Absence of HHV-6 and HHV-7 in cerebrospinal fluid in relapsing-remitting multiple sclerosis

To contribute to clarifying the controversy on the association between Human Herpesviruses 6 and 7 (HHV-6, HHV-7) and multiple sclerosis (MS) studying patients with relapsing-remitting MS (RRMS) with or without evidence of disease activity (clinically or radiologically evaluated).

In 25 RRMS patients, 7 suspected MS patients and 9 patients with other neurological diseases, the following parameters were analysed: i) antibody titers (IgM and IgG) against HHV-6 by indirect immunofluorescence both in serum and cerebrospinal fluid (CSF) samples; ii) PCR-detection of HHV-6 DNA and HHV-7 DNA in CSF and HHV-6 DNA in peripheral blood mononuclear cells (PBMCs). MS patients in remission underwent a gadolinium-enhanced magnetic resonance imaging in proximity of sample collections.

No viral DNA was found in any CSF sample, HHV-6 DNA frequency in PBMCs of MS patients and controls was not statistically different. Antibody titers against HHV-6 were comparable to those of the general population. Some 30.4% of MS patients were seronegative to HHV6.

Our data suggest that there is no relationship between HHV-6 or HHV-7 and MS.