Interferon lambda 3 （gene symbol: IFNL3） encodes the IFNL3 protein. IFNL3 was formerly named IL28B. IFNL3 shares ~96% amino-acid identity with IFNL2, ~80% identity with IFNL1 and ~30% identity with IFNL4. Interferon lambda genes encode cytokines classified as type III interferons, which are distantly related to type I interferons and the IL-10 family. Type III interferons are induced by viral infection and interact with a heterodimeric class II cytokine receptor that consists of interleukin 10 receptor, beta （IL10RB） and interferon lambda receptor 1 （IFNLR1） to signal via the JAK-STAT anti-viral pathway.