Genetic variations in non-specific immune response to experimentally induced infection with Aeromonas hydrophilia in strains of the giant African clariid catfish; Heterobranchus bidorsalis

Non-specific immune response in three strains of Heterobranchus bidorsalis challenged with the bacterium Aeromonas hydrophilia was evaluated. The study was undertaken in three strains of H. bidorsalis from different ecological zones in Nigeria and the percentage cumulative mortality was lowest and significantly different (P<0.05) only in the Dadinkowa strain. There were significant disease and strains effects on both the serum lysozyme activity and leukocytes respiratory burst activity which increased in all the challenged group of fishes. The neutrophils numbers also increased while the lymphocytes decreased and these were also significant in the three strains except in the number of monocytes which wasn’t significantly different (P>0.05). The possibility for genetic improvement for diseases resistance in H. bidorsalis through selection of strains with improved non-specific defense mechanism is highlighted.Keywords: H. bidorsalis, strain, non-specific immunity, selectio