Development and efficacy of autogenous multivalent vaccine to prevent Motile Aeromonas Septicemia (MAS) and Bacillary Necrosis of Pangasius (BNP) in striped catfish (Pangasianodon hypophthalmus).

Abstract

Vaccines are central to disease prevention in farmed fish and help reduce antimicrobial use in aquaculture. Autogenous vaccines represent a practical solution for managing pathogens with high genetic variability, particularly in urgent outbreaks. In this study, 28 bacterial strains were isolated from striped catfish (P. hypophthalmus) suffering from Motile Aeromonas Septicaemia (MAS) and Bacillary Necrosis of Pangasius (BNP). Strains were identified using specific primers, 16S rRNA gene sequencing, and DNA fingerprinting, followed by virulence gene screening and pathogenicity testing. Two strains of Aeromonas VH31, VH74, and two strains of Edwardsiella ictaluri VH83, VH116 were selected to formulate injectable autogenous oil-emulsion vaccines. Experimental trials included four groups of bivalent vaccines (VC-VH31/83, VC-VH31/116, VC-VH74/83, VC-VH74/116), one multivalent vaccine (VC-VHMix), and a PBS control, evaluated over 60 days. The multivalent vaccine conferred the highest relative percent survival (91.7%), while VC-VH31/83 and VC-VH31/116 showed moderate protection (66.7% and 70.8%, respectively). In contrast, VC-VH74/83 and VC-VH74/116 yielded minimal protection (12.5%). Serum IgM antibody analysis showed that the fish had an immune response to Aeromonas and Edwardsiella antigens after 15-30 days of vaccination in the vaccine injection treatments. The concentration of total WBCs, lymphocytes, and granulocytes in the blood of the fish increased and peaked after 45 days. Overall growth performance in the most effective vaccine groups (VC-VHMix, VC-VH31/83, VC-VH31/116) was not significantly affected compared to the control. These results demonstrate that autogenous vaccines are a promising approach to control dual infections of MAS and BNP in striped catfish and highlight their potential role in sustainable aquaculture disease management.