Antiviral activity of interferon beta treatment in multiple sclerosis patients

• Published in: Multiple sclerosis Vol. 14; p. S65
• Main Authors: Garcia-Montojo, M, Alvarez-Lafuente, R, Dominguez-Mozo, MI, De las Heras, V, Bartolome, F M, Arroyo, R
• Format: Journal Article
• Language: English
• Published: 01.09.2008
• Subjects: Epstein-Barr virus; Herpesvirus; Human herpesvirus 6
• ISSN: 1352-4585

Background: Viral infections have been appointed as the main component of environmental susceptibility to multiple sclerosis (MS). Interferon beta has antiviral, immunomodulatory and antiprolifera-tive properties and it is able to modify the natural course of the disease. Objective: To analyze the antiviral activity of interferon beta and to correlate it with its clinical efficiency in MS patients treated with interferon beta 1b for two years. Methods: Pairs of blood and serum samples were collected from 54 MS patients along seven programmed visits in two years: one before the start of the treatment (basal visit) and six during interferon beta treatment. In the case of relapse, another pair of samples was collected. Human herpes virus 6 (HHV6) and Epstein-Barr virus (EBV) genomes were detected by quantitative polymerase chain reaction (qPCR). Results: HHV-6 prevalence in blood samples decreased from 66.6% at basal visit to 40% at 24 months (p=0.0001). In serum samples, it decreased from 18% to 10.3% along the study period (p=0.1). Moreover, in healthy blood donors, the HHV-6 prevalence in blood was 22.1% (p=0.005), whereas in serum no positive sample was found (p=0.001). EBV prevalence in blood only presented slight differences between visits. Any positive sample was found in the serum. Moreover, we also found that in samples obtained at non-programmed visits from patients in relapse the prevalence of HHV-6 was significantly higher than in programmed visits: 81.8% in blood (p=0.009), 63.3% in serum (p<0.001). Regarding EBV, its prevalence in relapses did not differ from samples in remission (p<0.001). Furthermore, 55.5% of patients with reactivations of HHV-6 experienced at least one relapse during the follow up versus 13.9% of patients without viral reactivations. Conclusions: Clinical efficiency of interferon beta treatment seems to be linked to its antiviral activity against HHV-6, suggesting a possible role of this virus in the pathogenesis of MS.