A new animal model for Bordetella pertussis infection is described. The system utilizes small chambers bounded by 0.22-micron filter membranes. The chambers are inoculated with B. pertussis, sealed, and surgically implanted into the peritoneal cavity of mice. The chamber system allows dynamic interchange of soluble host and bacterial factors, but not cells. We have used this system to study the growth of various clinical isolates and vaccine strains of B. pertussis, including an isogenic virulent/avirulent pair. All virulent strains tested grew well and had remarkably similar growth kinetics. We monitored cellular and humoral host responses, including the response to pertussis toxin. Antitoxin appeared 21-37 days after implantation of the chambers. The model allows us to dissociate the ability of an organism to grow in vivo from other properties (e.g., attachment and toxin production) that may be involved in pathogenesis.