Development of Gamma Irradiation Vaccine against Mannheimia haemolytica: A Preliminary Study

The study aimed to use the several advantages of nuclear techniques for developing irradiation vaccine against Mannheimia haemolytica using different gamma radiation doses for vaccines preparation and different inoculation doses of irradiation vaccine. The M. haemolytica was exposed to different doses of gamma radiation. The dose rate was considered the optimum irradiating dose that was Lethal to M. haemolytica cells and selected for optimal gamma irradiation vaccine. Experimental animals were divided into four groups. The experimental groups injected twice with three weeks interval for tested vaccines. The first group (G1) inoculated with 4×109 bacterial cells/dose from optimum irradiation vaccine. The second group (G2) inoculated with 2×109 bacterial cells/dose from optimum irradiation vaccine. The third group (G3) inoculated with 4×109 bacterial cells/dose from high irradiation vaccine. The fourth group (C) injected (S/C) with 2 mL sterile PBS and was kept as a control group. Vaccination challenge with wild M. haemolytica life organism (0.5 mL of 3.6×1010 mLG1) was two doses for all experimental animals. ELISA was used to evaluate the efficiency of vaccines. The antibodies production are evaluated using Optical Density (OD) value as an indication of the efficiency of vaccine against M. haemolytica. The results revealed that after the second vaccination dose, the OD value of G2 showed a significant difference compared to G1 and G3 groups and it was non-significant between G1 and G3 groups. Comparative analysis of control and the different doses of gamma irradiation vaccines showed that after the second vaccination dose, the mean of OD value of the G2 was a significant different while it was non-significant in the G1and G3 compared to the control group. After vaccination challenge, the mean of OD value of G2 was with high significant different compared to all of vaccinated and control groups.