Dose dependence specific and non-specific immune responses of Indian major carp (L. rohita Ham) to intraperitoneal injection of formalin killed Aeromonas hydrophila whole cell vaccine

Specific and non-specific immune response to different doses of formalin killed whole cell vaccine of Aeromonas hydrophila to Indian major carp (Labeo rohita) was evaluated in laboratory condition. Three different doses (10 ⁵ CFU/ml, 10 ⁷ CFU/ml, 10 ¹⁰ CFU/ml) were administered (0.2 ml/fish) intraperitoneally for 1 month. Among the three doses, 10 ¹⁰ CFU/ml elicited the highest antibody and protective response followed by the doses 10 ⁷ CFU/ml and 10 ⁵ CFU/ml. Upon challenge with the virulent strain of A. hydrophila, the relative percentage of survival was recorded up to 80% at highest dose of 10 ¹⁰ CFU/ml. The non-specific responses, similar to the specific immune responses were also maximum at highest dose of 10 ¹⁰ CFU/ml. Similar to the specific immune responses, the non-specific responses were maximum at highest dose of 10 ¹⁰ CFU/ml. Therefore, dose containing 10 ¹⁰ CFU/ml of formalin killed cells was found to be the most effective dose for vaccination which increased the immunity in Indian major carp (Labeo rohita) to a larger extent.