Viperin has been identified as a human cytomegalovirus and IFN-γ inducible protein. Its expression is activated by both TLR3-dependent and RIG-I-dependent pathways. Viperin inhibits influenza A virus release of infected cells by altering plasma membrane fluidity and the formation of lipid rafts. It acts on the lipid rafts by decreasing the activity of the enzyme farnesyl diphosphate synthase (FPPS) which is essential for isoprenoid biosynthesis.