What does this research mean for the field?

Four recombinant ESC-NDKL1 vaccine strains expressing two vAh antigens provide significant protection against motile Aeromonas septicemia in channel catfish. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.SUPPORTS_CONSENSUS.

What question did this study set out to answer?

The aim is to develop a recombinant vaccine to protect catfish from motile Aeromonas septicemia caused by virulent A. hydrophila.

February 22, 2026Open Access

Development of a recombinant live attenuated vaccine to protect channel catfish against motile Aeromonas septicemia

Key Points

The aim is to develop a recombinant vaccine to protect catfish from motile Aeromonas septicemia caused by virulent A. hydrophila.
Integrated genes encoding vAh surface antigens into the ESC-NDKL1 chromosome by conjugation.
Created six recombinant ESC-NDKL1 strains expressing one vAh antigen each.
Developed eleven strains expressing two vAh antigens to enhance protection.
Evaluated relative percent survival (RPS) against MAS in all strains.
The six strains expressing one vAh antigen showed RPS ranging from 25.67% to 52.10%.
Four strains expressing two vAh antigens demonstrated significantly improved RPS up to 61.74%.
Statistical significance (p < 0.05) was noted for strains with combined vAh antigens compared to non-recombinant vaccine.

Abstract

Background/objectives Aeromonas hydrophila causes motile Aeromonas septicemia (MAS), which affects farm-raised catfish. Since 2009, outbreaks caused by a clonal genetic group of A. hydrophila (virulent A. hydrophila , or vAh) have caused significant losses of market-size catfish in Alabama and Mississippi. Previously, our group reported that recombinant vAh surface proteins are effective in protecting catfish against MAS. Furthermore, live attenuated Edwardsiella ictaluri vaccine strain ESC-NDKL1 is an efficacious vaccine for enteric septicemia of catfish (ESC). In the current study, we investigated ESC-NDKL1 as a potential vector for expressing vAh antigens. Methods and results Genes encoding vAh surface antigens were integrated into the ESC-NDKL1 chromosome by conjugation and homologous recombination. Six recombinant ESC-NDKL1 strains expressing one vAh antigen (ESC-NDKL1:: atpase , ESC-NDKL1:: fim , ESC-NDKL1:: fimMrfG , ESC-NDKL1:: fimA , ESC-NDKL1 ::tdr , and ESC-NDKL1:: ompA ) showed significant protection against MAS with relative percent survival (RPS) of 52.10%, 25.67%, 39.99%, 38.93%, 47.83%, and 34.07%, respectively. Eleven recombinant ESC-NDKL1 strains expressing two vAh antigens showed significant protection against MAS and improved protection compared to recombinant ESC-NDKL1 strains expressing one vAh antigen. In particular, four recombinant ESC-NDKL1 strains expressing two vAh antigens (ESC-NDKL1:: atpase :: fimMrfG , ESC-NDKL1:: fim :: fimMrfG , ESC-NDKL1:: tdr ::f imMrfG , and ESC-NDKL1:: fim :: ompA) showed significant protection ( p 0.05) compared to non-recombinant ESC-NDKL1 with RPS of 55.72%, 60.18%, 61.74%, and 54.81%, respectively. Conclusion We identified four promising vaccine candidate strains to control MAS in the catfish industry.

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Cite This Study

Gomaa et al. (Thu,) studied this question.

synapsesocial.com/papers/699a9ca1482488d673cd25ec https://doi.org/https://doi.org/10.3389/fbrio.2026.1720345

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