Among a large cohort of patients with early multiple sclerosis (MS), all tested positive for Epstein-Barr virus (EBV), suggesting the infection might be ‘necessary but not sufficient’ for development of the condition, researchers say.

The investigators tested serum from 901 people enrolled in the German National MS cohort, which has strict inclusion criteria to ensure the patient has either clinically isolated syndrome or early relapsing-remitting MS.

All participants (median age 33 years, 70% female) were therapy-naive and had serum collected at their baseline appointment on recruitment into the longitudinal, observational cohort study.

However, serum was only available in small quantities, so it was diluted tenfold and the samples were examined for Epstein-Barr nuclear antigen (EBNA-1) and the EBV viral capsid antigen (VCA) using an automated quantitative chemiluminescence immunoassay.