No evidence of an association of multiple sclerosis (MS) with Borna disease virus 1 (BoDV-1) infections in patients within an endemic region: a retrospective pilot study

Background: Borna disease virus 1 (BoDV-1) causes rare human infections within endemic regions in southern and eastern Germany. The infections reported to date have been linked to severe courses of encephalitis with high mortality and mostly irreversible symptoms. Whether BoDV-1 could act as a trigger for other neurological conditions, is, however, incompletely understood. Objectives and methods: In this study, we addressed the question of whether the presentation of a clinically isolated syndrome (CIS) or of multiple sclerosis (MS) might be associated with a milder course of BoDV-1 infections. Serum samples of 100 patients with CIS or MS diagnosed at a tertiary neurological care center within an endemic region in southern Germany and of 50 control patients suffering from headache were retrospectively tested for BoDV-1 infections. Results: In none of the tested sera, confirmed positive results of anti-BoDV-1-IgG antibodies were retrieved. Our results support the conclusion that human BoDV-1 infections primarily lead to severe encephalitis with high mortality.