PDCD1 and cancer: EBV expresses only a limited set of viral genes in cancers, minimizing the presentation of viral antigens and reducing the visibility of the infected cells to the immune system.31 Infected cells may downregulate Major histocompatibility complex (MHC) class I molecules, hindering the presentation of viral antigens to cytotoxic-T-lymphocytes (CTLs).8 EBV can exploit immune checkpoint (IC) pathways, such as the PD-1/PD-L1 axis.