Immunogenicity and Protective Efficacy of an Acellular Pertussis Vaccine Candidate in in a Murine Model

Abstract

Acellular pertussis vaccines (aPVs) have been developed as an alternative to whole-cell pertussis vaccines (wPVs) because of their similar efficacy but reduced reactogenicity. The aPV contains 3 or more immunogenic components of Bordetella pertussis. We aimed to evaluate the immunogenicity and protective potency of an aPV vaccine produced in our laboratory consisting of pertussis toxin (PT), filamentous hemagglutinin (FHA), and pertactin (PRN) in mice. The aPV components were produced and purified from the supernatant and pellet of the bacterial culture. Two doses of the formulated vaccine, in parallel with two commercial vaccines, were administered intraperitoneally to mice at 3-week intervals. Antibody titers against aPV antigens were measured by enzyme-linked immunosorbent assay (ELISA) after primary and booster vaccinations. To assess the protective efficacy, an intranasal challenge with a live pathogenic B pertussis strain was conducted 2 weeks after the booster vaccination, and bacterial counts (colony-forming units [CFUs]) in the lungs were determined 2 hours and 10 days after the challenge. The results demonstrated a significant increase in antibody titers against all pertussis antigens in the serum of the vaccinated groups compared with the negative control group, following both the primary and booster doses. No significant differences were observed between our formulation and the commercial vaccines. Furthermore, the CFU results after the challenge showed complete eradication of infection 10 days after the challenge in all immunized groups, in contrast to the control group. Our aPV formulation, the first aPV candidate developed in Iran, exhibits immunogenicity and protective efficacy comparable to those of commercial vaccines. Further investigation of human subjects is warranted.