RNA interference of influenza A virus replication by microRNA-adapted lentiviral loop short hairpin RNA.

Limitations of the current vaccines and antivirals against influenza A virus (IAV) pandemic underscore the urgent need for developing novel anti-influenza strategies. RNA interference (RNAi) induced by small interfering RNA (siRNA) has become a powerful new means to inhibit viral infection in a gene-specific manner. However, the efficacy of the siRNA delivery platform and the relatively high cost of administration have hindered widespread application of siRNA. In this study, we developed a microRNA (miRNA)-30-based lentivirus delivery system by embedding a synthetic short hairpin RNA (shRNA) stem into the context of endogenous precursor of miRNA-30 (shRNAmir) to express a silencer of the influenza gene. We showed that the miRNA-based lentivirus vector was able to express and process a single nucleoprotein (NP)-targeting shRNAmir, which could potently inhibit IAV replication. We further showed that miRNA-based lentivirus vector carrying tandemly linked NP and polymerase PB1 shRNAmirs could express and process double shRNAmirs. Despite the relatively low levels of NP and PB1 miRNAs produced in the stably transduced cells, the combination of two miRNAs exerted a great degree of inhibition on influenza infection. Given the advantage of combinatorial RNAi in preventing emergence of mutant virus, miRNA-based lentiviral vectors are valuable tools for anitiviral activities. To the best of our knowledge, this is the first study demonstrating that a miRNA-based RNAi strategy can be applied for better control of influenza virus infection.