IFIH1 and viral infectious disease: N-7 methylation of the 5’-guanosine is essential for viral infection (18, 19), whereas 2’-O methylation is required for evasion of recognition by host immune sensors, notably RIG-I (retinoic acid-inducible gene I) (13, 20, 21), MDA5 (melanoma differentiation-associated protein 5) (12), and IFIT1 or IFIT5 (IFN-induced protein with tetratricopeptide repeats-1 or -5) (22–24).