Newly Emerging Clones of Bordetella pertussis Carrying prn2 and ptxP3 Alleles Implicated in Australian Pertussis Epidemic in 2008–2010

Abstract

Australia is experiencing a prolonged epidemic of pertussis that began in 2008. A total of 194 Bordetella pertussis isolates collected from 2008 through 2010 were typed by single-nucleotide polymorphism (SNP) analysis, by multilocus variable number tandem repeats analysis, and by fim3, prn, and ptxP sequence analyses. Strains with 2 closely related SNP profiles carrying prn2 and ptxP3 from the recently emerged SNP cluster I predominated. The data suggest increasing selection among the B. pertussis population in Australia in favor of strains carrying prn2 and ptxP3 under the pressure of acellular vaccine-induced immunity.

The Bordetella Adenylate Cyclase Repeat-in-Toxin (RTX) Domain Is Immunodominant and Elicits Neutralizing Antibodies

“…While disease incidence has dropped dramatically due to the initiation of widespread vaccination programs using killed bacteria in the 1940s, in recent years rates have rebounded, reaching a 60-year high in the United States in 2012 (1)(2)(3). This trend is especially troubling for unimmunized infants, who are most susceptible to the disease and exhibit the highest rates of morbidity and mortality.…”

“…Exciting approaches in development to enhance vaccinemediated protective immunity include a genetically attenuated B. pertussis for intranasal delivery (6), nanoparticle formulations, including purified antigens and novel adjuvant formulations (7), as well as inclusion of additional highly conserved antigens in the current vaccine (8,9). A strong candidate for inclusion in any of these is the adenylate cyclase toxin (ACT), 2 which aids in immune evasion and is produced by three closely related Bordetella species, including B. pertussis, Bordetella parapertussis, and Bordetella bronchiseptica (10,11).…”

Waning Tdap Effectiveness in Adolescents

“…In 2006, a booster tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis(Tdap) vaccine, was recommended by the Advisory Committee on Immunization Practices for all adolescents. 1 Despite high levels of vaccine coverage, the United States 2 and other countries [3][4][5][6][7] have experienced increased pertussis disease in the years after the switch to DTaP.…”

NSW Annual Immunisation Coverage Report, 2011

“…One important recommendation (according to the Australian Immunisation Handbook) is that new parents, grandparents and adult carers of infants are vaccinated. 6 While vaccine-induced selection pressure on pertussis strains has been suggested as a possible explanation for the significant increases in notifications in Australia in recent years, 7 this is unconfirmed. The greater contribution is likely to have been increased (and more sensitive) testing for pertussis.…”