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Responses of Japanese Eels to Oral Challenge with Edwardsiella tarda after Vaccination with Formalin‐Killed Cells or Lipopolysaccharide of the Bacterium
Author(s) -
Gutierrez Miguel A.,
Miyazaki Teruo
Publication year - 1994
Publication title -
journal of aquatic animal health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 52
eISSN - 1548-8667
pISSN - 0899-7659
DOI - 10.1577/1548-8667(1994)006<0110:rojeto>2.3.co;2
Subject(s) - edwardsiella tarda , vaccination , lipopolysaccharide , biology , microbiology and biotechnology , immune system , phagocytosis , immunology , antibody , titer , fish <actinopterygii> , fishery
Vaccination with formalin‐killed cells (FKC) or the lipopolysaccharide (LPS) of Edwardsiella tarda was evaluated for its effectiveness against edwardsiellosis in orally challenged Japanese eels Anguilla japonica . The vaccination procedure was an intramuscular injection of 10 mg FKCs/ 100 g body weight or 1 mg LPS/ 100 g body weight, and a booster of the same type and dose 7 d later. The oral challenge with viable E. tarda was performed with 10 5 ‐10 6 colony‐forming units per fish 21 d after vaccination. At this time, agglutination titers of serum antibody ranged from 1:1,280 to 1:2,560 in the FKC‐vaccinated fish and from 1:3,840 to l:5,120 in the LPS‐vaccinated fish. In the FKC experiment, mortality of vaccinated fish ranged from 60 to 87.5%, whereas the unvaccinated control group had 80–100% mortality; these results indicated slight efficacy of the vaccine. The FKC‐vaccinated fish showed bacterial phagocytosis by macrophages, a process that contributes to a slight decrease in mortality. In the LPS experiment, mortality of vaccinated fish ranged from 40 to 57%, whereas 80–90% mortality occurred in the controls. The LPS‐vaccinated fish displayed demarcation by inflammatory cells against E. tarda in the intestine where E. tarda penetrated, as well as marked bacterial phagocytosis by macrophages, which contributed to a slight increase in survival.