Effectiveness of the Edwardsiella ictaluri whole-cell vaccine in controlling enteric septicemia of catfish disease in striped catfish (Pangasianodon hypophthalmus)

Abstract

In the pangasianodon aquaculture industry at Indonesia, vaccination is considered a backup plan for treating the enteric septicemia of catfish (ESC) diseases. The varied phenotypic and genotypic features of Edwardsiella ictaluri isolates from different aquaculture locations in Indonesia can be used to discover potential vaccine formulations that offer the highest protection against ESC infection. The aim of this work is to establish the best vaccine formulation to prevent ESC infection and to evaluate the synergy and efficacy of multiple antigens in generating immunity in striped catfish. The striped catfish were given 0.1 mL fish⁻¹ of the monovalent, bivalent, and polyvalent-inactivated E. ictaluri bacterin vaccinations intraperitoneally. The assessment of phagocytic activity, lysozyme activity, respiratory burst using the nitro blue tetrazolium (NBT) assay, differential leukocyte count, relative percent survival (RPS), and survival rate (SR) were among the parameters used to evaluate the success of the vaccination. E. ictaluri vaccine preparations from monovalent, bivalent, and polyvalent are inactivated with 0.3% formalin. The monovalent, bivalent, and polyvalent vaccines of E. ictaluri were found to enhance both specific and non-specific immune responses, including increased antibody titers, phagocytic activity, lysozyme production, respiratory burst, and lymphocyte count compared to the control group after 21 days of immune induction and post-challenge test. Our findings indicated that the E. ictaluri polyvalent-inactivated vaccine, which is administered via injection and contains 0.3% formalin, has a greater potential to provide protection than the monovalent and bivalent vaccines. The polyvalent E. ictaluri vaccines were made from the PJbH, P, and PBm1G antigens. Compared to the monovalent, bivalent vaccines, and control, the polyvalent E. ictaluri vaccine, at a dosage of 10¹⁰ CFU fish⁻¹, offered the highest protection significant against multiple E. ictaluri infections, with an RPS value of 61.02%. It could also elicit both specific and non-specific immune responses.