Survival and immune-related gene expression in Litopenaeus vannamei co-infected with WSSV and Vibrio parahaemolyticus

In the present study, survival and immune-related gene expression were investigated in Litopenaeus vannamei co-infected with white spot syndrome virus (WSSV) and Vibrio parahaemolyticus by ingestion and immersion, respectively. The expression of five immune-related genes (translationally controlled tumor protein [TCTP], toll receptor [LvToll], penaeidin4, crustin, and lysozyme) in hemocytes of experimental shrimp was measured by real-time quantitative PCR. Shrimp infected first with V. parahaemolyticus and then with WSSV showed a mortality of 46.66 ± 0.88%. Shrimp infected first with WSSV and then with V. parahaemolyticus showed a mortality of 45.00 ± 1.53%. Shrimp infected with WSSV and V. parahaemolyticus at the same time showed a mortality of 55.00 ± 2.08%. Gene expression of LvToll, crustin, and lysozyme was upregulated whereas gene expression of TCTP and penaeidin4 was downregulated. Under the present experimental conditions and infection routes, V. parahaemolyticus was the main responsible for the mortality of cultured white shrimp. Regarding immune response, significant changes were found in gene expression in hemocytes of L. vannamei during the time-course of a successful immune response to pathogens V. parahaemolyticus and WSSV. Statement of relevance Bacterial and viral co-infection in white shrimp culture.