IFITM3 and viral infectious disease: In the early stages of viral infection, IFITM3 inhibits virus entry into cells, whereas IFI27 is produced in the late stages of viral infection, mediating apoptosis by disrupting mitochondrial membrane stability.62, 63 IFI30 is induced by type II IFN and mainly assists in the antigen presentation process restricted by MHC class II antigens.64