Bacteriological studces on the interference phenomenon with Bacterium tularense. II. Further studies on effective conditions

Abstract

The results obtained from the interfernce tests in mice, guinea-pigs and rabbits were similar to each other, with the evidence that each of the animals was protected against the challenge with more than lethal doses of Bacterium tularense, when they were injected with avirulent or inactivated strains of the organisms one or three days before the challenge. Such early protection occurred prior to the production in animal body of agglutininis and protective antibodies and according to Kitamura et al., the histological pictures were principally the same with those observed in the case of interference phenomenon with ectromelia virus. Furtheremore, Kitamura et al., on the bases of their histopathological findings, proposed that the interference phenomenon was different from the immune phenomenon and it manifested itself as the form of weakened infection. This findings seemed to be harmonious with our findings obtained by observing the change in number of the challenge organisms in the bodies of immunized, interfered and control animals. In immunized animals the challenge organisms disappeared with the lapse of time after challenge and all the animals could survive the challenge. The interfered animals held the challenge organisms for a considerable longer time as compared with immunized animals and were alive for a longer time than the control some of them surviving the challenge. In control animals, the challenge organisms multiplied in their body representing a linear growth curve and killed all the animals by the same dose as was used in the case of immunized and interfered animals.In the successful demonstration of the interference phenomenon, there was a certain quantitative relationship between interfering agent and challenge agent and that the subcutaneous injection of both the agents was found to be best suited for this purpose. This interference phenomenon is non-specific phenomenon and interfering organisms were not influenced by physical and chemical treatments.