TLR4 and viral infectious disease: As TRIF was previously shown to interact with IRF-7 (25), and IRF-7 is known as a “master regulator” of type I IFN responses in viral infections (24, 35, 36), we hypothesized that IRF-7 is specifically involved in the TLR4 pathway and is required to trigger the induction of TRIF-dependent type I IFN that, in turn, drives IL-1β production.