Infection induces long-lasting protection against pertussis. Similar to natural infection, intranasal BPZE1 (live attenuated B. pertussis) induces both mucosal and systemic immune responses, with the potential for more effective and broader immunity compared to current intramuscular injection of purified pertussis antigens such as aPV.
The BPZE1 strain was found to be non-pathogenic in mouse models and caused no pulmonary inflammation, yet it is able to colonize the mouse respiratory tract nearly as long as the virulent parent strain. A single nasal administration of BPZE1 induces full protection against challenge with virulent B. pertussis in mice (Skerry & Mahon, 2011).
BPZE1-induced protection is mediated by both antibodies and CD4+ T cells (Feunou et al., 2010a). Protection against challenge is dose-dependent (Mielcarek et al., 2010) and is directly related to the ability of the vaccine strain to colonize the respiratory tract and to induce both anti-B. pertussis antibodies and IFN-secreting cells.
In pre-clinical mouse studies, BPZE1 induced long-lasting protection (Feunou et al., 2010b; Skerry & Mahon, 2011). For up to at least one year, a single nasal administration of BPZE1 administered to adult or infant mice provided effective protection against nasal challenge with virulent B. pertussis, whereas immunity induced by two administrations of acellular vaccine (aPV) started to wane 6 months after the last immunization. Furthermore, BPZE1 vaccination induced rapid protection, which can be detected as early as a few days after immunization (Debrie et al., in preparation).