Preclinical evaluation of an anti-HCV miRNA cluster for treatment of HCV infection.

We developed a strategy to treat hepatitis C virus (HCV) infection by replacing five endogenous microRNA (miRNA) sequences of a natural miRNA cluster (miR-17-92) with sequences that are complementary to the HCV genome. This miRNA cluster (HCV-miR-Cluster 5) is delivered to cells using adeno-associated virus (AAV) vectors and the miRNAs are expressed in the liver, the site of HCV replication and assembly. AAV-HCV-miR-Cluster 5 inhibited bona fide HCV replication in vitro by up to 95% within 2 days, and the spread of HCV to uninfected cells was prevented by continuous expression of the anti-HCV miRNAs. Furthermore, the number of cells harboring HCV RNA replicons decreased dramatically by sustained expression of the anti-HCV miRNAs, suggesting that the vector is capable of curing cells of HCV. Delivery of AAV-HCV-miR-Cluster 5 to mice resulted in efficient transfer of the miRNA gene cluster and expression of all five miRNAs in liver tissue, at levels up to 1,300 copies/cell. These levels achieved up to 98% gene silencing of cognate HCV sequences, and no liver toxicity was observed, supporting the safety of this approach. Therefore, AAV-HCV-miR-Cluster 5 represents a different paradigm for the treatment of HCV infection.