JC virus antibody status in a pediatric multiple sclerosis cohort: prevalence, conversion rate and influence on disease severity.

Background: Because of the emergence of novel therapies for multiple sclerosis (MS) and the associated increased risk of progressive multifocal leukoencephalopathy, John Cunningham (JC) virus infection has become a focus of interest for neurologists. However, little is known about JC virus infection in pediatric MS to date. Objective: We aimed to analyze the prevalence of anti-JC virus antibodies, the conversion rate and the influence of the anti-JC virus antibody status on the clinical course in a large pediatric MS cohort. Methods: Anti-JC virus antibodies were analyzed in serum samples within six months of disease onset and during the course of the disease. Clinical data were extracted from a pediatric MS databank. Results: A total of 51.6% of 256 patients were found to be positive for anti-JC virus antibodies at onset of disease. No correlation between antibody status and clinical course was seen. Analyzing 693 follow-up serum samples revealed high titer stability, and an annual conversion rate of 4.37% was seen. Conclusion: No evidence was found that seropositivity for anti-JC virus antibodies influences the clinical course. Surprisingly, seroprevalence for anti-JC virus antibodies was more than twice as high as anticipated in this age group, raising the question of whether the infection increases the risk of MS development.