Interferon-beta, interferon-gamma and their fusion interferon of Siberian tigers (Panthera tigris altaica) in China are involved in positive-feedback regulation of interferon production

As a group of cytokines, interferons are the first line of defense in the antiviral immunity. In this study, Siberian tiger IFN-β (PtIFN-β) and IFN-γ (PtIFN-γ) were successfully amplified, and the two were fused (PtIFN-γ) by overlap extension polymerase chain reaction (SOE-PCR). Bioinformatics analysis disclosed that PtIFN-β and PtIFN-γ have species-specificity and conservation in the course of evolution. After being expressed in prokaryotes, the antiviral activities and physicochemical properties of PtIFN-β, PtIFN-γ and PtIFNβ-γ were analyzed. In Feline kidney cells (F81), PtIFNβ-γ showed more active antiviral activity than PtIFN-β and PtIFN-γ, which has more stable physicochemical properties (acid and alkali resistance, high temperature resistance). In addition, PtIFN-β, PtIFN-γ and PtIFN-γ activated the JAK-STAT pathway and induced the transcription and expression of interferon-stimulated genes (ISGs). Janus kinase (JAK) 1 inhibitor inhibited ISGs expression induced by PtIFN-β, PtIFN-γ and PtIFN-γ. Overall, this research clarified that PtIFN-β, PtIFN-γ and PtIFNβ-γ have the ability to inhibit viral replication and send signals through the JAK-STAT pathway. These findings may facilitate further study on the role of PtIFN in the antiviral immune response, and help to develop approaches for the prophylactic and therapeutic of viral diseases based on fusion interferon.