In a previous study, we demonstrated the presence in SPMS brains of latently EBV-infected cells co-expressing LMP2A and PD-L1, of EBV-specific cytotoxic CD8+ T cells expressing PD-1, and the establishment of close contact among them, suggestive of intracerebral functional interactions, possibly aimed at holding the immune system in check during latent infection. This evidence concerns the gene CD274 and disease arising from reactivation of latent virus.