CD274 and Epstein-Barr virus infection: EBV infection can induce DNA demethylation of host cells, which results in expression of tumor suppressor genes, loss of tumor-related antigens, and over-expression of immune checkpoint like PD-L1 and PD-L2 and induces immune evade of Epstein–Barr virus-associated gastric cancer (EBVaGC) by PD-1/PD-L1 interactions between tumor cells and T cells (99, 100).