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Recent reemergence of pertussis (whooping cough) in highly vaccinated populations and rapid expansion of Bordetella pertussis strains lacking pertactin (PRN), a common acellular vaccine antigen, have raised the specter of vaccine-driven evolution and potential return of what was once the major killer of children. The discovery that most circulating B. pertussis strains in the United States have acquired new and independent disruptive mutations in PRN is compelling evidence of strong selective pressure. However, the other 4 antigens included in acellular vaccines do not appear to be selected against so rapidly. We consider 3 aspects of PRN that distinguish it from other vaccine antigens, which might, individually or collectively, explain why only this antigen is being precipitously eliminated. An understanding of the increase in PRN-deficient strains should provide useful information for the current search for new protective antigens and provide broader lessons for the design of improved subunit vaccines. [ABSTRACT FROM AUTHOR]

An analysis assessing for associations between pertactin production and both clinical presentation and vaccine history found a significant association between vaccination and pertactin status, suggesting that vaccinated persons have greater susceptibility to pertactin deficient strains compared to pertactin producing strains.Background. A recent increase in Bordetella pertussis without the pertactin protein, an acellular vaccine immunogen, has been reported in the United States. Determining whether pertactin-deficient (PRN–) B. pertussis is evading vaccine-induced immunity or altering the severity of illness is needed.Methods. We retrospectively assessed for associations between pertactin production and both clinical presentation and vaccine history. Cases with isolates collected between May 2011 and February 2013 from 8 states were included. We calculated unadjusted and adjusted odds ratios (ORs) using multivariable logistic regression analysis.Results. Among 753 isolates, 640 (85%) were PRN–. The age distribution differed between cases caused by PRN– B. pertussis and cases caused by B. pertussis producing pertactin (PRN+) (P = .01). The proportion reporting individual pertussis symptoms was similar between the 2 groups, except a higher proportion of PRN+ case-patients reported apnea (P = .005). Twenty-two case-patients were hospitalized; 6% in the PRN+ group compared to 3% in the PRN– group (P = .11). Case-patients having received at least 1 pertussis vaccine dose had a higher odds of having PRN– B. pertussis compared with unvaccinated case-patients (adjusted OR = 2.2; 95% confidence interval [CI], 1.3–4.0). When restricted to case-patients at least 1 year of age and those age-appropriately vaccinated, the adjusted OR increased to 2.7 (95% CI, 1.2–6.1).Conclusions. The significant association between vaccination and isolate pertactin production suggests that the likelihood of having reported disease caused by PRN– compared with PRN+ strains is greater in vaccinated persons. Additional studies are needed to assess whether vaccine effectiveness is diminished against PRN– strains. [ABSTRACT FROM PUBLISHER]

To clarify the characteristics of circulating Bordetella pertussis isolates, we used pulsed-field gel electrophoresis (PFGE) to analyze 5,262 isolates collected in the United States during 2000-2012. We found 199 PFGE profiles; 5 profiles accounted for 72% of isolates. The most common profile, CDC013, accounted for 35%-46% of isolates tested from 2000-2009; however, the proportion of isolates of this profile rapidly decreased in 2010. Profile CDC237, first seen in 2009, increased rapidly and accounted for 29% of 2012 isolates. No location bias was observed among profiles during 2000-2010, but differences were observed among isolates from different states during 2012. Predominant profiles match those observed in recent European PFGE studies. PFGE profile changes are concurrent with other recent molecular changes in B. pertussis and may be contributing to the reemergence of pertussis in the United States. Continued PFGE monitoring is critical for understanding the changing epidemiology of pertussis.