1985 Volume 51 Issue 8 Pages 1233-1237
To clarify the protective properties of Edwardsiella tarda polysaccharide reported previously, and to confirm the supposition that the elimination of lipid A from the immunogen can increase the immune protection of the preparation in the eels against experimental challenge with E. tarda EF-1, crude lipopolysaccharide (LPS), purified polysaccharide and whole cell without lipid were injected intramuscularly in the eels.
The highest survival was recorded in eels immunized with crude LPS preparation and good resistance was shown also in the eels immunized with the whole cell without lipid Eels immunized with purified polysaccharide did not show protection after challenge. Chemical analysis showed a high degree of purification for the polysaccharide preparation and perhaps this was the reason for the loss of immunogenicity and effectiveness of the preparation. This may have shown the importance of protein and nucleic acid as haptenes or carriers in the preparations. The results also suggested that the elimination of the lipidic part from the whole cell may be an easy way to obtain an effective vaccine preparation against E. tarda infection.