Objectives: Resurgence of pertussis has been observed in many countries with long vaccination history. Moreover, in these countries antigenic divergence in pertussis toxin (Ptx) and pertactin (Prn) has been found between Bordetella pertussis vaccine strains and clinical isolates. In  Serbia, incidence of pertussis has been decreasing since the introduction of vaccination in 1957. The aim of this study was to analyze B.pertussis vaccine strains and isolates circulating between 1953 and 2011 in Serbia, before introduction of a cellular vaccine and to compare them with other countries data to study possible effect of the inclusion of “contemporary” strains in the vaccine composition on temporal trends in B.pertussis population.

Methods: Four vaccine strains and 77 isolates collected from 1953 to 2011 were studied. The methods included serotyping of fimbriae (Fim), genotyping of pertactin (prn) and pertussis toxin S1 subunit (ptxA) and PFGE analysis of vaccine strains and isolates.

Results: The Serbian vaccine strains showed differences in ptxA and prn. Shift from ptxA2 to ptxA1 has been observed in isolates since the late of 1960s. Re-appearance of the ptxA2 allele followed an addition of the two strains harboring ptxA1 in the vaccine in 1985. The allele prn1 was predominant among the Serbian isolates. The prn2 allele was only found in one strain isolated in 1984 and five strains isolated after 2000. Serotype Fim2.3 disappeared before 1980 and serotype Fim2 became predominant since then.

Conclusion: The results of this present study indicate that the B. pertussis population in Serbia is different from other vaccinated populations and that this difference may be related to the vaccine used, so it is possible that inclusion of “contemporary” strains in the vaccine composition could have a positive effect on changes in B. pertussis population and low incidence of the disease.

 Key words: Bordetella pertussis, pertussis toxin, pertactin, pertussis