Intrathecal human herpesvirus 6 antibodies in multiple sclerosis and other demyelinating diseases presenting as oligoclonal bands in cerebrospinal fluid

Demyelinating diseases of the central nervous system (CNS) often include elevated IgG production in intrathecal space presenting as oligoclonal bands (OCBs) in cerebrospinal fluid (CSF). In most demyelinating diseases, e.g. in multiple sclerosis (MS), the underlying cause is not known. We used isoelectric focusing and affinity immunoblot to study the specificity of CSF OCBs to human herpesvirus-6 (HHV-6) in patients with demyelinating diseases of the CNS including MS. Eighty patients with positive OCB finding were included in the study. The OCBs reacted with the HHV-6 antigen in 18 cases (23%). Twelve of 46 MS patients (26%), 5 of 24 other demyelinating diseases (21%) and 1 of 10 other neurological disorders (10%) had HHV-6 specific OCBs in CSF. A specific intrathecal HHV-6 A and B antibody production was shown in a proportion of patients with demyelinating diseases and might suggest a role in the pathogenesis of these diseases.