Because infections causedby a wide variety of microbial agents can both trigger attacks of MS47, 48, 49 and reactivate EBV infection,50, 51, 52, 53, 54 we hypothesize that expansion of EBV-specificCD4+ T cells and CD8+ T cells during clinicalattacks occurs in response to reactivation of EBV in peripheral lymphoid organs bythe intercurrent infections triggering the attacks. Here, CD8A is linked to Epstein-Barr virus infection.