Non-specific immune responses in families of Atlantic salmon, Salmo salar, exhibiting differential resistance to furunculosis

A variety of non-specific humoral and cellular immune-parameters were investigated in five families of farmed Atlantic salmon, Salmo salar, known to exhibit differential susceptibilities to furunculosis in the field (fishfarm) situation. Non-specific phagocyte functions, such as respiratory burst activity and migration, were not found to be significantly different between resistant and susceptible families. Both complement and non-α ₂ macroglobulin (α ₂ m)-antiprotease activity were found to be higher in families of salmon resistant to Aeromonas salmonicida, however, these differences were not significant. Nevertheless, significant (P < 0.05) inverse correlations between both non-specific humoral factors and furunculosis mortalities in two independent data sets were observed. Based on the above observations, both complement and non-α ₂ m-antiprotease activities appear to play a role in resistance against A. salmonicida.