Tissue persistence and vaccine efficacy of tricarboxylic acid cycle and one-carbon metabolism mutant strains of Edwardsiella ictaluri.
Edwardsiella ictaluri causes enteric septicemia in fish. Recently, we reported construction of E. ictaluri mutants with single and double gene deletions in tricarboxylic acid cycle (TCA) and one-carbon (C-1) metabolism. Here, we report the tissue persistence, virulence, and vaccine efficacy of TCA cycle (EiΔsdhC, EiΔfrdA, and EiΔmdh), C-1 metabolism (EiΔgcvP and EiΔglyA), and combination mutants (EiΔfrdAΔsdhC, EiΔgcvPΔsdhC, EiΔmdhΔsdhC, and EiΔgcvPΔglyA) in channel catfish. The tissue persistence study showed that EiΔsdhC, EiΔfrdA, EiΔfrdAΔsdhC, and EiΔgcvPΔsdhC were able to invade catfish and persist until 11 days post-infection. Vaccination of catfish fingerlings with all nine mutants provided significant (P<0.05) protection against subsequent challenge with the virulent parental strain. Vaccinated catfish fingerlings had 100% survival when subsequently challenged by immersion with wild-type E. ictaluri except for EiΔgcvPΔglyA and EiΔgcvP. Mutant EiΔgcvPΔsdhC was found to be very good at protecting catfish fry, as evidenced by 10-fold higher survival compared to non-vaccinated fish.
Department of Basic Sciences, College of Veterinary Medicine Sciences, Mississippi State University, Mississippi State, MS, USA.
Neeti
N
Dahal
Department of Basic Sciences, College of Veterinary Medicine Sciences, Mississippi State University, Mississippi State, MS, USA.
Hossam
H
Abdelhamed
Department of Basic Sciences, College of Veterinary Medicine Sciences, Mississippi State University, Mississippi State, MS, USA. Electronic address: karsi@cvm.msstate.edu.
Attila
A
Karsi
Department of Basic Sciences, College of Veterinary Medicine Sciences, Mississippi State University, Mississippi State, MS, USA. Electronic address: lawrence@cvm.msstate.edu.
Mark L
ML
Lawrence
D000818:Animals; D001428:Bacterial Vaccines / Q000276:immunology*; D002244:Carbon / Q000378:metabolism; D002952:Citric Acid Cycle; D020610:Edwardsiella ictaluri / Q000235:genetics*; D004756:Enterobacteriaceae Infections / Q000517:prevention & control / Q000662:veterinary*; D005393:Fish Diseases / Q000517:prevention & control*; D017353:Gene Deletion; D007059:Ictaluridae / Q000276:immunology
D001428:Bacterial Vaccines; D002244:Carbon
Aquaculture; Channel catfish; Edwardsiella ictaluri; Ictalurus punctatus; Live attenuated vaccine