Beschreibung:
<jats:sec><jats:title>Background:</jats:title><jats:p> The antibody reactivity against Epstein-Barr nuclear antigen-1 (EBNA-1), and 25-hydroxyvitamin D (25(OH)D) status have been associated with multiple sclerosis (MS) risk. Interaction between these two factors has been proposed. </jats:p></jats:sec><jats:sec><jats:title>Objectives:</jats:title><jats:p> The objective of this paper is to examine the association between antibody reactivity against EBNA-1 and five EBNA-1 domains, and the risk of MS, and to examine if these antibodies and 25(OH)D status interact regarding MS risk in prospectively collected blood samples. </jats:p></jats:sec><jats:sec><jats:title>Methods:</jats:title><jats:p> Antibody reactivity and 25(OH)D levels were measured using ELISAs in n = 192 MS cases and n = 384 matched controls. The risk of MS was analysed using matched logistic regression. Interaction on the additive scale was assessed. </jats:p></jats:sec><jats:sec><jats:title>Results:</jats:title><jats:p> The risk of MS increased across tertiles of antibody reactivity against EBNA-1, domain EBNA-1<jats:sup>402–502</jats:sup>, and domain EBNA-1<jats:sup>385–420</jats:sup>; p trends < 0.001. In young individuals (below median age at sampling, < 26.4 years), these associations were stronger, and 25(OH)D levels correlated inversely to antibody reactivity against EBNA-1 and the EBNA-1 domains. No statistical interaction was found. </jats:p></jats:sec><jats:sec><jats:title>Conclusions:</jats:title><jats:p> We confirm that increased antibody reactivity against EBNA-1 is a risk factor of MS. 25(OH)D status might influence the immune response towards Epstein-Barr virus in young subjects, and thereby modulate MS risk. </jats:p></jats:sec>