Monitoring of active human herpes virus 6 infection in Iranian patients with different subtypes of multiple sclerosis.

Background. Recently, it has been suggested that human herpes virus 6 (HHV6) may play a role in the pathogenesis of multiple sclerosis (MS). Our purpose is to determine the incidence of reactivated HHV6 in MS patients. Methods. Viral sequence analyzed by qPCR in the peripheral blood mononuclear cells (PBMCs), serum, and saliva samples of different subtypes of MS patients (n = 78) and healthy controls (n = 123). HHV6 IgG and IgM antibody levels measured by ELISA technique in the plasma samples of both groups. Likewise, cerebrospinal fluid (CSF) samples of some MS patients (n = 38) were analyzed for viral sequence. Results. Results demonstrate increased levels of anti-HHV6-IgG (78.2% versus 76.4% in controls; P = NS), and IgM (34.6% versus 6.5% in controls; P < 0.05) in MS patients. Furthermore, RRMS and SPMS patients showed relatively higher anti-HHV6 IgG and IgM compared to PPMS (P < 0.001). Moreover, load of cell-free viral DNA was higher in RRMS and SPMS patients and detected in 60.2% (47/78) of MS patients, compared with 14.6% (18/123) of healthy controls (P < 0.001). Moreover, load of cell-free viral DNA was higher in RRMS and SPMS patients and detected in 60.2% (47/78) of MS patients, compared with 14.6% (18/123) of healthy controls (P < 0.001). Conclusions. The results extend the observation of an increased frequency of systemic reactivated HHV6 infection in MS patients with developed stages of disease.