Heterologous prime-boost immunization with live attenuated B. pertussis BPZE1 followed by acellular pertussis vaccine in mice.

ABSTRACT

Pertussis is a severe and life-threatening infectious disease. Two successive generations of vaccines have strongly reduced its incidence over the last 70 years. However, despite excellent global vaccine coverage, it is still not under control and constitutes today the most frequent vaccine-preventable childhood disease. New vaccination approaches are therefore needed. Here, we provide preclinical proof of concept for a heterologous prime-boost strategy, using the live attenuated Bordetella pertussis vaccine candidate BPZE1 to prime infant and neonatal mice intranasally and a currently available acellular pertussis vaccine (aPV) as a booster. Intranasal vaccination with BPZE1 provided strong protection against challenge in neonatal mice, which could be boosted with a single dose of aPV. Furthermore, BPZE1 priming induced a strong Th1/Th17 response, which was maintained after repeated aPV administrations, in contrast to non-primed mice, in which aPV administrations resulted in Th2 skewing. In addition to T cell responses, intranasal administration of BPZE1 to infant or neonatal mice also primed antibody responses to B. pertussis antigens, with a strong preference of the IgG2a over the IgG1 isotypes, which was not seen in non-primed animals. Finally, neonatal BPZE1 priming strongly enhanced aPV-induced protection against B. pertussis challenge. These results lend support for a heterologous prime-boost strategy to control pertussis by using BPZE1 early in life and considering the current aPV administrations as booster vaccinations, thereby bridging the gap from birth to the first aPV immunizations and avoiding aPV-mediated Th2 skewing. A first-in-man clinical trial on BPZE1 has recently been successfully completed, which provides hope that these findings may be translated into human applications in the future.