Integrated Transcriptomic and Proteomic Analysis Reveals the Immune Response of Largemouth Bass ( <i>Micropterus salmoides</i> ) to <i>Aeromonas hydrophila</i> Infection

Largemouth bass (Micropterus salmoides) is an economically important freshwater fish species in China that is frequently affected by disease outbreaks caused by Aeromonas hydrophila. This study employed an integrated transcriptomic and proteomic approach to investigate the response of the liver in largemouth bass at 72 h post-infection with A. hydrophila via intraperitoneal injection. We identified differentially expressed genes (DEGs; 2136 upregulated and 200 downregulated) and differentially expressed proteins (DEPs; 1683 upregulated and 1817 downregulated). Functional enrichment analysis indicated that the upregulated DEGs/DEPs were significantly involved in immune and inflammatory responses, encompassing pathways, such as TNF signalling, NF-kappa B signalling, complement and coagulation cascades and B cell receptor signalling, while the downregulated DEGs/DEPs were primarily associated with metabolic processes, especially lipid metabolism. Integrated transcriptomic and proteomic analysis identified 420 correlated DEG/DEP pairs, among which 154 were consistently upregulated and 19 consistently downregulated. The upregulation of eight key immune-related DEG/DEPs, including complement components (C1q, C7b, C1r-A), MYD88 and BCL10, was verified by RT-qPCR. Collectively, these findings provide valuable insights into the molecular basis of immune defence against A. hydrophila in largemouth bass and identify potential immune-related biomarkers that may be useful in the development of effective prevention and control strategies.