PDCD1LG2 and Epstein-Barr virus infection: However, since both PD-L1 and PD-L2 were recently reported to be expressed in EBV-positive (but not EBV-negative) gastric cancers [61], which often have type I latency, it is possible that even type I latency EBV infection promotes PD-L1 and/or PD-L2 expression on host cells.