IFIH1 and infection: Following infection, pathogen recognition receptors (PRRs) such as retinoic acid-inducible gene I (RIG-I), melanoma differentiation-associated gene 5 (MDA5), Toll-like receptors (e.g., TLR 3, 4 and 7) and other sensing molecules recognize pathogen-associated molecular patterns (PAMPs) in viral components, such as viral structure proteins or viral nucleic acid.