Approaches to New Generation Vaccines against Pertussis and Identification of Virulence Factors

Gasperini, Gianmarco (2017) Approaches to New Generation Vaccines against Pertussis and Identification of Virulence Factors, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Biologia cellulare e molecolare, 29 Ciclo. DOI 10.6092/unibo/amsdottorato/8029.
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Despite high vaccination coverage world-wide, whooping cough, a highly contagious disease caused by Bordetella pertussis, is recently increasing in occurrence suggesting that novel vaccine formulations targeted at the prevention of colonization and transmission should be investigated. In order to identify new candidates for inclusion in the acellular formulation, we used spontaneously released outer membrane vesicles (OMV) as a potential source of key adhesins. In the first part of the study, we employed a proteomic approach to quantify proteins in OMV purified from bacteria in the Bvg+ and Bvg- phase, thus comparing the outer membrane protein pattern of this pathogen in its virulent or avirulent state. Six of the most abundant outer membrane proteins were selected as candidates to be evaluated for their adhesive properties and vaccine potential. We generated E. coli strains singularly expressing the selected proteins and assessed their ability to adhere to lung epithelial cells in vitro. Four out of the selected proteins conferred adhesive ability to E. coli. Three of the candidates were specifically detected by anti-OMV mouse serum suggesting that these proteins are immunogenic antigens able to elicit an antibody response when displayed on the OMV. Anti-OMV serum was able to inhibit only BrkA-expressing E. coli adhesion to lung epithelial cells. Finally, stand-alone immunization of mice with recombinant BrkA resulted in significant protection against infection of the lower respiratory tract after challenge with B. pertussis. In the second part of the study, we demonstrated that OMV are naturally released by B. pertussis in a human ciliated airway cell infection model. The purified vesicles interact with host cells, their binding and uptake are strictly Bvg-regulated and OMV-associated PT contributes to host cell intoxication. Furthermore we showed that OMV act as iron scavengers, reservoirs and delivery systems being able to complement B. pertussis growth defect in iron-limiting conditions.

Tipologia del documento
Tesi di dottorato
Gasperini, Gianmarco
Dottorato di ricerca
Settore disciplinare
Settore concorsuale
Parole chiave
pertussis, vaccine, outer membrane vescicles, pathogenesis, virulence factors
Data di discussione
21 Aprile 2017

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