The Reputed Antigenic Relationship between Organisms of the Brucella Group on the One Hand, and of the Pasteurella, Pfeifferella and Proteus Groups on the Other

Abstract

1. Provided that due precautions are taken to ascertain the normal level of agglutinins in a given host, and that antigenically smooth strains are used, there is every reason to believe that the occurrence of agglutinins in a titre above the normal range of variation is due to infection—latent, active or past—with the specific organism in question, or in a few instances with an organism, usually of the same genus, sharing a similar antigen.2. This conclusion may have to be modified for the occurrence of agglutinins to Proteus OX19 in human typhus sera, since the exact relationship of this organism to Rickettsia prowazeki is still doubtful. If, however, future work shows the truth of Felix's (1933) contention that serological types of Proteus X correspond to serological types of typhus virus (Rickettsia), even this apparent exception will fall within the general rule.3. The examination of sixty-four horse and fifty-three cattle sera, and the performance of numerous cross-agglutination and cross-absorption experiments with rabbit and horse antisera, lend no support to the suggestion made by certain workers of the existence of an antigenic relationship between Brucella strains on the one hand, and strains of Pfeifferella, Pasteurella and Proteus X on the other.