MicroRNA-mediated interactions between host andhepatitis C virus

Micro RNAs(mi RNAs) are small noncoding RNAs. More than 2500 mature mi RNAs are detected in plants, animals and several types of viruses. Hepatitis C virus(HCV), which is a positive-sense, singlestranded RNA virus, does not encode viral mi RNA. However, HCV infection alters the expression of host mi RNAs, either in cell culture or in patients with liver disease progression, such as liver fibrosis, cirrhosis, and hepatocellular carcinoma. In turn, host mi RNAs regulate HCV life cycle through directly binding to HCV RNAs or indirectly targeting cellular m RNAs. Increasing evidence demonstrates that mi RNAs are one of the centered factors in the interaction network between virus and host. The competitive viral and host RNA hypothesis proposes a latent cross-regulation pattern between host m RNAs and HCV RNAs. High loads of HCV RNA sequester and de-repress host mi RNAs from their normal host targets and thus disturb host gene expression, indicating a means of adaptation for HCV to establish a persistent infection. Some special mi RNAs are closely correlated with liver-specific disease progression and the changed levels of mi RNAs are even higher sensitivity and specificity than those of traditional proteins. Therefore, some of them can serve as novel diagnostic/prognostic biomarkers in HCVinfected patients with liver diseases. They are also attractive therapeutic targets for development of new anti-HCV agents.