Dynamic distribution of mud crab reovirus (MCRV) and haemolymph transcriptome analysis in experimentally infected mud crab (Scylla paramamosain)

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As a commercially valuable crustacean species in mariculture systems, mud crab ( Scylla paramamosain) has a broad geographical distribution across intertidal zones of the Indo-Pacific region, particularly in Southeast Asian. Mud crab reovirus (MCRV) is a double-stranded RNA virus that causes severe disease in cultured mud crabs, leading to serious economic loss for the mud crab aquaculture. In this study, the dynamic distribution and tropism of MCRV in the tissues of S. paramamosain was investigated, also, transcriptome differences of hemocytes between MCRV-infected and control group were compared. Results demonstrated a significant reduction of the cumulative survival rate in the MCRV-infected group compared to the PBS-injected control group at 96 h post-infection (45.83 % vs.100.00 %), with the highest mortality at the initial 24 h post-infection (hpi). A remarkable increase of MCRV could be detected in hepatopancreas, hemocytes, muscles and gills, with hemocytes exhibited the highest viral load from 6 to 96 hpi. Transcriptome analysis of hemocytes identified 196 differentially expressed genes (147 up-regulated and 49 down-regulated genes), including eukaryotic elongation factor 1-alpha (EEF1A), interferon gamma inducible protein 30 (IFI30) and myoferlin (MYOF). GO enriched pathways linked to plasma membrane and neural regulation were identified, KEGG pathway analysis indicated that differentially expressed genes were obviously enriched in the pathways related to vascular smooth muscle contraction, which contribute to the molecular mechanisms underlying the response to MCRV infection. These results will be helpful to future research on the pathogenicity of MCRV and the development of effective control strategies against this pathogen in S. paramamosain . ● The dynamic distribution of MCRV in the tissues of Scylla paramamosain was investigated. ● Hemocytes exhibited the highest viral load from 6 to 96 hpi. ● Interferon gamma inducible protein 30 (IFI30) was significantly up-regulated in the hemocytes of infected group. ● Pathways linked to plasma membrane and neural regulation were identified as responsive to MCRV infection.