• HHV-6;
  • β-interferon;
  • multiple sclerosis;
  • nested PCR

Objectives – The aim of this study is to determine the DNA prevalence of different members of Herpesviridae in multiple sclerosis (MS) patients and to describe the possible effect of β-interferon treatment on such prevalence. Material and methods – With a nested polymerase chain reaction (PCR) assay we have studied the DNA of the peripheral blood mononuclear cells (PBMCs) of 204 whole blood samples, [102 from patients with relapsing-remitting MS (RRMS), of which 62 were treated with β-interferon, and 102 from healthy blood donors]. Results – We only found a statistically significant difference for human herpesvirus type 6 (HHV-6) DNA prevalence (< 0.0001): HHV-6 is 2.26 times more frequent in MS patients than in healthy donors. There was no difference in the HHV-6 prevalence between β-interferon treated and untreated patients. Conclusion – 1. Among the herpesviruses, HHV-6 was the only one showing altered prevalence. This either indicates that HHV-6 is involved in the pathogenesis of MS, or it simply indicates that MS influences latency or reactivation of HHV-6 without any direct involvement of HHV-6 in the disease process of MS. 2. Treatment with β-interferon does not make a difference on the DNA prevalence of the herpesviruses studied in our MS patients.