As shown in Fig. 5C, intraperitoneal immunization with equimolar amounts (31.8 pmol/dose) of either of the recombinant Prn protein variants and with either of its Prn-RTX908 fusions (c.f. Fig. 4A), conferred a high level of protection of mouse lungs against infection by 1 × 105 CFU of B. pertussis Tohama I bacteria applied intranasally in 50 μL of suspension, hence in the B. pertussis mouse lung clearance model that predicts the clinical efficacy of licensed pertussis vaccines (49). Here, CIAO3 is linked to infection.