Linking myelin and Epstein-Barr virus specific immune responses in multiple sclerosis: insights from integrated public T cell receptor repertoires

The autoimmune responses in multiple sclerosis (MS), particularly those mediated by T cells targeting CNS-derived antigens, are broadly recognized. However, the defining triggers underlying these responses remain poorly understood. Epstein-Barr virus (EBV) infection has emerged as a primary risk factor for MS, suggesting a potential role for molecular mimicry in which EBV-specific immune responses cross-react with myelin antigens. In this study, we analyzed the T cell receptor (TCR) repertoires of MS patients (n = 129) and controls (n = 94) from public datasets, to explore the relationship between EBV-specific and myelin-specific T cell responses. Our analysis identified clusters of TCRs that were significantly depleted among MS patients, many of which were associated with cytomegalovirus (CMV). By generating a library of myelin-reactive TCRs from stimulated peripheral blood mononuclear cells (PBMCs) obtained from MS patients and mapping these sequences to the public TCR repertoire database, we also uncovered a lower frequency of myelin-reactive TCRs in MS samples compared to controls in the public datasets. In addition, epitope-specificity prediction revealed a broader response to EBV-, but not CMV-derived epitopes. Collectively, these findings underscore the complex role of chronic viral infections in MS. Particularly, they suggest that EBV-specific immune responses contribute to the dysregulation of the immune system in MS patients, potentially through mechanisms of molecular mimicry. While the broader response to EBV-derived epitopes and the lower frequency of myelin-reactive TCRs in MS samples are both associated with the disease, further research is needed to clarify the nature of this relationship. These observations suggest that viral and autoimmune mechanisms may contribute independently or interact in MS pathogenesis.