Genetic and antigenic analysis of Bordetella pertussis isolates recovered from clinical cases in Ontario, Canada, before and after the introduction of the acellular pertussis vaccine.

Sixty-eight Bordetella pertussis isolates (obtained between 1994 and 2004 from the province of Ontario in Canada) were compared by the following phenotypic and genetic analyses: serotyping; pulsed-field gel electrophoresis; and partial DNA sequence analysis of their pertactin, pertussis toxin, and fimbriae genes. Although temporal genetic variations were observed among the isolates, which is consistent with the current view that B. pertussis evolves over time, no specific antigenic or genetic type was detected in 48 isolates collected shortly after the introduction of the acellular pertussis vaccine. Further surveillance with clinical data and isolates collected periodically will be required to ensure that any genetic divergence that could affect vaccine efficacy will not be occurring.