CIAO3 and pertussis: 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).