What is the role of viral illness in multiple sclerosis (MS)?

Updated: Oct 08, 2019
  • Author: Christopher Luzzio, MD; Chief Editor: Jasvinder Chawla, MD, MBA  more...
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Answer

Another hypothesis is that a virus may infect the immune system, activating self-reactive T cells (myelin reactive) that would otherwise remain quiescent. A virus that infects cells of the immune and nervous systems can possibly be reactivated periodically and thus lead to acute exacerbations in MS.

Epstein-Barr virus (EBV) infection has been found to become periodically reactivated, but a possible causative role in MS has been difficult to prove. Evidence supporting EBV infection as an etiologic factor includes (1) long-term studies showing a higher association with MS in individuals with early presence of serum antibodies against specific EBV antigens and (2) high expression of EBV antigens within MS plaques. [37]

Evidence that argues against an etiologic role for EBV infection includes the fact that MS is a highly heterogeneous disease; EBV might help trigger some cases but not others, making associations in populations difficult. In addition, it is possible that EBV reactivation is an effect rather than a cause (ie, instead of viral reactivation being the trigger for MS, reactivation might be an epiphenomenon of a dysregulated immune system).


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