To investigate vaccine efficacy against B. pertussis, groups of mice were immunized with DTaP vaccines containing either two (DTaP2; PT and FHA) or three (DTaP3; PT, FHA and Prn) pertussis components, or a DTwP vaccine containing inactivated whole B. pertussis. Unvaccinated mice were used as a control. The gene discussed is CIAO3; the disease is pertussis.