High frequency of co-infection by Epstein–Barr virus types 1 and 2 in patients with multiple sclerosis

Abstract

Background: The existence of Epstein–Barr virus (EBV) strains specifically associated with multiple sclerosis (MS) is a matter of controversy. Little is also known about the prevalence of EBV types 1 and 2 in MS patients and the presence of co-infections by both strains. Objective: To make EBV strain type assignment and compare the frequencies of types 1, 2 and co-infections by both in MS patients and healthy controls. Methods: Blood samples from 75 consecutive MS patients and 186 controls were collected. EBV was simultaneously detected and typed using a polymerase chain reaction (PCR) which amplified a strain-specific sequence in the EBV nuclear antigen 2. Results: EBV was detected in 70 out of 75 patients (93.3%) and in 123 of 186 controls (66.1%). Among positive cases, type 1 was found in 6 patients (8.6%) and 40 controls (32.5%), type 2 in 1 patient (1.4%) and 37 controls (30.1%), and dual-infections by both EBV types were detected in 63 patients (90%) and 46 controls (37.4%). Logistic regression models showed that MS was significantly associated with the presence of EBV (p < 0.001) and also with dual type infections (p < 0.001). Conclusion: This study provides molecular evidence associating co-infection of type 1 and 2 EBV with MS.