Transcriptome analysis of Pacific white shrimp (Litopenaeus vannamei) hepatopancreas challenged by Vibrio alginolyticus reveals lipid metabolic disturbance

Vibrio alginolyticus is a devastating bacterial pathogen of Pacific white shrimp (Litopenaeus vannamei), which often causes acute hepatopancreatic necrosis syndrome (AHPNS) and early mortality syndrome (EMS). Elucidation of molecular mechanisms of L. vannamei in responding to infection is essential for controlling the epidemic. In the present study, transcriptomic profiles of L. vannamei hepatopancreas were explored by injecting with PBS or V. alginolyticus. Hepatopancreas morphology of L. vannamei was also assessed. The result reveals that compared with the hepatopancreas of PBS group, the storage cells (R-cell), secretory cells (B-cell) and star shaped polygonal structures of the lumen were disappeared and necrotic after challenged by V. alginolyticus at 24 h. Transcriptome data showed that a total of 314 differential expression genes were induced by V. alginolyticus, with 133 and 181 genes up-and down-regulated, respectively. These genes were mainly associated with lysosome pathway, glycerophospholipid metabolism, drug metabolism-other enzymes, cysteine and methionine metabolism, aminoacyl-tRNA biosynthesis and PPAR signal pathway. Among these pathways, the lysosome pathway, glycerophospholipid metabolism and PPAR signal pathway were both related with lipid metabolism. Therefore, we detected the lipid accumulation in hepatopancreas by Oil Red O staining, TG and CHOL detection and the relative mRNA expression of several lipid metabolism related genes in the hepatopancreas of shrimp after challenge to V. alginolyticus. The present data reveals that lipids from the L. vannamei are nutrient sources for the V. alginolyticus and define the fate of the infection by modulating lipid homeostasis. These findings may have important implication for understanding the L. vannamei and V. alginolyticus interactions, and provide a substantial dataset for further research and may deliver the basis for preventing the bacterial diseases.