Human herpesvirus-6 viral load and antibody titer in serum samples of patients with multiple sclerosis

Despite the number of cases with definite diagnosis of multiple sclerosis (MS) being on increase, the role of human herpesvirus-6 (HHV-6) infection as a trigger for MS disease still is deliberated. Based on antibody detection and quantitative HHV-6 polymerase chain reaction assay, this study was achieved to find out the possible association between infection with HHV-6 and clinical progression of MS disease.

A total of 108 serum samples were obtained from 30 MS patients followed prospectively for a 6-month period. These samples were analyzed for the presence of HHV-6 DNA by nested polymerase chain reaction enzyme-linked immunosorbent assay and for anti-HHV-6 IgG titer. Activation of the disease was determined by either magnetic resonance imaging or by clinical status of the patients. Control groups were also included.

The average antibody index for the MS patients in the first sample collection was higher than both control groups (p = 0.001). HHV-6 DNA was detected in the serum samples of 10 of 30 MS patients. The mean HHV-6 viral load in patients with relapsing-remitting multiple sclerosis (RRMS) with and without relapse was 973 and 714, respectively. Seven patients showed an exacerbation during the study period. Of those, four patients had HHV-6 DNA in their collected samples. The prevalence of HHV-6 DNA was significantly higher in patients with MS as compared with control groups (p = 0.001).

The results indicate that HHV-6 is implicated somehow in MS disease. Over time, rising HHV-6 IgG antibody titers together with an exacerbation and detection of HHV-6 DNA in serum samples of some MS patients suggests possible association between the reactivation of the virus and disease progression.