IRF7 in the Australian Black Flying Fox, Pteropus alecto: Evidence for a Unique Expression Pattern and Functional Conservation

As the only flying mammal, bats harbor a number of emerging and re-emerging viruses, may of which cause severe diseases in humans and other mammals yet results in no clinical symptoms in bats. As the master regulator of the interferon (IFN)-dependent immune response, IFN regulatory factor 7 (IRF7) plays a central role in innate antiviral immunity. To explore the role of bat IRF7 in the regulation of IFN response, we performed sequence and functional analysis of IRF7 from the pteropid bat, Pteropus alecto. Our results demonstrate that bat IRF7 retains the ability to bind to MyD88 and activate the IFN response despite unique changes in the MyD88 binding domain. We also demonstrate that bat IRF7 has a unique expression pattern across noth immune and non-immune related tissues and is inducible by double-strand RNA. The broad tissue compared to other mammals. The importance of IRF7 in antiviral activity against the bat reovirus, pulau virus ws confirmed by siRNA knockdown of IRF7 in bat cells resulting in enhanced viral replication. Our results highlight the importance of IRF7 in innate antiviral immunity in bats.