Tissue distribution and variant characterization of human herpesvirus (HHV)-6: Increased prevalence of HHV-6A in patients with multiple sclerosis

Human herpesvirus (HHV)-6 has been associated with the pathogenesis of mult iple sclerosis (MS) on the basis of serologic, molecular, and histopatholog ic studies. This study sought to determine the distribution of HHV-6 in dif ferent MS body fluids, including serum, saliva, urine, and peripheral blood lymphocytes. The study results extend the observation of an increased freq uency of HHV-6 DNA in serum of patients with MS to the unique detection of viral sequences in urine of a subset of patients with MS. Moreover, the HHV -6 identified in these cell-free compartments was predominantly the HHV-6A variant, which has been reported to be neurotropic. These results support t he hypothesis that HHV-6 may contribute to the MS disease process.