Antibodies to the Epstein-Barr virus proteins BFRF3 and BRRF2 cross-react with human proteins

We hypothesize that the immune response to Epstein-Barr virus (EBV) drives the autoimmune damage in multiple sclerosis (MS). We investigated whether antibodies to two EBV proteins targeted by MS patients cross-react with self proteins. Using affinity columns, immunoprecipitation, and mass spectrometry, we found that antibodies to the EBV protein BFRF3 cross-react with the cytoplasmic protein septin-9, and antibodies to BRRF2 also bind mitochondrial proteins. Using Western blots and ELISA, we demonstrated that MS patients were more likely to have high levels of antibodies to one or another of these self antigens.