Characterization of the surface antigens of the marine fish pathogens Vibrio anguillarum and Vibrio ordalii.

The technique of immunoblotting was used to identify the surface antigens of the marine vibrios pathogenic for fish, Vibrio anguillarum and Vibrio ordalii. Polyclonal antisera raised in rabbits to strains representing the two most common serotypes causing Vibriosis in fish in North America were used. The results demonstrated that antigenic specificity was conferred by the lipopolysaccharides, with three serotypes being displayed among the strains examined. The lipopolysaccharides of strains chosen as type species for V. anguillarum and V. ordalii displayed antigenic cross-reactivity. The morphological heterogeneity of the Vibrio lipopolysaccharides was also analyzed in silver-stained polyacrylamide gels and by intrinsic 32P-radiolabelling. Two distinct lipopolysaccharide morphologies were exhibited, one with 0 polysaccharide chains of heterogeneous chain length, the other having 0 polysaccharide chains of more uniform chain length but displaying microheterogeneity. These lipopolysaccharide morphologies corresponded to different serogroups. Two minor proteins of apparent molecular weights 49000-51000 present in outer membrane preparations isolated by the sarcosinate extraction procedure were also strong antigens, and common to all strains of V. anguillarum tested and to several strains of V. ordalii. The major outer membrane protein was a weak antigen common to both species.