This experiment suggest that Bile and Bile acid has an antidotal effect for every strain of Rickettsia tsutsugamushi (orientalis), and that immunological hetegenity among strains of Rickettsia orientalis can be differentiated by the serological cross test with the immune state of mice surviving infection as a result of treatment with Bile and Bile acid. Observation was made in many mice which were injected with the "Umayado", Ozeki and Shichito strain of Rickettsia tsutsugamushi (orientalis). Material of inoculation as follows; 1, 3, 5% Solution of Bile, and 10(-4)-10(-5.5) Natrium salt of Bile acid mixed with 10(-2), 10(-3) brain emulsion of infected mice by these strains, in same quantity, for 10, 20, 30 minutes at 4 C. 1. 0.2ml of this material (Umayado), in each dencity and time, was inoculated subcutaneously for primary immunization of mice and these mice were challenged intraperitoneally after 65 days inoculated by 0.3ml, 10(-2) Emulsion of three strains as a cross immunization test. Antigenic relationship among three strains were investigated from mortalities of mice after primary infection for 65 days and after challenge for 20 days. 2. One paralled series of observation was made in mice. Employing in subcutaneous infecting dose of 10(-2)-10(-3) dilution of these strain mixed with 1-5% Bile for 20-30 minutes, greater part of 150 mice survived and in every case antidotal effect of Bile was demonstrated distinctly. The same result was noticed in Ozeki and Shichito strain. 3. Cross immunization test was observed in mice survived after primary inoculation of Umayado and Ozeki strain treated with Bile same qualified.
Greater part of immunized mice remained resistent to reinfection, by the challenge of the strain of Umayado and Ozeki, but in case of Shichito strain, mortality of survived mice after primary infection was higher than other homologous strains. The greater part of mice by primary inoculation with Shichito strain treated with Bile succumbed to reinfection with Umayado and Ozeki strain. These result of cross immunization test suggest that Umayado strain is similar to Ozeki strain in its antigenic structure. 4. It was difficult to examin about the antidotal effect of Natrium cholate and Natrium desoxycholate for Rickettsia orientalis, because these bile acids were toxic for maus, but immunogenicity of R. orientalis treated with Bile acid seemed to be maintained. In short, it is recognized that Bile has not influence on the immunogenicity but a antidotal effect for R. orientalis. This fact suggest that Comparsion of heterogenity among strains of tsutsugamushi disease are investigated with surer confidence than the immunological test hitherto in common use.