Toll-like receptors(TLRs)are type I transmembrane proteins that are important components of innate immunity and play essential roles in inducing acquired immune responses[1].These proteins consist of three parts:the cytoplasmic domain,transmembrane domain,and extracellular domain.The extracellular domain is com-posed of 18-33 leucine-rich repeat(LRR)sequences that enable the host to specifically recognize pathogen-associated molecular patterns and are the core of TLR recognition ligands[2].The cytoplasmic domain is homologous with the interleukin 1 recep-tor(IL-1R)family and known as the Toll-IL-1 receptor homol-ogy domain,which is highly conserved and plays a key role in signal transduction[1].TLR3 recognizes viral dsRNA during immune protection from viruses[3].After the host is infected by a virus,the LRR region of TLR3 recognizes the viral dsRNA,and the Toll/IL-1 receptor(TIR)domain recruits the adaptor pro-tein TIR domain-containing molecule 1(also known as TRIF)for signal cascade transmission[4].The activation of TLR3 finally leads to cytokine secretion,especially the production of type I interferon[4].