RIG-I (retinoic acid-inducible gene 1) is a RIG-I-like receptor dsRNA helicase enzyme that is encoded (in humans) by the DDX58 gene. RIG-I is part of the RIG-I-like receptor family, which also includes MDA5 and LGP2, and functions as a pattern recognition receptor that is a sensor for viruses such as influenza A, Sendai virus, and flavivirus. Certain retroviruses, such as HIV-1, encode a protease that directs RIG-1 to the lysosome for degradation, and thereby evade RIG-1 mediated signaling. RIG-I typically recognizes short (< 4000nt) 5′ triphosphate uncapped double stranded or single stranded RNA. RIG-I and MDA5 are involved in activating MAVS and triggering an antiviral response. RIG-I is also able to detect non-self 5′-triphosphorylated dsRNA transcribed from AT-rich dsDNA by DNA-dependent RNA polymerase III (Pol III). For many viruses, effective RIG-I-mediated antiviral responses are dependent on functionally active LGP2.