Differential expression of microRNAs in mud crab Scylla paramamosain in response to white spot syndrome virus (WSSV) infection.

Till date numerous microRNAs (miRNAs) have been discovered from various organisms, including fish, shellfish and crustaceans. The miRNAs are known to regulate immune functions in crustaceans, but little is known about the role of miRNAs against viral infection in crab. We performed small RNA sequencing to characterize the differentially expressed miRNAs in WSSV infected Scylla paramamosain, in comparison to that in uninfected crab, at 2 h and 12 h post infection. In total, 24 host miRNAs were up-regulated and 25 host miRNAs were down-regulated in response to WSSV infection at 2 h post infection. And 27 host miRNAs were up-regulated and 30 host miRNAs were down-regulated in response to WSSV infection at 12 h post infection. Further, the gene ontology analysis revealed that many signaling pathways were mediated by these miRNAs. The integral component of membrane is the most important biological process and endocytosis pathway is the most important pathway, which indicates that endocytosis is very important for WSSV infection. This study is one important attempt at characterizing crab miRNAs that response to WSSV infection, and will help unravel the miRNA pathways involved in antiviral immunity of crab.