MicroRNA ssc-miR-124a exhibits antiviral activity against porcine reproductive and respiratory syndrome virus via suppression of host genes CD163

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.