ANTIBODY SPECIFICITIES OF POLYCLONAL RABBIT AND RAINBOW-TROUT ANTISERA AGAINST VIBRIO-ORDALII AND SEROTYPE-0 2 STRAINS OF VIBRIO-ANGUILLARUM/

Polyclonal rabbit antisera raised against Vibrio ordalii and serotype 02 strains of Vibrio anguillarum showed extensive cross-reactivity wit h lipopolysaccharide from these bacterial pathogens of fish when teste d in western immunoblot analysis. Results with absorbed polyclonal ant isera indicated that lipopolysaccharide molecules from these strains h ad both common and strain-specific antigenic determinants, which allow ed the antisera to be used to differentiate between V. ordalii and ser otype O2 strains of V. anguillarum. Unlike rabbits, the immune respons e in rainbow trout to serotype 02 common antigenic epitopes was depend ent on the source of the immunizing lipopolysaccharide antigens. Serum from fish immunized with V. ordalii antigens reacted more extensively with serotype 02 common antigens. In contrast, fish anti-V. anguillar um 02 serum did not interact with O antigens from the V. ordalii strai ns. Lipopolysaccharide from V. anguillarum serotype 02 and 02a strains showed identical antibody binding properties when interacted with rab bit or fish antiserum to either V. anguillarum 02 or V. ordalii. Lipop olysaccharide from V. anguillarum 02b strains did not interact with th e tested rabbit or fish polyclonal sera. The results from this study s uggest that fish and rabbits recognise different antigenic determinant s in lipopolysaccharide from V. ordalii and serotpye 02 V. anguillarum strains; that V. ordalli and serotype 02 strains of V. anguillarum sh ould be regarded as distinct serotype 02 subgroups based on the strain -specific antigenic determinants; and finally that the serological cla ssification of V. anguillarum serotype 02b strains should be reexamine d.