Herpes virus 6 linked to MS relapses

Epub ahead of print: Simpson et al. Anti-HHV-6 IgG titer significantly predicts subsequent relapse risk in multiple sclerosis. Mult Scler. 2011 Nov 14.

Background: Some of the strongest associations with MS onset are for human herpesviruses, particularly Epstein-Barr virus (EBV) and human herpesvirus 6 (HHV-6). Their role in MS clinical course is less clear, however.

Methods: Prospective cohort of 198 persons with clinically definite MS, followed 2002-5, and serum samples obtained from all subjects at study entry to measure anti-HHV-6 and anti-EBV (Epstein-Barr nuclear antigen [EBNA] and viral capsid antigen [VCA]) antibody Immunoglublin G (IgG) levels (titers).


Results: For the 145 persons with RRMS followed beyond one review, anti-HHV-6 IgG titer was positively associated with the hazard of relapse with a dose-dependent trend (p = 0.003), not affected by adjustment for anti-EBV IgG titers, neither of which were independently associated with relapse. There was no significant association between anti-human herpesvirus IgG titers and baseline-measured disability scores, or change in disability scores; however, anti-HHV-6 IgG titers were 2.8 times higher among progressive-course females than progressive-course males.

Discussion: These findings suggest that, in addition to a potential etiological role in MS, HHV-6 infection or the immune response to HHV-6 antigens may have an effect on the risk of MS relapses and possibly on progressive courses of MS. The observed effect was directly related to anti-HHV-6 IgG titers and may indicate that either HHV-6 infection or factors associated with an altered humoral immune response to HHV-6 may have an effect on MS clinical course. Anti-HHV-6 IgG titer may be a useful factor in assessing the course of relapsing-remitting MS clinical course.

HHV6 is another common virus that may of us are exposed to. It further adds to the belief that relapses often follow (upper respiratory tract-lung) infections

"The problem I have with this study is that antibodies to HHV-6 actually recognise two different viruses called HHV-6A and HHV-6B; these viruses although similar to each other are different. What virus is therefore responsible for this association?"

"How does this tie in with the EBV hypothesis? Could other herpes viruses be linked to MS? These questions all need answering and I think about them a lot."

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