Several downstream signaling pathways activated by virus infection, such as JAK/STAT, MAPK, and NF-κB signaling, are involved in both TLR agonists- and virus infection-mediated regulation of PD-L1 (114, 137, 138, 159, 161, 166), further supporting the notion that TLR signaling serves as an effector for the induction of PD-L1 upon virus infection. This evidence concerns the gene NFKB1 and viral infectious disease.