Effective suppression of replication of porcine reproductive and respiratory syndrome virus by adenovirus-mediated small interfering RNAs targeting ORF1b, 5 and 7 genes

Porcine reproductive and respiratory syndrome virus has caused hundreds of thousands of deaths in pig farms in many swine-producing areas in the world in recent years. However, at present there is no effective method to prevent and control the disease, and there is a need to develop new antiviral strategies. In this study, four recombinant adenoviruses expressing shRNAs targeting ORF1b, ORF5 and ORF7 were constructed, and it was found that they could down-regulate effectively specific gene expression and inhibit viral replication in MARC-145 cells when compared to the controls. They could also inhibit effectively PRRSV replication in porcine alveolar macrophages. The inhibition effect was dose-dependent and could be sustained for at least 96 h in macrophages. In addition, PRRSV replication could be suppressed significantly by shRNA in cells infected previously or simultaneously with PRRSV. The results indicated that the shRNA-expressing rAd5 targeting to various gene regions of PRRSV might be a potential anti-PRRSV strategy.