[Immunogenic properties of a polyvalent vaccine against colisepticemia in calves]

A polyvalent vaccine was produced against coli septicaemia in calves, using the most commonly encountered serotypes of Escherichia coli as etiologic agents. The effect of the various unspecific factors on the immunogenic properties of the vaccine was followed up through vaccination of guinea pigs, rabbits, and pregnant cows. It was found that best immunogenic effects produced a vaccine that was inactivated by 0.4 per cent formalin and fixed in an oil adjuvant. Guinea pigs that were challenged with 1, 2 and 3 DIM remained 100 per cent alive. Somewhat weaker were the immunogenic properties of vaccinal batches that had such adjuvant as 1 per cent alum or 20 per cent aluminium hydroxide, and weakest proved the immunogenic quality of a vaccine having a 0.01 per cent saponin adjuvant. It was established that the colostrum of cows that were thrice hyperim munized with 5, 10, and 20 cm3 of the vaccine at ten-day intervals contained more specific antibodies than the blood serum. The level of K-agglutinins was shown to exceed considerably that of 0-agglutinins.