Effect of Whole Cell Vaccination on Major Virulence Factor Expression of Bordetella pertussis Isolates in Iran

Background and Objective: Bordetella pertussis is the causative agent of whooping cough, a highly contagious respiratory disease most severe in infants and young children. Notably, the resurgence of pertussis has recently been associated with the emergence and spread of pertussis toxin promoter (ptxP3) isolates and lacking the production of vaccine virulence factors. In This study, we screened Fha and Prn production from 110 isolates collected during 2005-2018, in Iran with WCV immunization program.Materials and Methods: We selected 110 B. pertussis isolates from Pertussis Reference Laboratory of Pasteur Institute of Iran. Real-time PCR was used to confirm B.pertussis. To evaluate the expression of major virulence factors Pertactin (PRN) and filamentous hemagglutinin (FHA), SDS-PAGE and western-blot were used.Results: The western blot analysis showed that all tested B. pertussis isolates expressed Prn and all but one expressed Fha and one isolate was identified with severely reduced express Fha. We sequenced genomes of these strains and identified differences, compared with genome reference B. pertussis Tohama I.Conclusion: In conclusion, in many countries reporting Prn and Fha-deficiency due to vaccine influence but in Iran it does not look like this. Because, ACV-induced immunity is focused on just a few proteins, creating a stronger selection pressure for strains expressing antigenic variants of these proteins. These results demonstrate that the surveillance of B. pertussis provides a better understanding of the effect of WCV on the evolution of the pathogen deficiency, emphasizes the importance of continued surveillance of other major pertussis virulence factors and help optimize strategies to reduce the incidence of pertussis.