Porcine reproductive and respiratory syndrome (PRRS) is a serious infectious disease in the swine industry, which causes severe economic losses to current swine production worldwide. There are no effective antiviral strategies for preventing this disease. Previous studies showed that microRNAs (miRNAs) play important role in virus-host interactions. In this study, we demonstrated that the expression level of ssc-miR-124a was significantly downregulated during both high and low pathogenic PRRSV infection. Overexpression of ssc-miR-124a markedly inhibits PRRSV replication in PAMs. Luciferase reporter experiments and RISC immunoprecipitation assay were used to identify the ssc-miR-124a could directly target the 3’UTR of pig CD163 mRNA in a sequence-specific manner and that CD163 mRNA and protein levels were reduced in PAMs overexpressing ssc-miR-124a. These data not only provide new insights into virus-host interactions during PRRSV infection, but also suggest potential new antiviral strategies against PRRSV infection in the future.

猪繁殖与呼吸综合征（PRRS）是养猪业的一种严重传染病，给当前全球养猪业造成严重的经济损失。没有有效的抗病毒策略来预防这种疾病。先前的研究表明，microRNA (miRNA) 在病毒-宿主相互作用中发挥着重要作用。在这项研究中，我们证明 ssc-miR-124a 的表达水平在高致病性和低致病性 PRRSV 感染期间均显着下调。ssc-miR-124a 的过表达显着抑制 PAM 中 PRRSV 的复制。荧光素酶报告基因实验和 RISC 免疫沉淀试验用于鉴定 ssc-miR-124a 可以以序列特异性方式直接靶向猪 CD163 mRNA 的 3'UTR，并且在过表达 ssc-miR-的 PAM 中 CD163 mRNA 和蛋白质水平降低。 124a。