Human Herpesvirus 6 and Multiple Sclerosis: A One-Year Follow-up Study

Abstract

Background. This study was undertaken in order to investigate the possible relation of HHV‐6 and EBV in relapsing‐remitting MS (RRMS). Materials and methods. A one‐year follow up study was performed analysing peripheral blood mononuclear cells and serum samples of 57 patients with RRMS and 57 healthy blood donors (HBD) by a quantitative real time PCR, to detect HHV‐6 and EBV. Clinical data (starting age and EDSS increase) were collected. Results. We did not find any statistically significant difference for EBV between RRMS patients and HBD. Regarding HHV‐6: i) There was a higher prevalence of HHV‐6 in RRMS patients than in controls: 80.7% versus 29.8% respectively. ii) HHV‐6 active replication seems to be related to exacerbations. iii) Only variant A was detected among RRMS patients with HHV‐6 active replication. iv) Although some difference was found when we compared clinical data in RRMS patients with and without HHV‐6 active replication, the results did not reach statistical significance. Conclusions. A higher HHV‐6A frequency of active infection (reactivation or new infection) would lead to a more frequent exposure of HHV‐6A antigens to the immune system of RRMS patients; this active replication of HHV‐6A seems to be specifically related with the exacerbations in a subset of RRMS patients.