One of the most important cellular defenses against RNA viruses is a large, multidomain protein known as RIG-I (Retinoic Acid Inducible Gene I), which functions as a pattern recognition receptor (PRR) that triggers early innate immune responses in vertebrate cells. 1-3 RIG-I is a member of a conserved family of double-stranded RNA (dsRNA) binding proteins that includes additional innate immune surveillance proteins MDA5 and LGP2. [3][4][5] By recognizing and responding to different types of viral RNA motifs, this family (known as the RIG-I-like receptors or RLRs) provides broad protection against viral infections. These proteins are, in turn, closely related to members of the broader Dicer family, such as DRH3 (Dicer related helicase 3), as all of these proteins share a distinctive set of dsRNA binding domains, and an ATPase core that is catalytically activated only upon binding of dsRNA. 6,7 This link between RLRs and Dicer-like proteins involved in miRNA processing suggests a shared evolutionary heritage and the possibility of cross-talk between these two systems. 5 The helicase core of the RLR/Dicer family proteins (previously termed DRAs) is distinct, 7 but identifiable as a member of Helicase Superfamily 2

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