IFIH1 and viral infectious disease: The domain architecture of chicken MDA5 comprises two caspase recruitment domains (CARDs), a restriction enzyme domain type 3 (RES III), a helicase conserved C-terminal domain (helicase-C), and a retinoic acid-inducible gene I C-terminal regulatory domain (RIG-I-C-RD) (Lee et al., 2012) During a viral infection, MDA5 detects viral RNA that has a helicase domain and transmits a signal via CARDs.