Dissociation of Rickettsia and Proteus X 19 Antibodies in Experimental Typhus Infections

In our studies 1 on the immune response of individuals vaccinated against typhus Rickettsiæ it was found that while the majority of the sera of these persons presented both rickettsial as well as Proteus X₁₉ agglutinins, a number of them had either only one or the other. Furthermore, it has been found that the Proteus X₁₉ antibodies tended to persist longer than the other. As it is difficult to study individuals repeatedly for their antibody content, and in order to find out if similar absence of correlation between the 2 antibodies is also seen in cases of actual disease, this was studied in experimental infection in animals. It has been shown 2 that Myospalax fontanieri differed from guinea pigs in giving, in addition to rickettsial antibodies, high Proteus X₁₉ agglutinins in their serum. These animals have, therefore, been utilized in the present study, and the results herewith are communicated.

Rodents (Myospalax fontanieri), which are susceptible to experimental typhus infection, have been employed. It has been found that serum from normal animals does not give a positive Weil-Felix reaction or rickettsial agglutination. The animals were infected by inoculation of brain emulsion of infected guinea pigs. At different times after the onset of fever, blood was taken by cardiac puncture, and sera examined for Proteus X₁₉ and rickettsial agglutination. It was possible to bleed some animals as many as 5 to 6 times, but in the majority of cases only one bleeding was possible. Altogether 34 samples of blood were obtained from 19 animals at different times. The technic for agglutination tests has been previously described. 1 The agglutinin response of a representative animal is presented in Fig. 1 and the combined results of the experiment are summarized in Table I.

It can be seen from Fig. 1 and the table that while rickettsial agglutinin tended to appear and disappear early, the Weil-Felix reaction in the majority of the animals did not appear until after the first week, and then, except for one animal, persisted long after the fever had subsided. This seems to be in general agreement with the serological results obtained in individuals following typhus vaccination.