The primary and secondary antibody responses to IROMP antigens in Atlanticsalmon (Salmo salar L) immunised with A(+) and A(-) Aeromonas salmonicida bacterins

The aim of this work was to investigate if the presence of Aeromonas salmon icida A-layer had a suppressive effect on the development of antibodies in Atlantic salmon to outer membrane protein antigens expressed when A. salmon icida is grown under iron-restricting conditions. Atlantic salmon were immu nised with an A-layer positive (A(+)) or A-layer negative (A(-)) A. salmoni cida iron-restricted whole cell bacterin, and were boosted 8 weeks later wi th homologous bacterin, heterologous bacterin, or phosphate buffered saline . Serum antibody titres to iron-restricted outer membrane protein antigens were measured for a period of 8 months. It was found that the presence of A -layer at the time of priming, or the introduction of A-layer 8 weeks post- prime, had no significant effect on the development of antibody responses t o iron-restricted outer membrane protein antigens. In addition, it was foun d that boosting fish when antibody levels are high gave an enhanced antibod y response compared to unboosted fish, and this response was characterised by both an increase in specific antibody titres and an increase in the perc entage of responding fish. (C) 1999 Academic Press.