Disease resistance and immune parameters in Atlantic salmon (Salmo salar L.) with genetically different trypsin isozymes

Genetic variation in responses to vaccination of both specific and non-spec ific immune parameters were observed in individual Atlantic salmon, possess ing different trypsin isozyme patterns in the pyloric caeca and exhibiting different growth rates. Total serum protein concentration and total complem ent haemolytic activity (CH50) were similar after vaccination, while total IgM, lysozyme activity and spontaneous complement haemolytic activity (SH50 ) in the sera were significantly different between salmon with different tr ypsin phenotypes (P<0.05). The values highly correlated with protein concen tration in the sera, such as IgM, CH50 activity and SH50 activity (R-2>0.4, P<0.0001), should be expressed relative to the concentration of serum prot ein as specific production in response to vaccination. A tendency of differ ences in the production of specific antibodies against Aeromonas salmonicid a after 5 months vaccination was observed between the Atlantic salmon with and without the trypsin variant TRP-2*92, although the values were not stat istically different (P=0.12). Whilst it is not known whether vaccinated sal mon of different trypsin phenotypes exhibit differences in disease resistan ce, unvaccinated fish showed similar disease resistance to natural infectio n with furunculosis or by experimental cohabitant challenge with A. salmoni cida ssp. salmonicida. (C) 1999 Academic Press.