Evaluation of the humoral response against mycobacterial peptides, homologous to MOG_35–55, in multiple sclerosis patients

Bacillus Calmette-Guérin (BCG) and Mycobacterium avium subspecies paratuberculosis (MAP) have been associated with multiple sclerosis (MS). Clinical data indicates that BCG vaccination exerts anti-inflammatory effects in MS; conversely,MAP is thought to be one of the possible infectious factors responsible of MS through a molecular mimicry mechanism. A peptide-based indirect ELISA was used to detect antibodies against the encephalitogenic myelin oligodendrocyte glycoprotein (MOG)35–55 epitope, and two mycobacterial peptides sharing sequence homology with the latter: MAP_2619c352–361/BCG_1224355–364 and BCG_3329c64–74. Among 40 MS patients and 39 healthy volunteers included in the study, only MOG35–55 was capable of inducing a significantly higher humoral response in MS subjects compared to controls. Indeed, 11 out of 40 MS subjects (27.5%) and only 2 out of 39 controls (5%) were antibody-positive for MOG35–55 (p = 0.01, AUC= 0.65). These findings strengthen the importance ofMOG35–55 inMS pathogenesis. The MAP and BCGMOG-homologues epitopes investigated were not recognized in MS patients. Overall, the results allow us concluding that sharing homology of linear epitopes is necessary but not sufficient to induce antibody-mediated cross-reactivity