[Recognition of viral nucleic acids and regulation of type I IFN expression].

Recognition of viral nucleic acids with pattern recognition receptors (PRRs) is the first step to induce innate immune system. Type I interferons (IFNs), central mediators in the antiviral innate immunity, are responsible for induction of cytokines and chemokines that disrupt virus replication. Recent studies indicated that there are at least two distinct pathways for the induction of type I IFN by viral infection. Toll-like receptors (TLRs) are extracellular and endosomal PRRs for microbial pathogens whereas retinoic acid inducible gene-I(RIG-I) and melanoma differentiation-associated gene 5(MDA5) are novel intracellular PRRs for viral dsRNA. In this report we describe the distinct mechanisms inducing type I IFNs through TLRs and RIG-I/MDA5 pathways.