BST2 and viral infectious disease: Bone marrow stromal cell antigen 2 (BST2) is expressed in numerous cells, including hepatocytes, plasma blast cells, early plasma cells, mature B cells, dendritic cells, pneumocytes, monocytes, pancreatic cells, kidney cells, and vascular endothelial cells, suggesting that it plays vital roles in the innate immune response against viral infection and other physiological processes (26, 27).