The Comparison of the Duration of Immunity Induced by Pertussis Vaccines and Infection in a Baboon Model

Abstract

Abstract Whooping cough is a highly contagious, acute respiratory illness caused by the Gram-negative bacteria, Bordetella pertussis. Disease is often mild in older children and adults but can be severe or fatal in young children and infants. It is endemic worldwide and a major cause of vaccine-preventable deaths despite high vaccine coverage rate. A steady increase in the number of reported pertussis cases has been evident over the last 20 years. The apparent correlation of this resurgence and the replacement of whole-cell (wP) vaccines with acellular (aP) vaccines suggests the current aP vaccines may not control pertussis as well as the wP vaccines they replaced. Some evidence indicates the aP vaccines may induce protection with shorter duration of immunity relative to wP vaccines. There is increased interest in developing next-generation vaccines that induce longer lasting protection. However, immunological correlates predicting durable and protective immunity remain unknown. Studying duration of immunity in a human population is problematic due to potential asymptomatic exposures and the difficulty in sample accessibility. In an ongoing, long-term study, using a baboon model we are comparing the duration of immunity and immunological correlates of protection in a controlled population comparing aP, wP vaccines and natural infection. Extensive sampling was undertaken around the vaccinations to characterize the vaccine-mediated immune responses. Animals enrolled in the study will be followed for years with sampling twice yearly. With strict control of Bordetella exposure, the data generated from the study will provide a clearer understanding and a basis of comparison for the duration of aP, wP, and infection-induced immunity.