Electrophoretic and immunochemical analyses of the lipopolysaccharides from various strains of Aeromonas hydrophila

Lipopolysaccharides isolated from strains of Aeromonas hydrophila, virulent for fish and which autoaggregate during growth in static broth culture, were examined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The lipopolysaccharides contained O-polysaccharide chains of homogeneous chain length. Two of the strains produced a surface protein array, and immunofluorescence and phage-binding showed that a number of these O-polysaccharide chains of homogeneous length traversed the protein array and were exposed on the cell surface. There were three epitopes on the polysaccharide portion of this homogenous-chain-length lipopolysaccharide morphotype. One epitope was species serogroup specific and reactive by immunoblotting. This epitope was not present on the heterogeneous-chain-length O polysaccharides of non-autoaggregating strains of A. hydrophia examined. The second epitope was conformation dependent and cross-reactive with an epitope on the homogenous-chain-length O polysaccharides of Aeromonas salmonicida lipopolysaccharide. The third epitope was recognized by a monoclonal antibody and appeared to involve that region of the A. hydrophila and A. salmonicida lipopolysaccharide molecules which contained the O-polysaccharide-core oligosaccharide glycosidic linkage..