Virulence Factors Variation Among Bordetella Pertussis Isolates in Iran

Pertussis is still endemic and the recently resurgence of the disease caused by Bordetella pertussis has been shown in many countries. The polymorphism of the virulence genes of B. pertussis and lack of any information about the allelic variation between the Iranian isolates promotes us to analysis of the genes encoded virulence factors including ptxS1, prn, fim3 and cya to understand the differences between circulating strains and vaccine strains. PCR and DNA sequencing of the genes was performed on 31 strains collected from patients in Iran from 2008-2010 after biochemical detection of the isolates. Sequencing results of prn, ptxS1, fim3 and cya genes indicated only one allele of the genes among the isolates including ptxS1A, prn2, fim3B and cyaA2, respectively. The alleles of the studied genes were different from vaccine strains (ptxS1E and B, prn2 and 6, fim3A and cyaA1 and 2) in Iran. Vaccination allows the spread of escape mutants and selects for the strains having different alleles of the genes from vaccine strains. The strains used for vaccine in our country are the same as some other countries in the world and our results of alleles of the studied genes were also the same. It is postulated that similar trend and schedules in vaccination strategies and similar coverage of vaccination and the same vaccines may lead to similar results from variation in the virulence factors involving in the immune response and variation is not related to geographic era.