ABSTRACT
Innate immune cells, such as dendritic cells and macrophages, detect invading microorganisms including viruses through a limited number of receptors. Two pathways for the detection of viral nucleic acids have been identified. One is mediated by members of the Toll-like receptor (TLR) family that recognize viral double-stranded RNA, single-stranded RNA, and DNA. The other pathway is utilized by RIG-I-like RNA helicases (RLHs) that detect viral RNA in the cytoplasm. These receptors use specific intracellular adaptor proteins to activate the key IRF and NF-κB transcription factors that promote synthesis of various cytokines required to eliminate infected viruses. This review summarizes recent insights into the antiviral signaling pathways activated by TLRs and RLHs.
