Extracted protective antigen of Bordetella pertussis. I. Preparation and properties of the solubilized surface of components.

Bordetella pertussis microorganisms were treated with several extracting agents followed by ultracentrifugation to remove particulate matter. Analysis of the resulting supernatants by SDS gel electrophoresis showed one major component after simple salt extraction, and much more complex, although consistent pattern following detergent treatment. The yield of the solubilized protein in detergent extracts exceeded by far the values recorded for salt extracts. In order to prevent irreversible precipitation of the solubilized proteins upon removal of the denaturing agent, a novel procedure was developed. After extraction with urea-salt, the solubilized material was absorbed on a mineral carrier prior to the separation of the denaturing agent. The resulting absorbed vaccine was highly potent in the mouse-protection test, whereas the toxic reactions, elicited upon injection into experimental animals, were reduced in the comparison to the starting material. This diminished reactogenic potential was accompanied by the partial loss of the leukocytosis-promiting factor, whose activity was greatly diminished by urea-salt at alkaline pH-values. The procedure described may be applied to large-scale processing of Bordetella persussis microorganisms. Clinical trials now in progress should confirm or rebut the thesis that increased tolerability of the product, inferred from animal experiments, is reflected by fewer adverse reactions in humans. In the former case, the detergent extract vaccine may constitute a realistic alternative to conventional whole-cell vaccines against whooping-cough.