CIAO3 and infection: Using the murine intranasal challenge model, it was shown that immunisation of mice prior to infection with PRN-deficient isolates with wP and aP vaccines lead to an early clearance of bacteria from the respiratory tract of mice as compared to the non-vaccinated animals, but the antigen-specific whole-cell vaccine (wP-exp) was characterised by the best efficacy and the rate of elimination of B. pertussis strains.