Conserved function of bat IRF7 in activating antiviral innate immunity: insights into the innate immune response in bats

Bats are natural hosts for various highly pathogenic viruses, which pose a considerable threat to humans and animals. However, they rarely display signs of disease infection from these viruses. The expression of IRF7-induced IFN-β plays a crucial role in preventing viral infections. However, the role of bat IRF7 during viral infection remains unclear. In this study, we cloned Tadarida brasiliensis IRF7 and discovered that its amino acid sequence was poorly conserved among species. Next, we investigated the expression of bat IRF7 mRNA in Tadarida brasiliensis lung cells (TB 1 Lu) infected with RNA viruses such as Newcastle disease virus (NDV), avian influenza virus (AIV), vesicular stomatitis virus (VSV), and the double-stranded RNA (dsRNA) analogue poly (I:C) and demonstrated that these viral infections significantly upregulated the mRNA expression of bat IRF7. Furthermore, the overexpression of IRF7 in TB1 Lu cells activated the expression of bat innate immune-related genes and inhibited virus replication. Importantly, we observed that bat IRF7 function is highly conserved in avian and mammalian species. Structurally, we revealed that the IRF domain of bat IRF7 is essential for activating IFN-β. In summary, our findings indicate that bat IRF7 has a conserved ability to activate bat antiviral innate immunity. This study provides a theoretical foundation for further understanding the innate immune response in bats.