DAO 30:77-80 (1997)  -  doi:10.3354/dao030077

Strain differences in non-specific immunity of tilapia Oreochromis niloticus following challenge with Vibrio parahaemolyticus

Balfry SK, Shariff M, Iwama GK

Red and black strains of tilapia Oreochromis niloticus were compared for differences in non-specific immunity. Communally reared, naive fish were challenged with the bacterium Vibrio parahaemolyticus. Serum lysozyme, phagocyte activity and differential leucocyte numbers were examined in pre-challenge and post-challenge fish. The percent cumulative mortality in the 2 strains were not significantly different. There was a significant effect of strain on serum lysozyme activity and phagocyte activity. Phagocyte activity increased significantly following the disease challenge. Lymphocyte numbers decreased significantly in the post-challenge sample, while thrombocytes, neutrophils, and monocytes remained unchanged. This study provides the first report of strain differences in non-specific immunity in tilapia.


Tilapia · Disease resistance · Non-specific immunity · Vibrio parahaemolyticus ยท Lysozyme · Phagocytic activity · Leucocyte counts


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