Classical swine fever virus (CSFV) is one of the most important viral pathogens leading worldwide threats to pig industry. MicroRNAs (miRNAs) play important roles in regulating virus replication, but whether miRNAs affect CSFV infection is still poorly understood. In previous study, we identified four miRNAs that were down-regulated by CSFV in swine umbilical vein endothelial cells (SUVEC). In this study, miR-140, one of the most potently down-regulated genes was investigated. We found that the miRNA expression was significantly inhibited by CSFV infection. Subsequent studies revealed that miR-140 mimics significantly inhibited CSFV replication, while the inhibition of endogenous miR-140 enhanced CSFV replication. By using bioinformatics prediction, luciferase reporter system, real-time fluorescence quantitative PCR (RT-qPCR) and Western blot assays, we further demonstrated that miR-140 bind to the 3' UTR of Rab25 mRNA to regulate its expression. We also analyzed the expression pattern of Rab25 in SUVECs after CSFV infection. The results showed that CSFV infection induced Rab25 expression. Finally, Rab25 was found to promote CSFV replication. In conclusion, this study demonstrated that CSFV inhibits miR-140 expression and miR-140 inhibits replication by binding to host factor Rab25.

中文翻译：

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MiR-140通过靶向Rab25靶向猪脐静脉内皮细胞来抑制经典猪瘟病毒复制。

古典猪瘟病毒（CSFV）是最重要的病毒病原体之一，对猪业造成了全球性威胁。微小RNA（miRNA）在调节病毒复制中起着重要作用，但是，关于miRNA是否影响CSFV感染仍知之甚少。在先前的研究中，我们鉴定了猪脐静脉内皮细胞（SUVEC）中CSFV下调的四个miRNA。在这项研究中，对miR-140（最有力的下调基因之一）进行了研究。我们发现，miRNA表达被CSFV感染显着抑制。随后的研究表明，miR-140模拟物显着抑制了CSFV复制，而抑制内源性miR-140增强了CSFV复制。通过使用生物信息学预测，萤光素酶报告系统，实时荧光定量PCR（RT-qPCR）和Western印迹检测，我们进一步证明miR-140与Rab25 mRNA的3'UTR结合以调节其表达。我们还分析了CSFV感染后SUVECs中Rab25的表达模式。结果表明，CSFV感染诱导了Rab25表达。最后，发现Rab25促进CSFV复制。总之，这项研究证明CSFV通过与宿主因子Rab25结合抑制miR-140的表达，并且miR-140抑制复制。