Research Article: Antibacterial properties of rainbow trout (Oncorhynchus mykiss) pro-hepcidin as a new approach against bacterial disease in fish

This study aimed to produce and evaluate the antibacterial activity of recombinant rainbow trout pro-hepcidin (rpro-RtHep). The gene sequence encoding rainbow trout pro-hepcidin was synthesized and cloned into the pET۲۸a+ expression vector. The recombinant vector pET۲۸a+/pro-RtHep was transformed into Escherichia coli BL۲۱ (DE۳) Rosetta for protein expression. The recombinant bacteria were cultured at ۳۷°C and induced with ۰.۵ mM Isopropyl β-D-۱-thiogalactopyranoside (IPTG). The presence of a ۱۰ kDa band on SDS-PAGE confirmed successful peptide expression; subsequently, purification was carried out using affinity chromatography, and the single ۱۰ kDa band was verified by SDS-PAGE. The biological activity of purified rpro-RtHep was evaluated by examining its inhibitory effects on the growth of selected Aeromonas hydrophila, Streptococcus iniae and Yersinia ruckeri. The results showed that rpro-RtHep effectively inhibited the growth of these bacterial species. Additionally, the survival rate of zebrafish (Danio rerio) and with the rpro-RtHep (۲۵ µg g-۱) was assessed and the results revealed that survival rate was significantly higher compared to that of the control group exposed to A. hydrophila. Immune factors, including lysozyme levels, ACH۵۰, total protein, and total immunoglobulin demonstrated significant increases in fish injected with rpro-RtHep compared to the control group (p<۰.۰۵). The study demonstrated that rpro-RtHep protects zebrafish against A. hydrophila infection via regulating of immune factors.

کلیدواژه ها:

Bacterial resistance ، Antibiotic alternative ، Hepcidin ، Immune factors