The Differential Antiviral Activities of Chicken Interferon α (ChIFN-α) and ChIFN-β are Related to Distinct Interferon-Stimulated Gene Expression

Chicken interferon alpha (ChIFN-alpha) and ChIFN-beta are type I IFNs that are important antiviral cytokines in the innate immune system. In the present study, we identified the virus-induced expression of ChIFN-alpha and ChIFN-beta in chicken fibroblast DF-1 cells and systematically evaluated the antiviral activities of recombinant ChIFN-alpha and ChIFN-beta by cytopathic-effect (CPE) inhibition assays. We found that ChIFN-alpha exhibited stronger antiviral activity than ChIFN-beta in terms of inhibiting the replication of vesicular stomatitis virus, Newcastle disease virus and avian influenza virus, respectively. To elucidate the mechanism of differential antiviral activities between the two ChIFNs, we measured the relative mRNA levels of IFN-stimulated genes (ISGs) in IFN-treated DF-1 cells by real-time PCR. ChIFN-alpha displayed greater induction potency than ChIFN-beta on several ISGs encoding antiviral proteins and MHC-I, whereas ChIFN-alpha was less potent than ChIFN-beta for inducing ISGs involved in signaling pathways. In conclusion, ChIFN-alpha and ChIFN-beta presented differential induction potency on various sets of ISGs, and the stronger antiviral activity of ChIFN-alpha is likely attributed to the greater expression levels of downstream antiviral ISGs.