Role of chymotrypsin-like serine proteinase in white spot syndrome virus infection in Fenneropenaeus chinensis

White spot syndrome virus (WSSV) caused a great economic loss in shrimp aquaculture. Although great efforts have been undertaken to characterize the virus disease during the last two decades, there are still lack of effective methods to prevent or cure it. In this study, we investigated the transcriptional expression profiles of 18 key immune-related genes in the Chinese shrimp Fenneropenaeus chinensis which was severely infected by WSSV. We found that the expression levels of 6 genes including chymotrypsin-like serine proteinase (CH-SPase), heat shock protein 70 cognate (HSP70), penaeidin (PEN), peroxinectin (PO), proliferating cell nuclear antigen (PCNA) and argonaute (AGO) changed significantly, while the expression of the other 12 genes had no significant changes compared to the control group. Among the 6 screened genes, CH-SPase showed significantly up-regulation, while the other 5 ones were significantly down-regulated. Knockdown of the expression of CH-SPase in WSSV-infected Chinese shrimp reduced the copy number of WSSV and delayed cumulative mortalities, suggesting that CH-SPase is important for WSSV infection. This study will be helpful to control the disease in shrimp caused by WSSV.