Antiviral innate immune response of RNA interference

RNA interference (RNAi) is an ancient, natural process conserved among species from different kingdoms. RNAi is a transcriptional and post-transcriptional gene silencing mechanism in which, double-stranded RNA or hairpin RNA is cleaved by an RNase III-type enzyme called Dicer into small interfering RNA duplex. This subsequently directs sequence-specific, homology dependent, Watson-Crick base-pairing post-transcriptional gene silencing by binding to its complementary RNA and initiating its elimination through degradation or by persuading translational inhibition. In plants, worms, and insects, RNAi is the main and strong antiviral defense mechanism. It is clear that RNAi silencing, contributes in restriction of viral infection in vertebrates. In a short period, RNAi has progressed to become a significant experimental tool for the analysis of gene function and target validation in mammalian systems. In addition, RNA silencing has then been found to be involved in translational repression, transcriptional inhibition, and DNA degradation. RNAi machinery required for robust RNAi-mediated antiviral response are conserved throughout evolution in mammals and plays a crucial role in antiviral defense of invertebrates, but despite these important functions RNAi contribution to mammalian antiviral innate immune defense has been underestimated and disputed. In this article, we review the literature concerning the roles of RNAi as components of innate immune system in mammals and how, the RNAi is currently one of the most hopeful new advances toward disease therapy. This review highlights the potential of RNAi as a therapeutic strategy for viral infection and gene regulation to modulate host immune response to viral infection.