[Nonspecific immunostimulating activity of Bordetella bronchiseptica bacterin in tests on mice and calves]

Three experimental models were used to verify the effectiveness of immunostimulant preparations of microbial origin. Of the four microbial species, used in the tests with the stimulation of mice against subsequent infection with the virulent strain of Pasteurella multocida, the highest resistance-increasing power was recorded in Bordetella bronchiseptica. There were large differences in stimulation activity between its strains, ranging from those with a low activity up to strain 6229, which increased the LD50 of the infected mice to a level 72 times as high as in the control. The differences in the survival of the mice also varied within the range between immunostimulation and infection, the best effect being obtained when the mice were stimulated 48 h before the infection. No significant difference was recorded between the use of the bacterin of B. bronchiseptica alone or B. bronchiseptica bacterine with oil adjuvant. The immunostimulant activity of B. bronchiseptica was also demonstrated in the model of sublethally irradiated mice in which the preventive administration 24 h before irradiation led to earlier and faster regeneration of the lymphoid tissue: this led to a higher weight of the spleen, to an increase in the number of peripheral leucocytes, and increased activity of chemiluminiscence six days after irradiation. The bacterine of B. bronchiseptica was also used at different concentrations and in combinations with other substances to stimulate two-month-old clinically healthy calves. The most pronounced effect was obtained after the administration of B. bronciseptica bacterine with oil adjuvant and after administration of the same substances together with vitamin A: twenty-four hours after these treatments there was an increased number of peripheral leucocytes and after 2-4 days an increased activity was observed in the MSHP particle phagocytosis test and in the chemiluminiscence test. The activity of lymphocytes in the blastic transformation test was insignificantly increased seven days after stimulation.