Cloning and characterization of porcine interferon-δ-related genes identified by genomic database screening

Interferon-δ (IFN-δ) belongs to type I IFN. It was first identified by Lefevre in 1993. The porcine interferon-δ (PoIFN-δ)-related sequences were reported in 2009. The IFN-δ-related sequences have not been studied as closely as IFN-α and IFN-β. In this study, we identified 11 functional genes and 7 pseudogenes of the PoIFN-δ-related subtypes from the porcine genome database. Three of these genes were cloned, expressed, and functionally studied. PoIFN-δ-related subtypes can bind to the type I IFN receptors, activate the Janus kinase-signal transduce and activator of transcription (JAK-STAT) signaling pathway, induce IFN stimulate genes, and other cytokines. The antiviral activity of PoIFN-δ-related subtypes varies a lot in different subtypes. Among all the PoIFN-δ subtypes detected, PoIFN-δ8 has the strongest antiviral and immunomodulatory activities.