ID: 189: Interferon-induced Ifit proteins: Their role in viral pathogenesis

IFITs, the interferon-induced proteins with tetratricopeptide repeats, are encoded by a family of interferon (IFN)-stimulated genes. There are four human IFITs and three mouse Ifits, whose primary structures are related but distinct. They are strongly induced by both Type I and Type III IFNs; in addition, TLR, RLR or STING signaling pathways, that activate IRFs, can induce these genes without any involvement of IFN. IFITs do not have any known enzyme activities and hence, their cellular activities are mediated by altering the functions of specific cellular proteins and RNAs to which they bind. Recent derivation of Ifit knock-out mouse lines has paved the way for studying their role in viral pathogenesis and such studies have revealed the nature of their antiviral effects in vivo, which are not only virus-specific but tissue-specific as well. Moreover, viruses often use elegant means to evade the actions of Ifits, thereby demonstrating the importance of these proteins’ antiviral functions. It is anticipated that future investigation of additional properties of the Ifit KO mice will reveal new biological functions of these proteins.