ANTIGENIC RELATIONSHIPS AMONG BACTEROIDES SPECIES STUDIED BY ROCKET-LINE IMMUNOELECTROPHORESIS

Antigenic relationships among the 10 Bacteroides species, Porphyromona s gingivalis, Prevotella bivia, and Prevotella intermedia were investi gated by rocket-line immunoelectrophoresis, using antigenic extracts p repared from type strains and antisera to Bacteroides fragilis, Bacter oides distasonis, Bacteroides thetaiotaomicron, Porphyromonas gingival is, and Prevotella intermedia. Among the members of the genus Bacteroi des, B. fragilis, Bacteroides caccae, Bacteroides stercoris, Bacteroid es vulgatus, B. thetaiotaomicron, and Bacteroides ovatus were found to be closely related, and B. distasonis and Bacteroides merdae were the species that were most distantly related to B.fragilis; Bacteroides e ggerthii and Bacteroides uniformis were in an intermediate position. P orphyromonas gingivalis, Prevotella bivia, and Prevotella intermedia s hared very low percentages of common antigens with the Bacteroides spe cies. Detection of enzymic activities in immunoprecipitates allowed us to identify some antigens to enzymes and to study the immunological s imilarities of the enzymes. The malate dehydrogenases of the Bacteroid es species were genus specific, and the glucose-6-phosphate dehydrogen ases of most species exhibited antigenic similarities. The esterases o f B. distasonis and B. thetaiotaomicron appeared to be species specifi c, whereas the esterases and phosphatases of B. fragilis cross-reacted with the esterases and phosphatases of B. stercoris and B. vulgatus, as did the phosphatases of B. distasonis and B. merdae. The phosphatas es of B. eggerthii, B. uniformis, Porphyromonas gingivalis, and Prevot ella intermedia were antigenically similar.