Vaccination of Full-sib Channel Catfish Families Against Enteric Septicemia of Catfish with an Oral Live Attenuated Edwardsiella ictaluri Vaccine

This study evaluated the efficacy of an oral live attenuated Edwardsiella ictaluri vaccine against enteric septicemia of catfish in 20 full-sib fingerling channel catfish families. The vaccine was delivered orally by feeding fish a diet coated with an attenuated E. ictaluri isolate. Sixty-nine days postvaccination, control and vaccinated fish were challenged with virulent E. ictaluri and mortality was examined for 21d postchallenge. Vaccinated fish had significantly lower mortality than nonvaccinated fish following challenge (P<0.001). Mortality of vaccinated fish was 1.7 +/- 1.4% as opposed to 47.8 +/- 28.7% in nonvaccinated fish. Relative percent survival ranged from 87.7 to 100% with an average of 95.2 +/- 4.0% (+/- SE) among the 20 families of fish. There were significant differences in mortality among families in nonvaccinated fish (P<0.01) while there were no differences among vaccinated families of fish. Results indicate that the live attenuated E. ictaluri vaccine is effective at reducing mortality in channel catfish exposed to virulent E. ictaluri. These data demonstrate that genetic differences among healthy families of channel catfish are not major considerations in developing an effective vaccination program utilizing the oral vaccination platform described in this study.