Integrated transcriptomic and metabolomic analysis provides insights into the responses to Vibrio infection in Plectropomus leopardus

Frequent outbreaks of infectious disease in fish aquaculture have led to significant economic losses. The leopard coral grouper (Plectropomus leopardus) is an economically important fish species, but suffering from the vibriosis caused by Vibrio harveyi. Here, we used time-course transcriptomic and metabolomic analysis of the intestine and liver to investigate how the leopard coral grouper responds to the infection of the pathogen V. harveyi. We found that the differentially expressed genes (DEGs) were enriched in lipid synthesis and metabolism, DNA, RNA, and protein synthesis, and peroxisome metabolism pathways. The differential metabolites (DMs) included glycerophospholipids (GPLs), eicosanoids, bile acids (BAs), and amino acids. Further integrated analyses showed that Vibrio infection triggered the arachidonic acid (AA) metabolic process, leading to significant increases in the levels of prostaglandin J2 (PGJ2) and prostaglandin A2 (PGA2), and that this was potentially regulated by the higher expression of key genes in the AA metabolic pathway such as plaat2 and ptgs1. Moreover, the upregulation of the key genes cyp7a1, cyp27a1, and baat enhanced the BA synthesis, resulting in a significant elevation of glycocholic acid (GCA) levels in the enterohepatic circulation. Concurrently, the microbially conjugated BAs in intestine were altered, suggesting a crucial role of various BAs in defending the Vibrio infection. These findings provide novel insights into the molecular responses to Vibrio infection in the leopard coral grouper, serving as a foundation for unraveling the molecular mechanisms underlying the immune responses to Vibrio infection in fish.