The innate immune system is responsible for reacting to viral infections through recognition of various viral components. Like toll-like receptor 3 (TLR3), MDA5 recognizes double-stranded (ds) RNA which is a molecular pattern indicative of viral infection. MDA5 and its relative RIG-1 recognize different types of dsRNA, with MDA5 recognizing poly (I:C). MDA5 is a member of the DEAD/DEAH-box RNA helicase family, which all contain the conserved DEAD motif of Asp-Glu-Ala-Asp.
