IRF7 and viral infectious disease: Viral induction of IFN-α/β genes is severely impaired in IRF−/− fibroblasts and IRF−/− mice are more vulnerable than Myd88−/− mice to viral infection, and this correlates with a decrease in serum IFN levels, indicating the importance of the IRF7-dependent induction of systemic IFN responses for innate antiviral immunity [28].