The Role of Fimbriae in Bordetella Colonization

Open Access
Author:
Dunagin, Margaret Curry
Area of Honors:
Microbiology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Eric Thomas Harvill, Thesis Supervisor
  • Donald Ashley Bryant, Honors Advisor
  • Scott Brian Selleck, Faculty Reader
Keywords:
  • Bordetella bronchiseptica
  • B. pertussis
  • B. parapertussis
  • fimbriae
Abstract:
Bordetella bronchiseptica is a respiratory tract pathogen of many mammalian species that is closely related to B. pertussis and B. parapertussis, the causative agents of whooping cough. Fimbriae are little-studied adhesins of the Bordetella and are a component of the B. pertussis acellular vaccine. In this study, we explored the role of fimbriae in murine B. bronchiseptica infection and began constructing fimbrial mutants of B. pertussis and B. parapertussis for future investigations of these human pathogens. We show that there is no statistically significant difference in colonization of the mouse respiratory tract between a wild type B. bronchiseptica strain and a fimbrial mutant following a high-dose, high-volume inoculation, but that fimbriae may be an important factor in dissemination of infection throughout the respiratory tract when a low-dose, low-volume inoculation method is used. Furthermore, there was a statistically significant higher IgG3 antibody titer observed in C57Bl/6 mice infected with the fimbrial mutant compared to the parental strain. We also show that the fimbrial mutant is substantially less likely to cause lethal bordetellosis in mice deficient in TNF-α than wild type B. bronchiseptica. Plasmids were constructed for the creation of fimbrial mutants of B. parapertussis and are being developed for B. pertussis knockouts. Together, our data indicate that fimbriae may play a role in dissemination of bacteria throughout the respiratory tract and suggest fimbriae are involved in immune system regulation.