Evaluation of pH Inactivated Vaccine for Aeromonas hydrophila Infection in the Nile Tilapia (Oreochromis niloticus L.)

The study investigated the efficacy of a pH inactivated vaccine against Aeromonas hydrophila in the juvenile Nile tilapia (Oreochromis niloticus L.). The inactivated vaccine was developed by treating the bacterial suspension with sodium hydroxide to raise the pH to 10.0, followed by readjustment to neutral pH, and finally formaldehyde treatment. Vaccination was administered via intraperitoneal injection, and fish were subsequently challenged with live A. hydrophila to assess the vaccine's protective efficacy. Clinical observations revealed no mortality during the acclimatization phase, however, signs of infection emerged in non-vaccinated group after bacterial exposure. The computed 100% relative percentage survival (RPS) in the vaccinated and challenged group underscores the vaccine's effectiveness. Thus, the study concludes that the pH inactivated vaccine provides significant protection against A. hydrophila, presenting a viable strategy for enhancing disease resistance in aquaculture settings.