Infection with Epstein–Barr virus (EBV) correlates with the development of systemic lupus erythematosus (SLE) and MS, as SLE and MS patients display higher seroprevalence of EBV compared to healthy controls [14,15] and some autoreactive CD4+ T cell clones can cross-react with EBV peptides [16]. This evidence concerns the gene CD4 and systemic lupus erythematosus.