Analysis of Bordetella pertussis pertactin and pertussis toxin types from Queensland, Australia, 1999–2003

In Australia two acellular Bordetella pertussis vaccines have replaced the use of a whole cell vaccine. Both of the licensed acellular vaccines contain the following three components; pertussis toxoid, pertussis filamentous haemagglutinin and the 69 kDa pertactin adhesin. One vaccine also contains pertussis fimbriae 2 and 3. Various researchers have postulated that herd immunity due to high levels of pertussis vaccination might be influencing the makeup of endemic B. pertussis populations by selective pressure for strains possessing variants of these genes, in particular the pertactin gene type. Some publications have suggested that B. pertussis variants may be contributing to a reduced efficacy of the existing vaccines and a concomitant re-emergence of pertussis within vaccinated populations. This study was conducted to survey the pertactin and pertussis toxin subunit 1 types from B. pertussis isolates in Queensland, Australia following the introduction of acellular vaccines.

Pertactin typing showed that 38 isolates possessed the prn1 allele, 3 possessed the prn2 allele and 5 possessed the prn3 allele. All forty-six isolates possessed the pertussis toxin ptxS1A genotype. Amongst the circulating B. pertussis population in Queensland, 82.5% of the recovered clinical isolates therefore possessed the prn1/ptxS1A genotype.