Chemical and Biological Properties of the Purified O Antigen of Bordetella pertussis

A cell wall fraction obtained by sonic oscillation, yielded a Bordetella pertussis O antigen which possessed the ability to both adsorb O agglutinins and to produce the O agglutinins in animals. It was purified by a phenol water extraction and centrifugation method. Physico‐chemical and biological properties of the O antigen were similar to that of the so‐called endotoxic lipopolysaccharide. It contained 2.6% nitrogen, 1.2–1.5% phosphorus, 9.0–11.0% heptose, 0.3% 2‐keto‐3‐deoxyoctonate (KDO), 13.3–13.4% as total carbohydrate, 16–16.5% hexosamine and 25–32% lipid. Homogeneity of the purified O antigen was confirmed by ultracentrifugation, electronmicrograph and gel‐diffusion tests. It possessed significant pyrogenicity, adjuvant effect on antibody production, and toxicity to animals, but not protective antigenicity.