IFIT1 and viral infectious disease: IFIT (IFN-induced protein with tetratricopeptide repeats (TPRs))-family proteins contain four members in humans, namely IFIT1 (ISG56), IFIT2 (ISG54), IFIT3 (ISG60) and IFIT5 (ISG58), and are induced to high levels in response to IFN signaling and/or viral infections [69].