Association of human herpesvirus 6 and 8 in relapsing remitting multiple sclerosis type during exacerbation

Abstract

Multiple Sclerosis (MS) is a chronic demyelinating disease of the CNS with assumed autoimmune etiology. Human herpes viruses have probable effects on relapsing-remitting MS pathogenesis presumably through molecular mimicry and/or bystander mechanisms. In this study we probed the possible contribution of the two herpes viruses, human herpesvirus 6 (HHV-6) and human herpesvirus 8 (HHV-8), in clinically definite MS (CDMS)-relapsing remitting type (RRMS) during clinical exacerbations. All patients had no history of immunomodulating or suppressing drugs intake in prior 6 months. The peripheral blood samples, from CDMS patients (n=20) (13F/7M, age (y) = 30.3±3.21) and other immune mediated neurological disorders (OIND) (11F/9M, age = 25.2±12.1), (Myasthenia Gravis, Guillain Barré Syndrome, ischemic stroke in adolescent and young adult with no clear risk factors), as a control group, had been enrolled within 15 months (January-2007 -- March-2008). We investigated the existence of specific deoxyribonucleic acid (DNA) sequences belonging to HHV-6 and HHV-8, using polymerase chain reaction (PCR) in the isolated peripheral blood mononuclear cells (PBMCs) and in plasma. PCR demonstrated HHV-6 DNA in 7 cases (35%), HHV-8 sequences in only one cases (5%) in PBMCs from 20 relapsed CDMS patients; all HHV-6 positive cases showed positive plasma results, while the blood samples from 20 OIND patients showed negative results except one case (5%) out of 9 cases of GBS was positive for HHV-8 in PBMCs. We consequently concluded that there is considerable evidence in this study that proposed the roles of HHV-6 and HHV-8 in MS pathogenesis and clinical exacerbation.