Development and Characterization of a Novel Live Attenuated Vaccine Against Enteric Septicemia of Catfish.

ABSTRACT: Edwardsiella ictaluri is a Gram-negative intracellular pathogen causing enteric septicemia of channel catfish (ESC). Type six secretion system (T6SS) is a sophisticated nanomachine that delivers effector proteins into eukaryotic host cells as well as other bacteria. In the current work, we in-frame deleted the E. ictalurievpB gene located in the T6SS operon by allelic exchange. The safety and efficacy of Ei?evpB as well as Aquavac-ESC, a commercial vaccine manufactured by Intervet/Merck Animal Health, were evaluated in channel catfish (Ictalurus punctatus) fingerlings and fry by immersion exposure. Our results showed that the Ei?evpB strain was avirulent and fully protective in catfish fingerlings. The Ei?evpB strain was also safe in catfish fry, and immersion vaccination with Ei?evpB at doses 106 and 107 CFU/ml in water resulted in 34.24 and 80.34% survival after wild-type immersion challenge compared to sham-vaccinated fry (1.79% survival). Catfish fry vaccinated with Ei?evpB at doses 106, 107, and 108 CFU/ml in water exhibited dose-dependent protection. When compared with Aquavac-ESC, Ei?evpB provided significantly higher protection in catfish fingerlings and fry (p < 0.05). Results indicate that the Ei?evpB strain is safe and can be used to protect catfish fingerlings and fry against E. ictaluri.

SUBMITTER: Abdelhamed H 

PROVIDER: S-EPMC6090022 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature