Inhibition of porcine reproductive and respiratory syndrome virus replication in porcine alveolar macrophages with the 3′ UTR-targeted amiRNA

[Objective] To study the inhibitory effect of 3′ untranslated region (UTR)-targeted artificial microRNA (amiRNA) against porcine reproductive and respiratory syndrome virus (PRRSV) replication in porcine alveolar macrophages (PAM). [Methods] Recombinant adenovirus (rAd) expressing the 3′ UTR-targeted or control amiRNA and green fluorescent protein (GFP) reporter gene were generated by transfecting AAV-293 cells with the transfer vector. The expression of sequence-specific amiRNA was detected by quantitative RT-PCR. The anti-PRRSV effect of amiRNA was detected by quantitative RT-PCR, Western blotting and viral titration assay. [Results] Two rAds, namely rAd-amiR3UTR-GFP and rAd-amiRcon-GFP, were generated. Both primary PAM and 3D4/163 cells could be transduced by rAd with different transduction efficiencies. The amiR3UTR was expressed in dose-and timedependent manners in rAd-transduced PAM cells. The amiR3UTR, but not amiRcon, had significant and stable inhibitory effects against replication of three different PRRSV strains in a dose-dependent manner. [Conclusion] The rAd-delivered amiR3UTR had strong anti-PRRSV effect against different PRRSV strains and rAd-amiR3UTR-GFP could be explored further as the alternative strategy against PRRS.