Acute hepatic injury and metabolic response in hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂) to high-dose Vibrio harveyi infection.

The hybrid groupers (Epinephelus fuscoguttatus female × Epinephelus lanceolatus male) have been seriously harmed by Vibrio harveyi, but the acute damage and the underlying immune defense mechanisms during infection are still unknown. In this study, fish in the treatment group were challenged with 200 µL of V. harveyi suspension (1.01 × 10⁸ CFU/mL) to investigate the mechanisms underlying V. harveyi infection in hybrid grouper by integrating histopathology, biochemistry, and high-resolution transcriptomics. Histopathological analyses revealed that V. harveyi infection induced severe liver apoptosis, as evidenced by TdT-mediated dUTP nick-end labeling assays. Biochemical assays indicated a significant increase in glutamic-pyruvic transaminase (GPT; P < 0.05), while malondialdehyde (MDA) was significantly decreased (P < 0.05). Moreover, transcriptomic profiling revealed significant enrichment in the p53 signaling pathway, alanine, aspartate and glutamate metabolism, and cholesterol metabolism. Quantitative real-time polymerase chain reaction further confirmed the significant upregulation of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and Toll-like receptor 3 (TLR-3). In addition, redundancy analysis revealed the correlations between enzyme activities and differentially expressed genes. Overall, these results demonstrate that V. harveyi infection compromises hepatic health in hybrid grouper by inducing structural damage to the liver, perturbing oxidative stress, and impairing both immune function and metabolic processes.