RNA Viruses: RNA Roles in Pathogenesis, Coreplication and Viral Load

Poltronieri, Palmiro; Sun, Binlian; Mallardo, Massimo

Plants and lower eukaryotes produce miRNAs and siR-NAs as a form of RNA-interference (RNAi) to restrict infecting viruses. While mammals conserve the same functional miRNA repertoire and RNA-silencing machinery, some have debated whether they employ a miRNA-based antiviral strategy. For endogenous mammalian retroviruses, there is a large body of literature demonstrating that a variety of small non-coding RNA forms are employed to silence these elements. In silico analyses have also indicated that exogenous mammalian viruses may be similarly susceptible to miRNA-based restriction. The notion that miRNAs restrict viruses in mammals as they do in invertebrate or plant cells is supported by increasing examples of RNAi-silencing suppressors encoded by mammalian viruses such as Adenovirus, HCV, Ebola, Influenza A virus, primate foamy virus, HIV, SARS corona virus and HTLV-1. Further investigation is needed to understand how RNA-based and protein-based viral restriction mechanisms cooperate together in human cells.