microRNAs (miRNAs) are known to regulate various immune functions by silencing the target genes in both vertebrates and invertebrates. However, in mud crab Scylla paramamosain, the role of miRNAs during the response to virus invasion remains unclear. To investigate the roles of miRNAs in S. paramamosain during virus infection, the mud crab was challenged with white spot syndrome virus (WSSV) and then subjected to the transcriptional analysis at different conditions. The results of high-throughput sequencing revealed that 940,379 and 1,306,023 high-quality mappable reads were detected in the hemocyte of normal and WSSV-infected mud crabs, respectively. Besides, the total number of 261 unique miRNAs were identified. Among them, 131 miRNAs were specifically expressed in the hemocytes of normal mud crabs, 46 miRNAs were specifically transcribed in those of WSSV-infected individuals, the other 84 miRNAs were expressed in both normal and WSSV-infected individuals. Furthermore, a number of 152 (89 down-regulated and 63 up-regulated) miRNAs were found to be differentially expressed in the WSSV-infected hemocytes, normalized to the controls. The identified miRNAs were subjected to GO analysis and target gene prediction and the results suggested that the differentially regulated miRNAs were mainly correlated with the changes of the immune responses of the hemocytes, including phagocytosis, melanism, and apoptosis as well. Taken together, the results demonstrated that the expressed miRNAs during the virus infection were mainly involved in the regulation of immunological pathways in mud crabs. Our findings not only enrich the understanding of the functions of miRNAs in the innate immune system but also provide some novel potential targets for the prevention of WSSV infection in crustaceans.

已知microRNA（miRNA）通过沉默脊椎动物和无脊椎动物中的靶基因来调节各种免疫功能。然而，在泥蟹Scylla paramamosain中，miRNA在病毒入侵反应中的作用仍不清楚。研究miRNA在副链霉菌中的作用在病毒感染期间，用白斑综合症病毒（WSSV）攻击泥蟹，然后在不同条件下进行转录分析。高通量测序的结果表明，在正常和被WSSV感染的泥蟹的血细胞中分别检测到940,379和1,306,023高质量的可作图读物。此外，鉴定出总共261种独特的miRNA。其中，在正常泥蟹的血细胞中特异性表达了131个miRNA，在WSSV感染者中特异性转录了46个miRNA，在正常和WSSV感染者中均表达了其他84个miRNA。此外，发现相对于对照标准化的在WSSV感染的血细胞中差异表达了152种（下调了89种，上调了63种）miRNA。对鉴定出的miRNA进行GO分析和目标基因预测，结果表明，差异调节的miRNA主要与血细胞免疫反应的变化相关，包括吞噬作用，黑素形成和凋亡。综上所述，结果表明在病毒感染期间表达的miRNA主要参与泥蟹的免疫途径的调节。我们的发现不仅丰富了对先天免疫系统中miRNA功能的了解，而且为预防甲壳类动物的WSSV感染提供了一些新的潜在靶标。