Cross‐protection after immunization of Atlantic salmon, Salmo salar L., against different strains of Vibrio salmonicida

Abstract. Atlantic salmon were immunized with one or other of two bacterins made from different strains of Vibrio salmonicida. The two strains differed both in geographic origin and plasmid profile. One of the strains had given rise to disease outbreaks in salmon and also in cod which were kept in net-pens. However, by using a virulent challenge, it appeared that salmon, immunized with any of the two strains, were also protected against infection with the other. This result indicates that the two strains are serologically similar.