Functional characterization of bat IRF1 in IFN induction.

Bats are natural hosts for various zoonotic viral diseases. However, they rarely show signs of disease infection with such viruses. During viral infection, members of the IRFs family induce the production of IFNβ and exert antiviral effects. However, the functions of bat interferon regulatory factors (IRFs) remain unclear. In this study, the Tadarida brasiliensis IRF1 (TbIRF1) gene was first cloned and a series of bioinformatics studies were conducted. Results showed that bat IRF1 protein sequence showed a low similarity with IRF1s from other species. RNA virus such as Newcastle disease virus (NDV-GFP), avian influenza virus (AIV) and vesicular stomatitis virus (VSV-GFP) infection of Tadarida brasiliensis 1 lung (TB 1 Lu) cells significantly promotes the expressions of IFNβ, PKR, and OAS1, and up-regulates the expression of TbIRF1. Overexpression of TbIRF1 markedly activates IFNβ promoter activity in a dose-dependent manner. Next, we constructed the TbIRF1 functional domain deletion plasmids and found that the DNA binding domain (DBD) is necessary for TbIRF1 to induce IFNβ expresison. In conclusion, the first bat IRF1 gene was cloned, and its functions in IFN induction were preliminarily identified.