Although viruses are detected by other PRRs than TLR4 (TLR3, 7, 8, RIG-I), in the more severe outcomes of viral infection such as acute lung injury (ALI), TLR4 signaling is crucially involved through the generation of oxidized phospholipids (OxPAPC) which can also activate TLR4 [25]. Here, TLR4 is linked to viral infectious disease.