Porcine reproductive and respiratory syndrome virus (PRRSV) causes tremendous economic losses to the swine industry worldwide. miRNAs are crucial regulators of gene expression and a wide range of complex interactions of miRNAs–mRNAs is possible during virus infection. However, there is no comprehensive integrated study of miRNA and mRNA networks in MARC-145 cells after infection with PRRSV. We analyzed the differential expressions, co-relations, annotations, and putative functions of miRNA and mRNA networks in PRRSV-infected MARC-145 cells. Based on the filtering criterion, 22 differentially expressed miRNAs (DEmiRs) (15 up- and 7 downregulated) were filtered out. miRNA–mRNA interaction networks were constructed. For the 18 selected miRNAs, 390 potential target genes were predicted from the differentially expressed mRNAs (DEmRs). GO and KEGG pathway annotations predicted 34 KEGG pathways, 12 of which are known to be involved in virus infection. Real-time PCR validated the RNA-seq results. Our analysis showed that miR-27a-5p and miR-21-3p downregulate the expression of two of their potential target genes–SPARC, CLIC1, and cofilin-1, COX7A2, respectively. Further experiments proved that miR-21-3p and miR-27a-5p can promote PRRSV replication significantly. It is the first report that these two miRNAs participate in the interaction of host cells with PRRSV. Our results provide insights into the role of miRNAs in response to PRRSV infection, which will aid the research for developing novel therapies against PRRSV.

猪繁殖与呼吸综合症病毒（PRRSV）给全世界的养猪业造成了巨大的经济损失。miRNA是基因表达的关键调节剂，在病毒感染期间，miRNA可能发生多种复杂的相互作用。但是，尚无关于PRRSV感染后MARC-145细胞中miRNA和mRNA网络的全面综合研究。我们分析了PRRSV感染的MARC-145细胞中miRNA和mRNA网络的差异表达，相关性，注释和推定功能。根据过滤标准，滤出了22个差异表达的miRNA（DEmiRs）（上调了15个，下调了7个）。构建了miRNA-mRNA相互作用网络。对于18个选定的miRNA，根据差异表达的mRNA（DEmRs）预测了390个潜在靶基因。GO和KEGG途径注释预测了34条KEGG途径，其中12途径与病毒感染有关。实时PCR验证了RNA-seq结果。我们的分析表明，miR-27a-5p和miR-21-3p分别下调了它们两个潜在靶基因的表达-SPARC，CLIC1和cofilin-1，COX7A2。进一步的实验证明，miR-21-3p和miR-27a-5p可以显着促进PRRSV复制。这是第一个报道，这两个miRNA参与宿主细胞与PRRSV的相互作用。我们的结果提供了有关miRNA在PRRSV感染中的作用的见解，这将有助于研究针对PRRSV的新型疗法。我们的分析表明，miR-27a-5p和miR-21-3p分别下调了它们两个潜在靶基因的表达-SPARC，CLIC1和cofilin-1，COX7A2。进一步的实验证明，miR-21-3p和miR-27a-5p可以显着促进PRRSV复制。这是第一个报道，这两个miRNA参与宿主细胞与PRRSV的相互作用。我们的结果提供了有关miRNA在PRRSV感染中的作用的见解，这将有助于研究针对PRRSV的新型疗法。我们的分析表明，miR-27a-5p和miR-21-3p分别下调了它们两个潜在靶基因的表达-SPARC，CLIC1和cofilin-1，COX7A2。进一步的实验证明，miR-21-3p和miR-27a-5p可以显着促进PRRSV复制。这是第一个报道，这两个miRNA参与宿主细胞与PRRSV的相互作用。我们的结果提供了有关miRNA在PRRSV感染中的作用的见解，这将有助于研究针对PRRSV的新型疗法。这是第一个报道，这两个miRNA参与宿主细胞与PRRSV的相互作用。我们的结果提供了有关miRNA在PRRSV感染中的作用的见解，这将有助于研究针对PRRSV的新型疗法。这是第一个报道，这两个miRNA参与宿主细胞与PRRSV的相互作用。我们的结果提供了有关miRNA在PRRSV感染中的作用的见解，这将有助于研究针对PRRSV的新型疗法。