Pertactin-Negative and Filamentous Hemagglutinin-Negative Bordetella pertussis, Australia, 2013-2017

Abstract

During the 2008-2012 pertussis epidemic in Australia, pertactin (Prn)-negative Bordetella pertussis emerged. We analyzed 78 isolates from the 2013-2017 epidemic and documented continued expansion of Prn-negative ptxP3 B. pertussis strains. We also detected a filamentous hemagglutinin-negative and Prn-negative B. pertussis isolate.

Keywords: Australia; Bordetella pertussis; Fha-negative; Pertactin; Prn-negative; acellular vaccine; bacteria; filamentous haemagglutinin; fim2; pertussis; ptxP3.

Figure 1

Pertussis trends and temporal changes of allele frequencies of vaccine antigens genes, Australia. A) Pertussis notifications in Australia, 1991–2017. Source: National Notifiable Diseases Surveillance System (http://www9.health.gov.au/cda/source/cda-index.cfm). Incidence is number of cases per 100,000 population. Reporting system was established in 1991. ACV was first introduced in Australia in 1997, and WCV was replaced with ACV in 1999. A large pertussis epidemic occurred during 2008–2012, and another epidemic occurred during 2013–2017. B) Percentage of Bordetella pertussis isolates carrying ptxP3 allele in the 2 epidemic periods. C) Percentage of B. pertussis isolates carrying fim3A and fim3B allele in the 2 epidemic periods. D) Percentage of pertactin-expressing (Prn-positive) and pertactin-deficient (Prn-negative) B. pertussis isolates in the 2 epidemic periods. ACV, acellular vaccine; Prn, pertactin; WCV, whole-cell vaccine.

Figure 2

Phylogenomic relationship of 105 Bordetella pertussis epidemic isolates from Australia. The minimum-evolution tree was constructed using 705 SNPs. The isolates are labeled by name (L numbers), followed by states with color to indicate years of isolates. Shaded areas inside circle indicate ELs (EL1–EL5) and branches with isolates belonging to SP18 and those carrying fim3B and prn3 alleles. Prn-positive isolates and different mechanisms of Prn-negative isolates are marked by circles with different colors. Scale bar represents 3 SNPs. EL, epidemic lineage; NSW, New South Wales; Prn, pertactin; SNP, single-nucleotide polymorphism; SP, SNP profile; WA, Western Australia.