Dose response of attenuated Bordetella pertussis BPZE1-induced protection in mice.

Despite the availability of efficacious vaccines, the incidence of whooping cough is still high in many countries and is even increasing in countries with high vaccine coverage. Most severe and life-threatening pertussis cases occur in infants who are too young to be sufficiently protected by current vaccine regimens. As a potential solution to this problem, we have developed an attenuated live Bordetella pertussis vaccine strain, named BPZE1. Here, we show that after a single administration, BPZE1 induces dose-dependent protection against challenge with virulent B. pertussis in low-dose and in high-dose intranasal mouse lung colonization models. In addition, we observed BPZE1 dose-dependent antibody titers to B. pertussis antigens, as well as cell-mediated immunity, evidenced by the amounts of gamma interferon (IFN-gamma) released from spleen cells upon stimulation with B. pertussis antigens. These two parameters may perhaps be used as readouts in clinical trials in humans that are currently being planned.