We are not sure whether the induction of potent type I IFN innate responses in the absence of TLR4 signal pathway was mediated directly by enhanced signal transduction of other PRRs, such as TLR3, RIG-I, and MDA5, and/or indirectly by soluble factors produced from host cells by viral infection, i.e. DAMPs. Here, TLR4 is linked to viral infectious disease.