IMMUNOLOGICAL CROSS-REACTIONS BETWEEN AEROMONAS-SALMONICIDA AND VIBRIO-SALMONICIDA IN ATLANTIC SALMON (SALMO-SALAR L.) AND RABBIT

Immunological cross reactions between Aeromonas salmonicida and three species of Vibrio were evaluated. Each of five groups of Atlantic salm on were injected with one of the following oil-adjuvanted bacterins: A eromonas salmonicida ss. salmonicida, Vibrio salmonicida, Vibrio angui llarum serovar O1 and Vibrio anguillarum serovar O2 or with placebo. I n addition, rabbits were immunised with the same oil-adjuvanted bacter ins of A. salmonicida or V. salmonicida. The levels of specific antibo dies against A. salmonicida antigens were measured in an ELISA, and th e responses were characterised in Western blotting and crossed immunoe lectrophoresis (CIE). Protective immunity against furunculosis in the various groups of Atlantic salmon was measured in a virulent cohabitan t challenge. Atlantic salmon and. rabbit vaccinated against V. salmoni cida produced antibodies that crossreacted with antigen preparations o f A. salmonicida in ELISA, Western blotting and CIE (rabbit only). CIE and Western blotting showed that rabbit anti-V. salmonicida reacted w ith antigens on A. salmonicida other than the homologous antisera. Fis h immunised against V. salmonicida were significantly protected in a c ohabitant A. salmonicida challenge. These cross reactions may explain the superior protection against furunculosis achieved with polyvalent vaccines against furunculosis, vibriosis and cold water vibriosis comp ared to a monovalent A. salmonicida vaccine. (C) 1998 Academic Press L imited.