBB, any functional impact on these cells could also increase BBB permeability and exacerbate infiltration of peripheral immune cells into the CNS [120, 125, 127]. This could explain the characteristic perivascular cuffing and presence of inflammatory aggregates resembling germinal center (GC)-like structures commonly observed in the CNS in viral infections [22, 128]. Although the precise role of these tertiary lymphoid aggregates remains unknown, it is likely that they play a key role

*Model for EBV involvement in MS pathology. The pathogenesis of MS is no doubt very complex. This is a simplified outline of a potential model to explain some of the experimental findings linking EBV to MS. EBV persists in memory B-cells in peripheral circulation [39, 40] and in healthy seropositive individuals, they are tightly regulated by the immune system. In individuals genetically predisposed to MS, these cells cross the BBB and enter the CNS where they trigger an inflammatory response leading to the formation of GC-like structures [128, 129]. Most of the infected cells remain latently infected with limited viral gene expression [107, 108]. These infected cells could function as APC for the activation of helper T-cells [118] which in individuals carrying certain HLA haplotypes [89, 132], leads to the activation of autoreactive B and T-cells that recognize both EBV and self-antigens [99, 101, 118]. A small proportion of EBV infected memory B-cells, upon differentiation into plasma cells, initiate EBV replicative cycle [121, 122]. The new virions produced, infect other susceptible cells, including astrocytes and microglia [115, 123]. Microglia and astrocytes are two main types of cells typically providing a protective role against viral infection. In their activated form, they release various pro-inflammatory cytokines and immune mediators that activate the immune system to resolve the infection [125, 133]. In MS, these chronically activated cells switch from being neuroprotective to neurotoxic [133, 134]. Additionally, proinflammatory microglia can also induce activation of astrocytes, which can impact not only the BBB but also contribute to neurotoxicity [125, 126]. The combined effects of these multiple events result in MS pathology.*

## *Epstein-Barr Virus in Multiple Sclerosis DOI: http://dx.doi.org/10.5772/intechopen.85222*

*Multiple Sclerosis*

CD8+

have examined brain tissues to explore the link between EBV and the pathogenesis of MS. Most of these investigations have been conducted on formalin-fixed, paraffinembedded post-mortem tissues. Arguably, these studies have generated the strongest and most convincing data implicating EBV in the development of MS. Initial attempts aimed at directly demonstrating if EBV was present in MS lesions or not, reported either negative results or did not see any difference in EBV positivity between MS and control tissues [105, 106]. A subsequent study however, reported the presence of EBV in 21/22 MS, but not in non-MS inflammatory neurological conditions [107]. The virus was localized to B cells and plasma cells, most notably in the meninges and perivascular infiltrates of active lesions. Additionally, infected cells were found to express a number of viral antigens, latent and lytic [107], making them a potential target of

 T cells and triggering an inflammatory environment in the CNS [82]. Although these findings were confirmed by some subsequent studies [108, 109], others reported absence of EBV infection in the MS brain [110–112]. It was argued that the discrepancies in the findings would be due to many different variables, including differences in the tissue samples examined, variation in tissue preservation and processing, type of fixatives and length of fixation, and the sensitivity and specificity of methods used for EBV detection [113]. Moreover, owing to the great heterogeneity of the brain, the molecular and cellular environment of one region does not necessarily represent another adjacent region, even in the same tissue block [113, 114]. Thus, the absence of EBV in one region of the brain, cannot be interpreted to mean that the virus is absent from all parts of the brain. Keeping some of these variables in mind, we recently conducted an extensive study examining the potential involvement of EBV in MS pathogenesis [115]. We analyzed over 1000 samples from MS cases and non-MS controls using our highly sensitive EBER-*in situ* hybridization, PCR, and immunohistochemistry methodologies [115]. Our findings indicated that EBV was present in most (90%) cases of MS and the virus could be detected in multiple tissue samples from each case. Surprisingly, we found EBV not only in B-cells, but also in astrocytes and some microglial cells. Significantly, the virus was transcriptionally active in these cells and expressed EBNA-1, and to a lesser extent the early lytic cycle protein BZLF1. Taken together, these findings support a role for EBV in the pathogenesis of MS.

**7. Proposed model of EBV involvement in MS pathology**

The data demonstrating the presence of EBV directly in the brain of MS cases is fairly robust and convincing evidence in support of a role for EBV in the pathogenesis of MS. However, the presence of the virus in the brain cannot be simply interpreted to imply causality. Although it is possible that EBV infection could be a consequence of MS pathology, the observation that EBV seronegative individuals have an almost zero risk of developing MS is strong and compelling evidence supporting a role for EBV in initiating MS. Ironically, although it is believed that T-cells orchestrate and lead the pathogenesis of MS, treatment strategies that have been shown to be most effective in controlling disease activity, involve depleting B-cells [22, 116]. Moreover, depleting memory B-cells, the very cells that harbor EBV, appears to be the most effective [117]. How can these apparently contradictory findings be reconciled? We propose that EBV infected memory B-cells act as antigen presenting cells (APC), resulting in the activation of helper T-cells, which in individuals carrying certain HLA haplotypes, activate autoreactive B and T-cells targeting antigens expressed on oligodendrocytes [102, 118]. In this model (**Figure 1**), disturbances in the integrity of the blood brain barrier (BBB) allows EBV carrying memory B-cells to cross into the CNS, triggering a cascade of events including, attraction of autoreactive B and T-cells, triggering pro-inflammatory

**106**

cytokines and microglial activation [118–120]. While most of the EBV infected B-cells infiltrating into the brain remain latently infected, a small percentage are triggered to undergo lytic replication [121, 122, 107], which could explain how CNS resident astrocytes and microglial cells get infected [115]. Infection of astrocytes can be reconciled by the fact that, like B-cells, they also express CD21, the receptor for EBV [123]. Astrocytes are the most abundant cells in the CNS, constituting around 30% of the total cells. They play an important role in a number of homeostatic and neuroinflammatory processes within the CNS, including axon guidance, synaptic transmission and controlling BBB [124, 125]. An accumulating body of data now indicates that activated astrocytes also play a central role in neurodegenerative diseases such as MS [124–126]. Since astrocytes interact with blood vessels to form the BBB, any functional impact on these cells could also increase BBB permeability and exacerbate infiltration of peripheral immune cells into the CNS [120, 125, 127]. This could explain the characteristic perivascular cuffing and presence of inflammatory aggregates resembling germinal center (GC)-like structures commonly observed in the CNS in viral infections [22, 128]. Although the precise role of these tertiary lymphoid aggregates remains unknown, it is likely that they play a key role

#### **Figure 1.**

*Model for EBV involvement in MS pathology. The pathogenesis of MS is no doubt very complex. This is a simplified outline of a potential model to explain some of the experimental findings linking EBV to MS. EBV persists in memory B-cells in peripheral circulation [39, 40] and in healthy seropositive individuals, they are tightly regulated by the immune system. In individuals genetically predisposed to MS, these cells cross the BBB and enter the CNS where they trigger an inflammatory response leading to the formation of GC-like structures [128, 129]. Most of the infected cells remain latently infected with limited viral gene expression [107, 108]. These infected cells could function as APC for the activation of helper T-cells [118] which in individuals carrying certain HLA haplotypes [89, 132], leads to the activation of autoreactive B and T-cells that recognize both EBV and self-antigens [99, 101, 118]. A small proportion of EBV infected memory B-cells, upon differentiation into plasma cells, initiate EBV replicative cycle [121, 122]. The new virions produced, infect other susceptible cells, including astrocytes and microglia [115, 123]. Microglia and astrocytes are two main types of cells typically providing a protective role against viral infection. In their activated form, they release various pro-inflammatory cytokines and immune mediators that activate the immune system to resolve the infection [125, 133]. In MS, these chronically activated cells switch from being neuroprotective to neurotoxic [133, 134]. Additionally, proinflammatory microglia can also induce activation of astrocytes, which can impact not only the BBB but also contribute to neurotoxicity [125, 126]. The combined effects of these multiple events result in MS pathology.*

in the immune response to CNS injury [129]. In contrast to previously held views, studies now indicate that B-cell differentiation and clonal expansion typically known to occur in secondary lymphoid organs, can also occur in the CNS [130]. This finding also provides an explanation for the source of oligoclonal immunoglobulin bands present in the CSF of most patients with MS. In MS, these GC-like aggregates, triggered by EBV infection of the brain, could be responsible for recruiting, activating and sustaining B and T-cells [119, 118] that inadvertently react to auto-antigens, such as myelin basic protein (MBP) and GDP-L-fucose synthase, expressed on oligodendrocytes (**Figure 1**) [98, 99, 101]. Moreover, cellular and viral components such miRNAs and EBERs, secreted in exosomes could also promote inflammatory and pathological changes that contribute to CNS injury in MS [108, 131].

## **8. Conclusion**

The pathogenesis of MS appears to be a complex process, where both genetic and environmental risk factors interplay to promote the development of the disease. The evidence implicating EBV as a central player in MS development is substantial. For some critics, these pieces of evidence are still not sufficient to charge EBV as the mastermind behind the pathogenesis of MS. A very recent study by Pender and colleagues goes some way to proving the etiological association [135]. The study demonstrated that treating MS patients with autologous EBV-specific T cell therapy can improve symptoms and quality of life in most patients [135]. The only absolute and unequivocal proof that EBV is central to the development of MS, is to prevent EBV infection in the first place by vaccination and then see if the incidence of MS declines. Although a number of vaccine candidates have been tested, none have yet been approved for clinical use [136].

## **Acknowledgements**

This work was supported by UAEU grants (31 M376 & 31 R135) awarded to GK and PhD Scholarship awarded to AH from UAE University.

## **Conflict of interest**

The authors have no conflict of interest.

## **Author details**

Gulfaraz Khan\* and Asma Hassani Department of Microbiology and Immunology, College of Medicine and Health Sciences, Tawam Hospital Campus, United Arab Emirates University, Al Ain, UAE

\*Address all correspondence to: g\_khan@uaeu.ac.ae

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**109**

2014;**2014**:124578

[11] Melcon MO, Correale J,

*Epstein-Barr Virus in Multiple Sclerosis DOI: http://dx.doi.org/10.5772/intechopen.85222*

[1] Compston A, Coles A. Multiple sclerosis. Lancet. 2008;**372**:1502-1517 classification of multiple sclerosis? Journal of the Neurological Sciences.

[12] Koch-Henriksen N, Sørensen PS. The changing demographic pattern of multiple sclerosis epidemiology. Lancet

[13] Berg-Hansen P, Celius EG. Socioeconomic factors and immigrant population studies of multiple sclerosis.

Acta Neurologica Scandinavica.

[14] Nasr Z, Majed M, Rostami A, et al. Prevalence of multiple sclerosis in Iranian emigrants: Review of the evidence. Neurological Sciences.

[15] Ahlgren C, Lycke J, Odén A, et al. High risk of MS in Iranian immigrants in Gothenburg, Sweden. Multiple Sclerosis. 2010;**16**:1079-1082

Sandvik L, et al. Prevalence of multiple sclerosis among immigrants in Norway. Multiple Sclerosis. 2015;**21**:695-702

[17] Milo R, Kahana E. Multiple sclerosis: Geoepidemiology, genetics and the environment. Autoimmunity Reviews.

[16] Berg-Hansen P, Moen SM,

[18] McLeod JG, Hammond SR, Kurtzke JF. Migration and multiple sclerosis in immigrants to Australia from United Kingdom and Ireland: A reassessment. I. Risk of MS by age at immigration. Journal of Neurology.

Neurology. 2010;**9**:520-532

2014;**344**:171-181

2015;**132**:37-41

2016;**37**:1759-1763

2010;**9**:A387-A394

2011;**258**:1140-1149

[19] Ascherio A, Munger KL.

[20] Ascherio A, Munger KL, Lünemann JD. The initiation and

Environmental risk factors for multiple sclerosis. Part II: Noninfectious factors. Annals of Neurology. 2007;**61**:504-513

[2] Baranzini SE, Oksenberg JR. The genetics of multiple sclerosis: From 0 to 200 in 50 years. Trends in Genetics.

[3] Gourraud P-A, Harbo HF, Hauser SL, et al. The genetics of multiple sclerosis: An up-to-date review. Immunological

[5] Rosati G. The prevalence of multiple sclerosis in the world: An update. Neurological Sciences. 2001;**22**:117-139

**References**

2017;**33**:960-970

Reviews. 2012;**248**:87-103

[4] Dilokthornsakul P, Valuck RJ, Nair KV, et al. Multiple sclerosis prevalence in the United States commercially insured population. Neurology. 2016;**86**:1014-1021

[6] Wallin MT, Culpepper WJ, Coffman P, et al. The gulf war era multiple sclerosis cohort: Age and incidence rates by race, sex and service.

[7] Langer-Gould A, Brara SM,

[8] Compston A. The genetic epidemiology of multiple sclerosis. Philosophical Transactions of the Royal Society of London. Series B, Biological

Sciences. 1999;**354**:1623-1634

[9] Hansen T, Skytthe A, Stenager E, et al. Risk for multiple sclerosis in dizygotic and monozygotic twins. Multiple Sclerosis. 2005;**11**:500-503

[10] Wade BJ. Spatial analysis of global prevalence of multiple sclerosis suggests need for an updated prevalence scale. Multiple Sclerosis International.

Melcon CM. Is it time for a new global

Beaber BE, et al. Incidence of multiple sclerosis in multiple racial and ethnic groups. Neurology. 2013;**80**:1734-1739

Brain. 2012;**135**:1778-1785

*Epstein-Barr Virus in Multiple Sclerosis DOI: http://dx.doi.org/10.5772/intechopen.85222*

## **References**

*Multiple Sclerosis*

**8. Conclusion**

**Acknowledgements**

**Conflict of interest**

**Author details**

**108**

provided the original work is properly cited.

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Department of Microbiology and Immunology, College of Medicine and Health Sciences, Tawam Hospital Campus, United Arab Emirates University, Al Ain, UAE

in the immune response to CNS injury [129]. In contrast to previously held views, studies now indicate that B-cell differentiation and clonal expansion typically known to occur in secondary lymphoid organs, can also occur in the CNS [130]. This finding also provides an explanation for the source of oligoclonal immunoglobulin bands present in the CSF of most patients with MS. In MS, these GC-like aggregates, triggered by EBV infection of the brain, could be responsible for recruiting, activating and sustaining B and T-cells [119, 118] that inadvertently react to auto-antigens, such as myelin basic protein (MBP) and GDP-L-fucose synthase, expressed on oligodendrocytes (**Figure 1**) [98, 99, 101]. Moreover, cellular and viral components such miRNAs and EBERs, secreted in exosomes could also promote inflammatory

and pathological changes that contribute to CNS injury in MS [108, 131].

The pathogenesis of MS appears to be a complex process, where both genetic and environmental risk factors interplay to promote the development of the disease. The evidence implicating EBV as a central player in MS development is substantial. For some critics, these pieces of evidence are still not sufficient to charge EBV as the mastermind behind the pathogenesis of MS. A very recent study by Pender and colleagues goes some way to proving the etiological association [135]. The study demonstrated that treating MS patients with autologous EBV-specific T cell therapy can improve symptoms and quality of life in most patients [135]. The only absolute and unequivocal proof that EBV is central to the development of MS, is to prevent EBV infection in the first place by vaccination and then see if the incidence of MS declines. Although a number of vaccine candidates have been tested, none have yet been approved for clinical use [136].

This work was supported by UAEU grants (31 M376 & 31 R135) awarded to GK

and PhD Scholarship awarded to AH from UAE University.

The authors have no conflict of interest.

\*Address all correspondence to: g\_khan@uaeu.ac.ae

Gulfaraz Khan\* and Asma Hassani

[1] Compston A, Coles A. Multiple sclerosis. Lancet. 2008;**372**:1502-1517

[2] Baranzini SE, Oksenberg JR. The genetics of multiple sclerosis: From 0 to 200 in 50 years. Trends in Genetics. 2017;**33**:960-970

[3] Gourraud P-A, Harbo HF, Hauser SL, et al. The genetics of multiple sclerosis: An up-to-date review. Immunological Reviews. 2012;**248**:87-103

[4] Dilokthornsakul P, Valuck RJ, Nair KV, et al. Multiple sclerosis prevalence in the United States commercially insured population. Neurology. 2016;**86**:1014-1021

[5] Rosati G. The prevalence of multiple sclerosis in the world: An update. Neurological Sciences. 2001;**22**:117-139

[6] Wallin MT, Culpepper WJ, Coffman P, et al. The gulf war era multiple sclerosis cohort: Age and incidence rates by race, sex and service. Brain. 2012;**135**:1778-1785

[7] Langer-Gould A, Brara SM, Beaber BE, et al. Incidence of multiple sclerosis in multiple racial and ethnic groups. Neurology. 2013;**80**:1734-1739

[8] Compston A. The genetic epidemiology of multiple sclerosis. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 1999;**354**:1623-1634

[9] Hansen T, Skytthe A, Stenager E, et al. Risk for multiple sclerosis in dizygotic and monozygotic twins. Multiple Sclerosis. 2005;**11**:500-503

[10] Wade BJ. Spatial analysis of global prevalence of multiple sclerosis suggests need for an updated prevalence scale. Multiple Sclerosis International. 2014;**2014**:124578

[11] Melcon MO, Correale J, Melcon CM. Is it time for a new global classification of multiple sclerosis? Journal of the Neurological Sciences. 2014;**344**:171-181

[12] Koch-Henriksen N, Sørensen PS. The changing demographic pattern of multiple sclerosis epidemiology. Lancet Neurology. 2010;**9**:520-532

[13] Berg-Hansen P, Celius EG. Socioeconomic factors and immigrant population studies of multiple sclerosis. Acta Neurologica Scandinavica. 2015;**132**:37-41

[14] Nasr Z, Majed M, Rostami A, et al. Prevalence of multiple sclerosis in Iranian emigrants: Review of the evidence. Neurological Sciences. 2016;**37**:1759-1763

[15] Ahlgren C, Lycke J, Odén A, et al. High risk of MS in Iranian immigrants in Gothenburg, Sweden. Multiple Sclerosis. 2010;**16**:1079-1082

[16] Berg-Hansen P, Moen SM, Sandvik L, et al. Prevalence of multiple sclerosis among immigrants in Norway. Multiple Sclerosis. 2015;**21**:695-702

[17] Milo R, Kahana E. Multiple sclerosis: Geoepidemiology, genetics and the environment. Autoimmunity Reviews. 2010;**9**:A387-A394

[18] McLeod JG, Hammond SR, Kurtzke JF. Migration and multiple sclerosis in immigrants to Australia from United Kingdom and Ireland: A reassessment. I. Risk of MS by age at immigration. Journal of Neurology. 2011;**258**:1140-1149

[19] Ascherio A, Munger KL. Environmental risk factors for multiple sclerosis. Part II: Noninfectious factors. Annals of Neurology. 2007;**61**:504-513

[20] Ascherio A, Munger KL, Lünemann JD. The initiation and prevention of multiple sclerosis. Nature Reviews. Neurology. 2012;**8**:602-612

[21] Correale J, Gaitán MI. Multiple sclerosis and environmental factors: The role of vitamin D, parasites, and Epstein-Barr virus infection. Acta Neurologica Scandinavica. 2015;**132**:46-55

[22] Reich DS, Lucchinetti CF, Calabresi PA. Multiple sclerosis. The New England Journal of Medicine. 2018;**378**:169-180

[23] Belbasis L, Bellou V, Evangelou E, et al. Environmental risk factors and multiple sclerosis: An umbrella review of systematic reviews and meta-analyses. Lancet Neurology. 2015;**14**:263-273

[24] Wallin MT, Heltberg A, Kurtzke JF. Multiple sclerosis in the Faroe Islands. 8. Notifiable diseases. Acta Neurologica Scandinavica. 2010;**122**:102-109

[25] Hughes A-M, Lucas RM, McMichael AJ, et al. Early-life hygiene-related factors affect risk of central nervous system demyelination and asthma differentially. Clinical and Experimental Immunology. 2013;**172**:466-474

[26] Gustavsen MW, Page CM, Moen SM, et al. Environmental exposures and the risk of multiple sclerosis investigated in a Norwegian case-control study. BMC Neurology. 2014;**14**:196

[27] Pedrini MJF, Seewann A, Bennett KA, et al. Helicobacter pylori infection as a protective factor against multiple sclerosis risk in females. Journal of Neurology, Neurosurgery, and Psychiatry. 2015;**86**:603-607

[28] Eskandarieh S, Heydarpour P, Minagar A, et al. Multiple sclerosis epidemiology in East Asia, South East Asia and South Asia: A systematic review. Neuroepidemiology. 2016;**46**:209-221

[29] Wendel-Haga M, Celius EG. Is the hygiene hypothesis relevant for the risk of multiple sclerosis? Acta Neurologica Scandinavica. 2017;**136**(Suppl 201):26-30

[30] Libbey JE, Cusick MF, Fujinami RS. Role of pathogens in multiple sclerosis. International Reviews of Immunology. 2014;**33**:266-283

[31] Lim Y, Romano N, Colin N, et al. Intestinal parasitic infections amongst orang Asli (indigenous) in Malaysia: Has socioeconomic development alleviated the problem? Tropical Biomedicine. 2009;**26**:110-122

[32] Ascherio A, Munger KL. 99th Dahlem conference on infection, inflammation and chronic inflammatory disorders: Epstein-Barr virus and multiple sclerosis: Epidemiological evidence. Clinical and Experimental Immunology. 2010;**160**:120-124

[33] Young LS, Yap LF, Murray PG. Epstein-Barr virus: More than 50 years old and still providing surprises. Nature Reviews. Cancer. 2016;**16**:789-802

[34] Dunmire SK, Verghese PS, Balfour HH. Primary Epstein-Barr virus infection. Journal of Clinical Virology. 2018;**102**:84-92

[35] Niedobitek G, Meru N, Delecluse HJ. Epstein-Barr virus infection and human malignancies. International Journal of Experimental Pathology. 2001;**82**:149-170

[36] Khan G, Hashim MJ. Global burden of deaths from Epstein-Barr virus attributable malignancies 1990-2010. Infectious Agents and Cancer. 2014;**9**:38

[37] Young LS, Rickinson AB. Epstein-Barr virus: 40 years on. Nature Reviews. Cancer. 2004;**4**:757-768

[38] Thorley-Lawson DA, Miyashita EM, Khan G. Epstein-Barr virus and the

**111**

*Epstein-Barr Virus in Multiple Sclerosis DOI: http://dx.doi.org/10.5772/intechopen.85222*

B cell: That's all it takes. Trends in Microbiology. 1996;**4**:204-208

[48] Sumaya CV, Myers LW, Ellison GW, et al. Increased prevalence and titer of Epstein-Barr virus antibodies in patients with multiple sclerosis. Annals of Neurology. 1985;**17**:371-377

[49] Pohl D, Krone B, Rostasy K, et al. High seroprevalence of Epstein-Barr virus in children with multiple sclerosis.

[50] Banwell B, Krupp L, Kennedy J, et al. Clinical features and viral serologies in children with

multiple sclerosis: A multinational observational study. Lancet Neurology.

[51] Alotaibi S, Kennedy J, Tellier R, et al. Epstein-Barr virus in pediatric multiple sclerosis. JAMA. 2004;**291**:1875-1879

[52] Waubant E, Mowry EM, Krupp L, et al. Common viruses associated with lower pediatric multiple sclerosis risk.

Neurology. 2011;**76**:1989-1995

[53] Ascherio A, Munch M. Epstein-Barr virus and multiple sclerosis. Epidemiology. 2000;**11**:220-224

[54] Levin LI, Munger KL, O'Reilly EJ, et al. Primary infection with the Epstein-Barr virus and risk of multiple

sclerosis. Annals of Neurology.

[56] Sawyer RN, Evans AS, Niederman JC, et al. Prospective studies of a group of Yale University freshmen. I. Occurrence of infectious mononucleosis. The Journal of Infectious Diseases. 1971;**123**:263-270

[57] Macsween KF, Higgins CD, McAulay KA, et al. Infectious

mononucleosis in university students in the United Kingdom: Evaluation of the clinical features and consequences of the disease. Clinical Infectious Diseases.

[55] Warner HB, Carp RI. Multiple sclerosis and Epstein-Barr virus. Lancet.

2010;**67**:824-830

2010;**50**:699-706

1981;**2**:1290

2007;**6**:773-781

Neurology. 2006;**67**:2063-2065

[39] Babcock GJ, Decker LL, Volk M, et al. EBV persistence in memory B cells in vivo. Immunity. 1998;**9**:395-404

[40] Khan G, Miyashita EM, Yang B, et al. Is EBV persistence in vivo a model for B cell homeostasis? Immunity.

[41] Brink AA, Dukers DF, van den Brule AJ, et al. Presence of Epstein-Barr virus latency type III at the single cell level in post-transplantation

Pathology. 1997;**50**:911-918

[43] Thorley-Lawson DA. EBV persistence–Introducing the virus. Current Topics in Microbiology and Immunology. 2015;**390**:151-209

[44] Skalsky RL, Cullen BR. EBV noncoding RNAs. Current Topics in Microbiology and Immunology.

[45] Kaul V, Weinberg KI, Boyd SD, et al. Dynamics of viral and host immune cell microRNA expression during acute infectious mononucleosis. Frontiers in

[47] Sumaya CV, Myers LW, Ellison GW.

Epstein-Barr virus antibodies in multiple sclerosis. Archives of Neurology. 1980;**37**:94-96

2015;**391**:181-217

Microbiology. 2017;**8**:2666

[46] Münz C. Epstein Barr virus–A tumor virus that needs cytotoxic lymphocytes to persist asymptomatically. Current Opinion in

Virology. 2016;**20**:34-39

lymphoproliferative disorders and AIDS related lymphomas. Journal of Clinical

primary infection and in the carrier state. Journal of Virology. 1994;**68**:7374-7385

[42] Tierney RJ, Steven N, Young LS, et al. Epstein-Barr virus latency in blood mononuclear cells: Analysis of viral gene transcription during

1996;**5**:173-179

*Epstein-Barr Virus in Multiple Sclerosis DOI: http://dx.doi.org/10.5772/intechopen.85222*

B cell: That's all it takes. Trends in Microbiology. 1996;**4**:204-208

*Multiple Sclerosis*

prevention of multiple sclerosis. Nature Reviews. Neurology. 2012;**8**:602-612

[29] Wendel-Haga M, Celius EG. Is the hygiene hypothesis relevant for the risk of multiple sclerosis? Acta Neurologica Scandinavica. 2017;**136**(Suppl 201):26-30

[30] Libbey JE, Cusick MF, Fujinami RS. Role of pathogens in multiple sclerosis. International Reviews of Immunology.

[31] Lim Y, Romano N, Colin N, et al. Intestinal parasitic infections amongst orang Asli (indigenous) in Malaysia: Has socioeconomic development alleviated the problem? Tropical Biomedicine. 2009;**26**:110-122

[32] Ascherio A, Munger KL. 99th Dahlem conference on infection,

disorders: Epstein-Barr virus and multiple sclerosis: Epidemiological evidence. Clinical and Experimental Immunology. 2010;**160**:120-124

[33] Young LS, Yap LF, Murray PG. Epstein-Barr virus: More than 50 years old and still providing surprises. Nature Reviews. Cancer. 2016;**16**:789-802

[34] Dunmire SK, Verghese PS,

[35] Niedobitek G, Meru N, Delecluse HJ. Epstein-Barr virus infection and human malignancies. International Journal of Experimental

Pathology. 2001;**82**:149-170

[36] Khan G, Hashim MJ. Global burden of deaths from Epstein-Barr virus attributable malignancies 1990-2010. Infectious Agents and

[37] Young LS, Rickinson AB. Epstein-Barr virus: 40 years on. Nature Reviews.

[38] Thorley-Lawson DA, Miyashita EM, Khan G. Epstein-Barr virus and the

2018;**102**:84-92

Cancer. 2014;**9**:38

Cancer. 2004;**4**:757-768

Balfour HH. Primary Epstein-Barr virus infection. Journal of Clinical Virology.

inflammation and chronic inflammatory

2014;**33**:266-283

[21] Correale J, Gaitán MI. Multiple sclerosis and environmental factors: The role of vitamin D, parasites, and Epstein-Barr virus infection. Acta Neurologica

Scandinavica. 2015;**132**:46-55

[22] Reich DS, Lucchinetti CF, Calabresi PA. Multiple sclerosis. The New England Journal of Medicine.

[23] Belbasis L, Bellou V, Evangelou E, et al. Environmental risk factors and multiple sclerosis: An umbrella review of systematic reviews and meta-analyses. Lancet Neurology.

[24] Wallin MT, Heltberg A, Kurtzke JF. Multiple sclerosis in the Faroe Islands. 8. Notifiable diseases. Acta Neurologica

[26] Gustavsen MW, Page CM, Moen SM, et al. Environmental exposures and the risk of multiple sclerosis investigated in a Norwegian case-control study. BMC

Scandinavica. 2010;**122**:102-109

[25] Hughes A-M, Lucas RM, McMichael AJ, et al. Early-life hygiene-related factors affect risk of central nervous system demyelination and asthma differentially. Clinical and Experimental Immunology.

2018;**378**:169-180

2015;**14**:263-273

2013;**172**:466-474

Neurology. 2014;**14**:196

[27] Pedrini MJF, Seewann A,

Bennett KA, et al. Helicobacter pylori infection as a protective factor against multiple sclerosis risk in females. Journal of Neurology, Neurosurgery, and Psychiatry. 2015;**86**:603-607

[28] Eskandarieh S, Heydarpour P, Minagar A, et al. Multiple sclerosis epidemiology in East Asia, South East Asia and South Asia: A systematic review. Neuroepidemiology.

**110**

2016;**46**:209-221

[39] Babcock GJ, Decker LL, Volk M, et al. EBV persistence in memory B cells in vivo. Immunity. 1998;**9**:395-404

[40] Khan G, Miyashita EM, Yang B, et al. Is EBV persistence in vivo a model for B cell homeostasis? Immunity. 1996;**5**:173-179

[41] Brink AA, Dukers DF, van den Brule AJ, et al. Presence of Epstein-Barr virus latency type III at the single cell level in post-transplantation lymphoproliferative disorders and AIDS related lymphomas. Journal of Clinical Pathology. 1997;**50**:911-918

[42] Tierney RJ, Steven N, Young LS, et al. Epstein-Barr virus latency in blood mononuclear cells: Analysis of viral gene transcription during primary infection and in the carrier state. Journal of Virology. 1994;**68**:7374-7385

[43] Thorley-Lawson DA. EBV persistence–Introducing the virus. Current Topics in Microbiology and Immunology. 2015;**390**:151-209

[44] Skalsky RL, Cullen BR. EBV noncoding RNAs. Current Topics in Microbiology and Immunology. 2015;**391**:181-217

[45] Kaul V, Weinberg KI, Boyd SD, et al. Dynamics of viral and host immune cell microRNA expression during acute infectious mononucleosis. Frontiers in Microbiology. 2017;**8**:2666

[46] Münz C. Epstein Barr virus–A tumor virus that needs cytotoxic lymphocytes to persist asymptomatically. Current Opinion in Virology. 2016;**20**:34-39

[47] Sumaya CV, Myers LW, Ellison GW. Epstein-Barr virus antibodies in multiple sclerosis. Archives of Neurology. 1980;**37**:94-96

[48] Sumaya CV, Myers LW, Ellison GW, et al. Increased prevalence and titer of Epstein-Barr virus antibodies in patients with multiple sclerosis. Annals of Neurology. 1985;**17**:371-377

[49] Pohl D, Krone B, Rostasy K, et al. High seroprevalence of Epstein-Barr virus in children with multiple sclerosis. Neurology. 2006;**67**:2063-2065

[50] Banwell B, Krupp L, Kennedy J, et al. Clinical features and viral serologies in children with multiple sclerosis: A multinational observational study. Lancet Neurology. 2007;**6**:773-781

[51] Alotaibi S, Kennedy J, Tellier R, et al. Epstein-Barr virus in pediatric multiple sclerosis. JAMA. 2004;**291**:1875-1879

[52] Waubant E, Mowry EM, Krupp L, et al. Common viruses associated with lower pediatric multiple sclerosis risk. Neurology. 2011;**76**:1989-1995

[53] Ascherio A, Munch M. Epstein-Barr virus and multiple sclerosis. Epidemiology. 2000;**11**:220-224

[54] Levin LI, Munger KL, O'Reilly EJ, et al. Primary infection with the Epstein-Barr virus and risk of multiple sclerosis. Annals of Neurology. 2010;**67**:824-830

[55] Warner HB, Carp RI. Multiple sclerosis and Epstein-Barr virus. Lancet. 1981;**2**:1290

[56] Sawyer RN, Evans AS, Niederman JC, et al. Prospective studies of a group of Yale University freshmen. I. Occurrence of infectious mononucleosis. The Journal of Infectious Diseases. 1971;**123**:263-270

[57] Macsween KF, Higgins CD, McAulay KA, et al. Infectious mononucleosis in university students in the United Kingdom: Evaluation of the clinical features and consequences of the disease. Clinical Infectious Diseases. 2010;**50**:699-706

[58] Lucas RM, Ponsonby A-L, Dear K, et al. Current and past Epstein-Barr virus infection in risk of initial CNS demyelination. Neurology. 2011;**77**:371-379

[59] Thacker EL, Mirzaei F, Ascherio A. Infectious mononucleosis and risk for multiple sclerosis: A meta-analysis. Annals of Neurology. 2006;**59**:499-503

[60] Nielsen TR, Rostgaard K, Nielsen NM, et al. Multiple sclerosis after infectious mononucleosis. Archives of Neurology. 2007;**64**:72-75

[61] Haahr S, Koch-Henriksen N, Møller-Larsen A, et al. Increased risk of multiple sclerosis after late Epstein-Barr virus infection: A historical prospective study. Multiple Sclerosis. 1995;**1**:73-77

[62] Levin LI, Munger KL, Rubertone MV, et al. Temporal relationship between elevation of Epstein-Barr virus antibody titers and initial onset of neurological symptoms in multiple sclerosis. JAMA. 2005;**293**:2496-2500

[63] Sundström P, Juto P, Wadell G, et al. An altered immune response to Epstein-Barr virus in multiple sclerosis: A prospective study. Neurology. 2004;**62**:2277-2282

[64] DeLorenze GN, Munger KL, Lennette ET, et al. Epstein-Barr virus and multiple sclerosis: Evidence of association from a prospective study with long-term follow-up. Archives of Neurology. 2006;**63**:839-844

[65] Comabella M, Montalban X, Horga A, et al. Antiviral immune response in patients with multiple sclerosis and healthy siblings. Multiple Sclerosis. 2010;**16**:355-358

[66] Lünemann JD, Tintoré M, Messmer B, et al. Elevated Epstein-Barr virus-encoded nuclear antigen-1 immune responses predict conversion to multiple sclerosis. Annals of Neurology. 2010;**67**:159-169

[67] Schlemm L, Giess RM, Rasche L, et al. Fine specificity of the antibody response to Epstein-Barr nuclear antigen-2 and other Epstein-Barr virus proteins in patients with clinically isolated syndrome: A peptide microarray-based case-control study. Journal of Neuroimmunology. 2016;**297**:56-62

[68] Ascherio A, Munger KL, Lennette ET, et al. Epstein-Barr virus antibodies and risk of multiple sclerosis: A prospective study. JAMA. 2001;**286**:3083-3088

[69] Sundqvist E, Sundström P, Lindén M, et al. Epstein-Barr virus and multiple sclerosis: Interaction with HLA. Genes and Immunity. 2012;**13**:14-20

[70] Rubicz R, Yolken R, Drigalenko E, et al. A genome-wide integrative genomic study localizes genetic factors influencing antibodies against Epstein-Barr virus nuclear antigen 1 (EBNA-1). PLoS Genetics. 2013;**9**:e1003147

[71] Farrell RA, Antony D, Wall GR, et al. Humoral immune response to EBV in multiple sclerosis is associated with disease activity on MRI. Neurology. 2009;**73**:32-38

[72] Almohmeed YH, Avenell A, Aucott L, et al. Systematic review and meta-analysis of the seroepidemiological association between Epstein Barr virus and multiple sclerosis. PLoS One. 2013;**8**:e61110

[73] Zivadinov R, Cerza N, Hagemeier J, et al. Humoral response to EBV is associated with cortical atrophy and lesion burden in patients with MS. Neurology Neuroimmunology & Neuroinflammation. 2016;**3**:e190

[74] Wandinger K, Jabs W, Siekhaus A, et al. Association between clinical

**113**

*Epstein-Barr Virus in Multiple Sclerosis DOI: http://dx.doi.org/10.5772/intechopen.85222*

disease activity and Epstein-Barr virus reactivation in MS. Neurology. Epstein-Barr virus lytic antigens in the active phase of multiple sclerosis. PLoS

Pathogens. 2013;**9**:e1003220

[83] Pender MP, Csurhes PA, Burrows JM, et al. Defective T-cell control of Epstein-Barr virus infection in multiple sclerosis. Clinical & Translational Immunology. 2017;**6**:e126

[84] Cencioni MT, Magliozzi R,

2017;**152**:660-676

2006;**443**:350-354

Nicholas R, et al. Programmed death 1 is highly expressed on CD8+ CD57+ T cells in patients with stable multiple sclerosis and inhibits their cytotoxic response to Epstein-Barr virus. Immunology.

[85] Day CL, Kaufmann DE, Kiepiela P, et al. PD-1 expression on HIV-specific T cells is associated with T-cell exhaustion and disease progression. Nature.

[86] Barber DL, Wherry EJ, Masopust D, et al. Restoring function in exhausted CD8 T cells during chronic viral infection. Nature. 2006;**439**:682-687

[87] Wherry EJ. T cell exhaustion. Nature Immunology. 2011;**12**:492-499

[88] Wagner H-J, Munger KL, Ascherio A. Plasma viral load of Epstein-Barr virus and risk of multiple

sclerosis. European Journal of Neurology. 2004;**11**:833-834

[90] Lindsey JW, Hatfield LM,

2009;**15**:153-158

Crawford MP, et al. Quantitative PCR for Epstein-Barr virus DNA and RNA in multiple sclerosis. Multiple Sclerosis.

[91] Holden DW, Gold J, Hawkes CH, et al. Epstein Barr virus shedding in multiple sclerosis: Similar frequencies of EBV in saliva across separate patient

[89] Agostini S, Mancuso R, Guerini FR, et al. HLA alleles modulate EBV viral load in multiple sclerosis. Journal of Translational Medicine. 2018;**16**:80

[75] Buljevac D, van Doornum GJJ, Flach HZ, et al. Epstein-Barr virus and disease activity in multiple sclerosis. Journal of Neurology, Neurosurgery, and Psychiatry. 2005;**76**:1377-1381

[76] Gieß RM, Pfuhl C, Behrens JR, et al. Epstein-Barr virus antibodies in serum and DNA load in saliva are not associated with radiological or clinical disease activity in patients with early multiple sclerosis. PLoS One.

[77] Kakalacheva K, Regenass S, Wiesmayr S, et al. Infectious mononucleosis triggers generation of IgG auto-antibodies against native myelin oligodendrocyte glycoprotein. Viruses. 2016;**8**. DOI: 10.3390/v8020051

[78] Wergeland S, Myhr K-M, Løken-Amsrud KI, et al. Vitamin D, HLA-DRB1 and Epstein-Barr virus antibody levels in a prospective cohort of multiple sclerosis patients. European Journal of

Neurology. 2016;**23**:1064-1070

Sclerosis. 2018;**24**:1280-1287

Lancet. 1979;**2**:175-176

2012;**188**:4671-4680

[79] Rolf L, Muris A-H, Mathias A, et al. Exploring the effect of vitamin D3 supplementation on the anti-EBV antibody response in relapsingremitting multiple sclerosis. Multiple

[80] Fraser KB, Haire M, Millar JH, et al. Increased tendency to spontaneous in-vitro lymphocyte transformation in clinically active multiple sclerosis.

[81] Jilek S, Schluep M, Harari A, et al. HLA-B7-restricted EBV-specific CD8+ T cells are dysregulated in multiple sclerosis. Journal of Immunology.

[82] Angelini DF, Serafini B, Piras E, et al. Increased CD8+ T cell response to

2000;**55**:178-184

2017;**12**:e0175279

## *Epstein-Barr Virus in Multiple Sclerosis DOI: http://dx.doi.org/10.5772/intechopen.85222*

disease activity and Epstein-Barr virus reactivation in MS. Neurology. 2000;**55**:178-184

*Multiple Sclerosis*

2011;**77**:371-379

[58] Lucas RM, Ponsonby A-L, Dear K, et al. Current and past Epstein-Barr virus infection in risk of initial CNS demyelination. Neurology.

multiple sclerosis. Annals of Neurology.

[67] Schlemm L, Giess RM, Rasche L, et al. Fine specificity of the antibody response to Epstein-Barr nuclear antigen-2 and other Epstein-Barr virus proteins in patients with clinically isolated syndrome: A

peptide microarray-based case-control study. Journal of Neuroimmunology.

[69] Sundqvist E, Sundström P, Lindén M, et al. Epstein-Barr virus and multiple sclerosis: Interaction with HLA. Genes

[70] Rubicz R, Yolken R, Drigalenko E, et al. A genome-wide integrative genomic study localizes genetic factors influencing antibodies against Epstein-Barr virus nuclear antigen 1 (EBNA-1). PLoS Genetics. 2013;**9**:e1003147

[71] Farrell RA, Antony D, Wall GR, et al. Humoral immune response to EBV in multiple sclerosis is associated with disease activity on MRI. Neurology.

[72] Almohmeed YH, Avenell A, Aucott L, et al. Systematic review and meta-analysis of the seroepidemiological association between Epstein Barr virus and multiple sclerosis. PLoS One. 2013;**8**:e61110

[73] Zivadinov R, Cerza N, Hagemeier J, et al. Humoral response to EBV is associated with cortical atrophy and lesion burden in patients with MS. Neurology Neuroimmunology & Neuroinflammation. 2016;**3**:e190

[74] Wandinger K, Jabs W, Siekhaus A, et al. Association between clinical

2009;**73**:32-38

[68] Ascherio A, Munger KL, Lennette ET, et al. Epstein-Barr virus antibodies and risk of multiple sclerosis: A prospective study. JAMA.

and Immunity. 2012;**13**:14-20

2010;**67**:159-169

2016;**297**:56-62

2001;**286**:3083-3088

[59] Thacker EL, Mirzaei F, Ascherio A. Infectious mononucleosis and risk for multiple sclerosis: A meta-analysis. Annals of Neurology. 2006;**59**:499-503

[60] Nielsen TR, Rostgaard K, Nielsen NM, et al. Multiple sclerosis after infectious mononucleosis. Archives of Neurology. 2007;**64**:72-75

[61] Haahr S, Koch-Henriksen N, Møller-Larsen A, et al. Increased risk of multiple sclerosis after late Epstein-Barr virus infection: A historical prospective study. Multiple Sclerosis. 1995;**1**:73-77

[62] Levin LI, Munger KL, Rubertone MV, et al. Temporal relationship between elevation of Epstein-Barr virus antibody titers and initial onset of neurological symptoms in multiple sclerosis. JAMA.

2005;**293**:2496-2500

2004;**62**:2277-2282

[63] Sundström P, Juto P, Wadell G, et al. An altered immune response to Epstein-Barr virus in multiple sclerosis:

A prospective study. Neurology.

[64] DeLorenze GN, Munger KL, Lennette ET, et al. Epstein-Barr virus and multiple sclerosis: Evidence of association from a prospective study with long-term follow-up. Archives of

Neurology. 2006;**63**:839-844

Sclerosis. 2010;**16**:355-358

[66] Lünemann JD, Tintoré M, Messmer B, et al. Elevated Epstein-Barr virus-encoded nuclear antigen-1 immune responses predict conversion to

[65] Comabella M, Montalban X, Horga A, et al. Antiviral immune response in patients with multiple sclerosis and healthy siblings. Multiple

**112**

[75] Buljevac D, van Doornum GJJ, Flach HZ, et al. Epstein-Barr virus and disease activity in multiple sclerosis. Journal of Neurology, Neurosurgery, and Psychiatry. 2005;**76**:1377-1381

[76] Gieß RM, Pfuhl C, Behrens JR, et al. Epstein-Barr virus antibodies in serum and DNA load in saliva are not associated with radiological or clinical disease activity in patients with early multiple sclerosis. PLoS One. 2017;**12**:e0175279

[77] Kakalacheva K, Regenass S, Wiesmayr S, et al. Infectious mononucleosis triggers generation of IgG auto-antibodies against native myelin oligodendrocyte glycoprotein. Viruses. 2016;**8**. DOI: 10.3390/v8020051

[78] Wergeland S, Myhr K-M, Løken-Amsrud KI, et al. Vitamin D, HLA-DRB1 and Epstein-Barr virus antibody levels in a prospective cohort of multiple sclerosis patients. European Journal of Neurology. 2016;**23**:1064-1070

[79] Rolf L, Muris A-H, Mathias A, et al. Exploring the effect of vitamin D3 supplementation on the anti-EBV antibody response in relapsingremitting multiple sclerosis. Multiple Sclerosis. 2018;**24**:1280-1287

[80] Fraser KB, Haire M, Millar JH, et al. Increased tendency to spontaneous in-vitro lymphocyte transformation in clinically active multiple sclerosis. Lancet. 1979;**2**:175-176

[81] Jilek S, Schluep M, Harari A, et al. HLA-B7-restricted EBV-specific CD8+ T cells are dysregulated in multiple sclerosis. Journal of Immunology. 2012;**188**:4671-4680

[82] Angelini DF, Serafini B, Piras E, et al. Increased CD8+ T cell response to Epstein-Barr virus lytic antigens in the active phase of multiple sclerosis. PLoS Pathogens. 2013;**9**:e1003220

[83] Pender MP, Csurhes PA, Burrows JM, et al. Defective T-cell control of Epstein-Barr virus infection in multiple sclerosis. Clinical & Translational Immunology. 2017;**6**:e126

[84] Cencioni MT, Magliozzi R, Nicholas R, et al. Programmed death 1 is highly expressed on CD8+ CD57+ T cells in patients with stable multiple sclerosis and inhibits their cytotoxic response to Epstein-Barr virus. Immunology. 2017;**152**:660-676

[85] Day CL, Kaufmann DE, Kiepiela P, et al. PD-1 expression on HIV-specific T cells is associated with T-cell exhaustion and disease progression. Nature. 2006;**443**:350-354

[86] Barber DL, Wherry EJ, Masopust D, et al. Restoring function in exhausted CD8 T cells during chronic viral infection. Nature. 2006;**439**:682-687

[87] Wherry EJ. T cell exhaustion. Nature Immunology. 2011;**12**:492-499

[88] Wagner H-J, Munger KL, Ascherio A. Plasma viral load of Epstein-Barr virus and risk of multiple sclerosis. European Journal of Neurology. 2004;**11**:833-834

[89] Agostini S, Mancuso R, Guerini FR, et al. HLA alleles modulate EBV viral load in multiple sclerosis. Journal of Translational Medicine. 2018;**16**:80

[90] Lindsey JW, Hatfield LM, Crawford MP, et al. Quantitative PCR for Epstein-Barr virus DNA and RNA in multiple sclerosis. Multiple Sclerosis. 2009;**15**:153-158

[91] Holden DW, Gold J, Hawkes CH, et al. Epstein Barr virus shedding in multiple sclerosis: Similar frequencies of EBV in saliva across separate patient cohorts. Multiple Sclerosis and Related Disorders. 2018;**25**:197-199

[92] Marrie RA, Elliott L, Marriott J, et al. Dramatically changing rates and reasons for hospitalization in multiple sclerosis. Neurology. 2014;**83**:929-937

[93] Glenn JD, Smith MD, Xue P, et al. CNS-targeted autoimmunity leads to increased influenza mortality in mice. Journal of Experimental Medicine. 2017;**214**:297-307

[94] Tørring C, Andreasen C, Gehr N, et al. Higher incidence of Epstein-Barr virus-induced lymphocyte transformation in multiple sclerosis. Acta Neurologica Scandinavica. 2014;**130**:90-96

[95] Lossius A, Johansen JN, Vartdal F, et al. High-throughput sequencing of TCR repertoires in multiple sclerosis reveals intrathecal enrichment of EBV-reactive CD8+ T cells. European Journal of Immunology. 2014;**44**:3439-3452

[96] van Nierop GP, Mautner J, Mitterreiter JG, et al. Intrathecal CD8 T-cells of multiple sclerosis patients recognize lytic Epstein-Barr virus proteins. Multiple Sclerosis. 2016;**22**:279-291

[97] van Nierop GP, Janssen M, Mitterreiter JG, et al. Intrathecal CD4(+) and CD8(+) T-cell responses to endogenously synthesized candidate disease-associated human autoantigens in multiple sclerosis patients. European Journal of Immunology. 2016;**46**:347-353

[98] Planas R, Santos R, Tomas-Ojer P, et al. GDP-l-fucose synthase is a CD4+ T cell–specific autoantigen in DRB3\*02:02 patients with multiple sclerosis. Science Translational Medicine. 2018;**10**:eaat4301

[99] Wekerle H, Hohlfeld R. Molecular mimicry in multiple sclerosis. The

New England Journal of Medicine. 2003;**349**:185-186

[100] Wherry EJ, Kurachi M. Molecular and cellular insights into T cell exhaustion. Nature Reviews. Immunology. 2015;**15**:486-499

[101] Geginat J, Paroni M, Pagani M, et al. The enigmatic role of viruses in multiple sclerosis: Molecular mimicry or disturbed immune surveillance? Trends in Immunology. 2017;**38**:498-512

[102] Lünemann JD, Jelcić I, Roberts S, et al. EBNA1-specific T cells from patients with multiple sclerosis cross react with myelin antigens and co-produce IFN-gamma and IL-2. The Journal of Experimental Medicine. 2008;**205**:1763-1773

[103] Cepok S, Zhou D, Srivastava R, et al. Identification of Epstein-Barr virus proteins as putative targets of the immune response in multiple sclerosis. The Journal of Clinical Investigation. 2005;**115**:1352-1360

[104] Lünemann JD, Edwards N, Muraro PA, et al. Increased frequency and broadened specificity of latent EBV nuclear antigen-1-specific T cells in multiple sclerosis. Brain. 2006;**129**:1493-1506

[105] Hilton DA, Love S, Fletcher A, et al. Absence of Epstein-Barr virus RNA in multiple sclerosis as assessed by in situ hybridisation. Journal of Neurology, Neurosurgery, and Psychiatry. 1994;**57**:975-976

[106] Opsahl ML, Kennedy PGE. An attempt to investigate the presence of Epstein Barr virus in multiple sclerosis and normal control brain tissue. Journal of Neurology. 2007;**254**:425-430

**115**

*Epstein-Barr Virus in Multiple Sclerosis DOI: http://dx.doi.org/10.5772/intechopen.85222*

Journal of Experimental Medicine.

and may engage more than just B cells.

PLoS One. 2018;**13**:e0192109

[116] Naegelin Y, Naegelin P, von Felten S, et al. Association of rituximab treatment with disability progression among patients with secondary progressive multiple sclerosis. JAMA Neurology. 2019. DOI:

10.1001/jamaneurol.2018.4239

2017;**16**:41-50

[117] Baker D, Marta M, Pryce G, et al. Memory B cells are major targets for effective immunotherapy in relapsing multiple sclerosis. eBioMedicine.

[118] Jelcic I, Al Nimer F, Wang J, et al. Memory B cells activate brain-homing, autoreactive CD4+ T cells in multiple sclerosis. Cell. 2018;**175**:85-100. e23

[119] Michel L, Touil H, Pikor NB, et al. B Cells in the multiple sclerosis central nervous system: Trafficking and contribution to CNScompartmentalized Inflammation. Frontiers in Immunology. 2015;**6**. DOI:

10.3389/fimmu.2015.00636

[120] Blauth K, Owens GP, Bennett JL. The ins and outs of B cells in multiple sclerosis. Frontiers in Immunology. 2015;**6**. DOI: 10.3389/

Virology. 2005;**79**:1296-1307

[121] Laichalk LL, Thorley-Lawson DA. Terminal differentiation into plasma cells initiates the replicative cycle of Epstein-Barr virus In vivo. Journal of

[122] Moreno MA, Or-Geva N, Aftab BT, et al. Molecular signature of Epstein-Barr virus infection in MS brain lesions. Neurology–Neuroimmunology Neuroinflammation. 2018;**5**:e466

[123] Gasque P, Chan P, Mauger C, et al. Identification and characterization of complement C3 receptors on human astrocytes. The Journal of Immunology.

fimmu.2015.00565

1996;**156**:2247-2255

Vossenkamper A, et al. Association of innate immune activation with latent Epstein-Barr virus in active MS lesions.

Rosicarelli B, et al. B-cell enrichment and Epstein-Barr virus infection in inflammatory cortical lesions in secondary progressive multiple sclerosis. Journal of Neuropathology and Experimental Neurology.

2007;**204**:2899-2912

[108] Tzartos JS, Khan G,

Neurology. 2012;**78**:15-23

2013;**72**:29-41

2009;**132**:3318-3328

[109] Magliozzi R, Serafini B,

[110] Willis SN, Stadelmann C, Rodig SJ, et al. Epstein-Barr virus infection is not a characteristic feature of multiple sclerosis brain. Brain.

[111] Peferoen LAN, Lamers F,

sclerosis. Brain. 2010;**133**:e137

[112] Sargsyan SA, Shearer AJ,

[113] Lassmann H, Niedobitek G, Aloisi F, et al. Epstein-Barr virus in the multiple sclerosis brain: A controversial issue–Report on a focused workshop held in the Centre for Brain Research of the Medical University of Vienna, Austria. Brain. 2011;**134**:2772-2786

[114] Aloisi F, Serafini B, Magliozzi R, et al. Detection of Epstein-Barr virus and B-cell follicles in the multiple sclerosis brain: What you find depends on how and where you look. Brain. 2010;**133**:e157

[115] Hassani A, Corboy JR, Al-Salam S, et al. Epstein-Barr virus is present in the brain of most cases of multiple sclerosis

Lodder LNR, et al. Epstein Barr virus is not a characteristic feature in the central nervous system in established multiple

Ritchie AM, et al. Absence of Epstein-Barr virus in the brain and CSF of patients with multiple sclerosis. Neurology. 2010;**74**:1127-1135

[107] Serafini B, Rosicarelli B, Franciotta D, et al. Dysregulated Epstein-Barr virus infection in the multiple sclerosis brain. The

*Epstein-Barr Virus in Multiple Sclerosis DOI: http://dx.doi.org/10.5772/intechopen.85222*

Journal of Experimental Medicine. 2007;**204**:2899-2912

*Multiple Sclerosis*

2017;**214**:297-307

2014;**130**:90-96

2014;**44**:3439-3452

2016;**22**:279-291

[96] van Nierop GP, Mautner J, Mitterreiter JG, et al. Intrathecal CD8 T-cells of multiple sclerosis patients recognize lytic Epstein-Barr virus proteins. Multiple Sclerosis.

[97] van Nierop GP, Janssen M, Mitterreiter JG, et al. Intrathecal CD4(+) and CD8(+) T-cell responses to endogenously synthesized candidate disease-associated human autoantigens in multiple sclerosis patients. European Journal of Immunology. 2016;**46**:347-353

[98] Planas R, Santos R, Tomas-Ojer P, et al. GDP-l-fucose synthase is a CD4+ T cell–specific autoantigen in DRB3\*02:02

[99] Wekerle H, Hohlfeld R. Molecular mimicry in multiple sclerosis. The

patients with multiple sclerosis. Science Translational Medicine.

2018;**10**:eaat4301

cohorts. Multiple Sclerosis and Related

New England Journal of Medicine.

and cellular insights into T cell exhaustion. Nature Reviews. Immunology. 2015;**15**:486-499

[100] Wherry EJ, Kurachi M. Molecular

[101] Geginat J, Paroni M, Pagani M, et al. The enigmatic role of viruses in multiple sclerosis: Molecular mimicry or disturbed immune surveillance? Trends

in Immunology. 2017;**38**:498-512

2008;**205**:1763-1773

2005;**115**:1352-1360

2006;**129**:1493-1506

[102] Lünemann JD, Jelcić I, Roberts S, et al. EBNA1-specific T cells from patients with multiple sclerosis cross react with myelin antigens and co-produce IFN-gamma and IL-2. The Journal of Experimental Medicine.

[103] Cepok S, Zhou D, Srivastava R, et al. Identification of Epstein-Barr virus proteins as putative targets of the immune response in multiple sclerosis. The Journal of Clinical Investigation.

[104] Lünemann JD, Edwards N, Muraro PA, et al. Increased frequency and broadened specificity of latent EBV nuclear antigen-1-specific T cells in multiple sclerosis. Brain.

[105] Hilton DA, Love S, Fletcher A, et al. Absence of Epstein-Barr virus RNA in multiple sclerosis as assessed by in situ hybridisation. Journal of Neurology, Neurosurgery, and Psychiatry. 1994;**57**:975-976

[106] Opsahl ML, Kennedy PGE. An attempt to investigate the presence of Epstein Barr virus in multiple sclerosis and normal control brain tissue. Journal

of Neurology. 2007;**254**:425-430

[107] Serafini B, Rosicarelli B, Franciotta D, et al. Dysregulated Epstein-Barr virus infection in the multiple sclerosis brain. The

2003;**349**:185-186

[92] Marrie RA, Elliott L, Marriott J, et al. Dramatically changing rates and reasons for hospitalization in multiple sclerosis. Neurology. 2014;**83**:929-937

[93] Glenn JD, Smith MD, Xue P, et al. CNS-targeted autoimmunity leads to increased influenza mortality in mice. Journal of Experimental Medicine.

[94] Tørring C, Andreasen C, Gehr N, et al. Higher incidence of Epstein-Barr virus-induced lymphocyte transformation in multiple sclerosis. Acta Neurologica Scandinavica.

[95] Lossius A, Johansen JN, Vartdal F, et al. High-throughput sequencing of TCR repertoires in multiple sclerosis reveals intrathecal enrichment of EBV-reactive CD8+ T cells. European Journal of Immunology.

Disorders. 2018;**25**:197-199

**114**

[108] Tzartos JS, Khan G, Vossenkamper A, et al. Association of innate immune activation with latent Epstein-Barr virus in active MS lesions. Neurology. 2012;**78**:15-23

[109] Magliozzi R, Serafini B, Rosicarelli B, et al. B-cell enrichment and Epstein-Barr virus infection in inflammatory cortical lesions in secondary progressive multiple sclerosis. Journal of Neuropathology and Experimental Neurology. 2013;**72**:29-41

[110] Willis SN, Stadelmann C, Rodig SJ, et al. Epstein-Barr virus infection is not a characteristic feature of multiple sclerosis brain. Brain. 2009;**132**:3318-3328

[111] Peferoen LAN, Lamers F, Lodder LNR, et al. Epstein Barr virus is not a characteristic feature in the central nervous system in established multiple sclerosis. Brain. 2010;**133**:e137

[112] Sargsyan SA, Shearer AJ, Ritchie AM, et al. Absence of Epstein-Barr virus in the brain and CSF of patients with multiple sclerosis. Neurology. 2010;**74**:1127-1135

[113] Lassmann H, Niedobitek G, Aloisi F, et al. Epstein-Barr virus in the multiple sclerosis brain: A controversial issue–Report on a focused workshop held in the Centre for Brain Research of the Medical University of Vienna, Austria. Brain. 2011;**134**:2772-2786

[114] Aloisi F, Serafini B, Magliozzi R, et al. Detection of Epstein-Barr virus and B-cell follicles in the multiple sclerosis brain: What you find depends on how and where you look. Brain. 2010;**133**:e157

[115] Hassani A, Corboy JR, Al-Salam S, et al. Epstein-Barr virus is present in the brain of most cases of multiple sclerosis

and may engage more than just B cells. PLoS One. 2018;**13**:e0192109

[116] Naegelin Y, Naegelin P, von Felten S, et al. Association of rituximab treatment with disability progression among patients with secondary progressive multiple sclerosis. JAMA Neurology. 2019. DOI: 10.1001/jamaneurol.2018.4239

[117] Baker D, Marta M, Pryce G, et al. Memory B cells are major targets for effective immunotherapy in relapsing multiple sclerosis. eBioMedicine. 2017;**16**:41-50

[118] Jelcic I, Al Nimer F, Wang J, et al. Memory B cells activate brain-homing, autoreactive CD4+ T cells in multiple sclerosis. Cell. 2018;**175**:85-100. e23

[119] Michel L, Touil H, Pikor NB, et al. B Cells in the multiple sclerosis central nervous system: Trafficking and contribution to CNScompartmentalized Inflammation. Frontiers in Immunology. 2015;**6**. DOI: 10.3389/fimmu.2015.00636

[120] Blauth K, Owens GP, Bennett JL. The ins and outs of B cells in multiple sclerosis. Frontiers in Immunology. 2015;**6**. DOI: 10.3389/ fimmu.2015.00565

[121] Laichalk LL, Thorley-Lawson DA. Terminal differentiation into plasma cells initiates the replicative cycle of Epstein-Barr virus In vivo. Journal of Virology. 2005;**79**:1296-1307

[122] Moreno MA, Or-Geva N, Aftab BT, et al. Molecular signature of Epstein-Barr virus infection in MS brain lesions. Neurology–Neuroimmunology Neuroinflammation. 2018;**5**:e466

[123] Gasque P, Chan P, Mauger C, et al. Identification and characterization of complement C3 receptors on human astrocytes. The Journal of Immunology. 1996;**156**:2247-2255

[124] Sofroniew MV, Vinters HV. Astrocytes: Biology and pathology. Acta Neuropathologica. 2010;**119**:7-35

[125] Liddelow SA, Barres BA. Reactive astrocytes: Production, function, and therapeutic potential. Immunity. 2017;**46**:957-967

[126] Liddelow SA, Guttenplan KA, Clarke LE, et al. Neurotoxic reactive astrocytes are induced by activated microglia. Nature. 2017;**541**:481-487

[127] Sankowski R, Mader S, Valdés-Ferrer SI. Systemic inflammation and the brain: Novel roles of genetic, molecular, and environmental cues as drivers of neurodegeneration. Frontiers in Cellular Neuroscience. 2015;**9**. DOI: 10.3389/fncel.2015.00028

[128] Aloisi F, Pujol-Borrell R. Lymphoid neogenesis in chronic inflammatory diseases. Nature Reviews. Immunology. 2006;**6**:205-217

[129] Pikor NB, Prat A, Bar-Or A, et al. Meningeal tertiary lymphoid tissues and multiple sclerosis: A gathering place for diverse types of immune cells during CNS autoimmunity. Frontiers in Immunology. 2016;**6**. DOI: 10.3389/ fimmu.2015.00657

[130] Corcione A, Casazza S, Ferretti E, et al. Recapitulation of B cell differentiation in the central nervous system of patients with multiple sclerosis. PNAS. 2004;**101**:11064-11069

[131] Ahmed W, Tariq S, Khan G. Tracking EBV-encoded RNAs (EBERs) from the nucleus to the excreted exosomes of B-lymphocytes. Scientific Reports. 2018;**8**:15438

[132] Moutsianas L, Jostins L, Beecham AH, et al. Class II HLA interactions modulate genetic risk for multiple sclerosis. Nature Genetics. 2015;**47**:1107-1113

[133] Hanisch U-K, Kettenmann H. Microglia: Active sensor and versatile effector cells in the normal and pathologic brain. Nature Neuroscience. 2007;**10**:1387-1394

[134] Voet S, Prinz M, van Loo G. Microglia in central nervous system inflammation and multiple sclerosis pathology. Trends in Molecular Medicine. 2018;**25**:112-123. DOI: 10.1016/j.molmed.2018.11.005

[135] Pender MP, Csurhes PA, Smith C, et al. Epstein-Barr virus-specific T cell therapy for progressive multiple sclerosis. JCI Insight. 2018;**3**. DOI: 10.1172/jci.insight.124714

[136] Cohen JI. Epstein-Barr virus vaccines. Clinical & Translational Immunology. 2015;**4**:e32

*Multiple Sclerosis*

2017;**46**:957-967

[124] Sofroniew MV, Vinters HV.

Neuropathologica. 2010;**119**:7-35

Astrocytes: Biology and pathology. Acta

[133] Hanisch U-K, Kettenmann H. Microglia: Active sensor and versatile effector cells in the normal and

[134] Voet S, Prinz M, van Loo G. Microglia in central nervous system inflammation and multiple sclerosis pathology. Trends in Molecular Medicine. 2018;**25**:112-123. DOI: 10.1016/j.molmed.2018.11.005

2007;**10**:1387-1394

pathologic brain. Nature Neuroscience.

[135] Pender MP, Csurhes PA, Smith C, et al. Epstein-Barr virus-specific T cell therapy for progressive multiple sclerosis. JCI Insight. 2018;**3**. DOI:

10.1172/jci.insight.124714

Immunology. 2015;**4**:e32

[136] Cohen JI. Epstein-Barr virus vaccines. Clinical & Translational

[125] Liddelow SA, Barres BA. Reactive astrocytes: Production, function, and therapeutic potential. Immunity.

[126] Liddelow SA, Guttenplan KA, Clarke LE, et al. Neurotoxic reactive astrocytes are induced by activated microglia. Nature. 2017;**541**:481-487

[127] Sankowski R, Mader S, Valdés-Ferrer SI. Systemic inflammation and the brain: Novel roles of genetic, molecular, and environmental cues as drivers of neurodegeneration. Frontiers in Cellular Neuroscience. 2015;**9**. DOI:

[128] Aloisi F, Pujol-Borrell R. Lymphoid neogenesis in chronic inflammatory diseases. Nature Reviews. Immunology.

[129] Pikor NB, Prat A, Bar-Or A, et al. Meningeal tertiary lymphoid tissues and multiple sclerosis: A gathering place for diverse types of immune cells during CNS autoimmunity. Frontiers in Immunology. 2016;**6**. DOI: 10.3389/

10.3389/fncel.2015.00028

2006;**6**:205-217

fimmu.2015.00657

[130] Corcione A, Casazza S, Ferretti E, et al. Recapitulation of B cell differentiation in the central nervous system of patients with multiple sclerosis. PNAS.

[131] Ahmed W, Tariq S, Khan G. Tracking EBV-encoded RNAs (EBERs) from the nucleus to the excreted exosomes of B-lymphocytes. Scientific

2004;**101**:11064-11069

Reports. 2018;**8**:15438

2015;**47**:1107-1113

[132] Moutsianas L, Jostins L, Beecham AH, et al. Class II HLA interactions modulate genetic risk for multiple sclerosis. Nature Genetics.

**116**

## *Edited by Stavros J. Baloyannis*

Multiple sclerosis is among the most frequent neurological diseases, which affect seriously the quality of life of a constantly increasing number of patients, inducing physical and mental invalidism with indefinite perspectives. The ongoing investigation of the pathogenetic background and the inconclusive analysis of many pathophysiological mechanisms and serious neuropathological alterations of the disease are dominant crucial topics in the field of neurosciences, aimed at tracing a definite way to a therapeutic approach. The authors of this volume attempt to throw light on the labyrinth of multiple sclerosis, approaching the disease from the viewpoint of epidemiology, autoimmune reactions, symptomatology, mental and physical decline, diagnostic procedures, prognosis, and treatment. The authors submit herein, along with scientific data, their hope of contributing effectively to ameliorating the quality of life of those suffering from multiple sclerosis who wait patiently for the day of recovery.

Published in London, UK © 2020 IntechOpen © Ralwel / iStock

Multiple Sclerosis

Multiple Sclerosis

*Edited by Stavros J. Baloyannis*