Submitted to: Journal of Fish Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/5/2003
Publication Date: 7/1/2003
Citation: ARIAS, C.R., SHOEMAKER, C.A., EVANS, J.J., KLESIUS, P.H. A COMPARATIVE STUDY OF EDWARDSIELLA ICTALURI PARENT (EILO) AND EDWARDSIELLA ICTULARI RIFAMPICIN-MUTANT (RE-33)ISOLATES USING LIPOPOLYSACCHARIDES, OUTER MEMBRANE PROTEINS, FATTY ACIDS, BIOLOG, API 20E, AND GENOMIC ANALYSES. JOURNAL OF FISH DISEASES. 2003. 26, 415-421. Interpretive Summary: The purpose of this study was to better characterize the bacterium Edwardsiella ictaluri that is used in the enteric septicemia of catfish (ESC) vaccine. The commercial vaccine against ESC, AquaVac-ESC®, contains a modified form of this bacterium that protects the fish without causing the disease. We compare this modified strain with the original form of the bacteria. The results of this study showed that one of the main external membrane components (lipopolysaccharides or LPS) had changed in the modified form. We were also able to differentiate between the two forms by using two rapid identification techniques: fatty acids analysis and the commercial system Biolog.
Technical Abstract: The biological properties of Edwardsiella ictaluri RE-33 rifampicin-mutant and its parent strain EILO were analyzed. RE-33 is an avirulent isolate used as a modified live vaccine against Enteric Septicemia of Catfish (ESC). Electrophoretic analysis of lipopolysaccharides (LPS) patterns showed high homology between both isolates. Further characterization of LPS by immunoblotting revealed main differences in LPS composition. RE-33 isolate lacks the high molecular weight bands of the LPS (HMW-LPS). Outer membrane protein (OMP) analysis also showed some immunological differences between RE-33 and EILO parent strain. Only two fingerprinting techniques, fatty acid composition analysis and Biolog phenotypic profiles, were able to discrimate between both isolates.