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Bordetella pertussis and Bordetella parapertussis: two immunologically distinct species
N Khelef1, B Danve, M J Quentin-Millet
1Unité de Bactériologie Moléculaire et Médicale, Institut Pasteur, Paris, France.
Abstract:
Bordetella pertussis and Bordetella parapertussis are closely related species. Both are responsible for outbreaks of whooping cough in humans and produce similar virulence factors, with the exception of pertussis toxin, specific to B. pertussis. Current pertussis whole-cell vaccine will soon be replaced by acellular vaccines containing major adhesins (filamentous hemagglutinin and pertactin) and major toxin (pertussis toxin). All of these factors are antigens that stimulate a protective immune response in the murine respiratory model and in clinical assays. In the present study, we examined the protective efficacies of these factors, and that of adenylate cyclase-hemolysin, another B. pertussis toxin, against B. parapertussis infection in a murine respiratory model. As expected, pertussis toxin did not protect against B. parapertussis infection, since this bacterium did not express this protein, but the surprising result was that none of the other factors were protective against B. parapertussis infection. Furthermore, B. parapertussis adenylate cyclase-hemolysin, although it protected against B. parapertussis infection, did not protect against B. pertussis infection. Despite a high degree of homology between both B. pertussis and B. parapertussis species, no cross-protection was observed. Our results outline the fact that, as in other gram-negative bacteria, Bordetella surface proteins vary immunologically.
Insights
Despite high genetic similarity, Bordetella pertussis and Bordetella parapertussis virulence factors do not offer cross-protection against whooping cough in mice. This suggests significant immunological variation in Bordetella surface proteins.
Area of Science:
- Microbiology
- Immunology
- Vaccinology
Background:
- Bordetella pertussis and Bordetella parapertussis cause whooping cough and share virulence factors, except for pertussis toxin specific to B. pertussis.
- Acellular pertussis vaccines target major adhesins and pertussis toxin, which are protective antigens against B. pertussis.
Purpose of the Study:
- To evaluate the protective efficacy of B. pertussis virulence factors against B. parapertussis infection in a murine respiratory model.
- To investigate potential cross-protection between these closely related Bordetella species.
Main Methods:
- Utilized a murine respiratory model to assess the protective effects of Bordetella antigens.
- Administered specific virulence factors (pertussis toxin, filamentous hemagglutinin, pertactin, adenylate cyclase-hemolysin) and challenged with B. parapertussis.
Main Results:
- Pertussis toxin did not protect against B. parapertussis infection, as expected.
- Surprisingly, other B. pertussis virulence factors also failed to protect against B. parapertussis.
- B. parapertussis adenylate cyclase-hemolysin protected against its own species but not against B. pertussis, indicating a lack of cross-protection.
Conclusions:
- No cross-protection was observed between B. pertussis and B. parapertussis virulence factors, despite high genomic homology.
- Bordetella surface proteins exhibit significant immunological variation, impacting vaccine cross-reactivity.