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Rare Detection of Bordetella pertussis Pertactin-Deficient Strains in Argentina
Abstract:
Pertussis resurgence had been attributed to waning vaccine immunity and Bordetella pertussis adaptation to escape vaccine-induced immunity. Circulating bacteria differ genotypically from strains used in production of pertussis vaccine. Pertactin-deficient strains are highly prevalent in countries that use acellular vaccine (aP), suggesting strong aP-imposed selection of circulating bacteria. To corroborate this hypothesis, systematic studies on pertactin prevalence of infection in countries using whole-cell vaccine are needed. We provide pertussis epidemiologic data and molecular characterization of B. pertussis isolates from Buenos Aires, Argentina, during 2000-2017. This area used primary vaccination with whole-cell vaccine. Since 2002, pertussis case incidences increased at regular 4-year outbreaks; most cases were in infants <1 year of age. Of the B. pertussis isolates analyzed, 90.6% (317/350) contained the ptxP3-ptxA1-prn2-fim3-2 allelic profile. Immunoblotting and sequencing techniques detected only the 2 pertactin-deficient isolates. The low prevalence of pertactin-deficient strains in Argentina suggests that loss of pertactin gene expression might be driven by aP vaccine.
Insights
Pertussis (whooping cough) is resurging, possibly due to bacteria adapting to vaccines. Studies in Argentina, using whole-cell vaccines, found few pertactin-deficient Bordetella pertussis strains, suggesting acellular vaccines drive this bacterial change.
Area of Science:
- * Microbiology and Immunology
- * Epidemiology and Public Health
Background:
- * Resurgence of pertussis (whooping cough) is linked to waning immunity and bacterial adaptation.
- * Genotypic differences exist between circulating Bordetella pertussis and vaccine strains.
- * Pertactin-deficient strains are common in countries using acellular pertussis (aP) vaccines, indicating selection pressure.
Purpose of the Study:
- * To investigate pertactin prevalence in Bordetella pertussis isolates from a region using whole-cell pertussis (wP) vaccine.
- * To analyze pertussis epidemiology and molecular characteristics in Buenos Aires, Argentina (2000-2017).
Main Methods:
- * Epidemiologic data collection for pertussis cases.
- * Molecular characterization of Bordetella pertussis isolates.
- * Genotyping and sequencing to identify allelic profiles and pertactin deficiency using immunoblotting.
Main Results:
- * Pertussis incidence increased with regular 4-year outbreaks, primarily affecting infants under 1 year.
- * 90.6% of analyzed Bordetella pertussis isolates (317/350) possessed the ptxP3-ptxA1-prn2-fim3-2 allelic profile.
- * Only 2 pertactin-deficient isolates were detected, indicating very low prevalence.
Conclusions:
- * The low prevalence of pertactin-deficient Bordetella pertussis in Argentina suggests this bacterial trait is not driven by wP vaccination.
- * The findings support the hypothesis that acellular pertussis (aP) vaccines impose selection pressure favoring pertactin-deficient strains.
