Human herpesvirus-6 (HHV-6) infection in multiple sclerosis: a preliminary report

We examined cerebral spinal fluid (CSF) from multiple sclerosis (MS) Patients and patients with other neurological diseases (OND) for antibody specific for Human Herpesvirus-6 (HHV-6) and for HHV-6 DNA detectable by PCR CSF from MS patients had a higher frequency of IgG antibody to HHV-6 late antigens (39.4%) compared with CSF from OND (74%). In contrast, the frequency of detectable IgG antibody in CSF from MS patients specific for Epstein-Barr Virus (EBV) (12.1%) and Human Cytomegalovirus (HCMV) (6.1%) was much lower. Two of 12 MS CSFs (16.7%) also contained HHV-6 DNA detected by PCR None of four OND CSF were positive for HHV-6 DNA. Plasma from 16 patients with MS, eight with OND and 72 healthy donors were tested for antibodies by ELISA to HHV-6 early (p41/38) and late (gp110) proteins. Although no differences in anti-gp110 IgG antibody were detected between MS patients, patients with other neurological diseases, and normals IgG antibody to early protein p41/38 was detected in >68% of the plasma from MS patients 12.5% from OND patients and 27.8% of the controls IgM antibody to p41/38 was present in >56% of MS patients, 12.5% of OND patients, and 19% of controls These data suggest that more than half of the MS patients had active, ongoing HHV-6 infections. HHV-6 was also isolated from peripheral blood mononuclear cells (PBMC) from 3/5 MS patients who were in relapse or had progressive disease and was identified as HHV-6 Variant B. These preliminary results support the hypothesis that HHV-6 may be a co-foctor in the pathogenesis of some cases of MS.