Sp ICAD contributes to WSSV infection by suppressing apoptosis in mud crab ( Scylla paramamosain )

ICAD is the inhibitor of caspase-activated deoxyribonuclease and has been widely investigated for its apoptotic regulatory function in higher animals, whereas apoptosis is tightly relevant to immune defense. However, the involvement of ICAD during virus infection has not been addressed in invertebrates. In this study, SpICAD identified in mud crab (Scylla paramamosain) was characterized, we found that the expression of SpICAD was upregulated during WSSV (White Spot Syndrome Virus) infection in mud crab, then, the role of SpICAD in immunoregulation was further explored via RNAi approach, the data revealed that SpICAD could inhibit caspase signaling and mitochondrial membrane potential (??m) and thus suppress apoptosis process. Moreover, our results showed that virus infection could activate SpICAD to reduce the apoptosis rate of hemocyte, which eventually contribute to WSSV replication in mud crab. The current study therefore provides novel insights into the anti-viral immune response of mud crabs.