IRF3 and viral infectious disease: IRF3, located in the cytoplasm in an inactive form, appears to be constitutively expressed in cells, which is required for rapid and efficient antiviral innate responses during an early stage of viral infection.272 The activated IRF3 dimer translocates into the nucleus, where it coordinately integrates with several transcription factors for promoters of IFN-I to trigger antiviral innate immunity.