Outer Membrane Vesicles (OMV)-based and Proteomics-driven Antigen Selection Identifies Novel Factors Contributing to Bordetella pertussis Adhesion to Epithelial Cells

Abstract

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. To identify new candidates for inclusion in the acellular formulation, we used spontaneously released outer membrane vesicles (OMV)1 as a potential source of key adhesins. The enrichment of Bvg+ OMV with adhesins and the ability of anti-OMV serum to inhibit the adhesion of B. pertussis to lung epithelial cells in vitro were demonstrated. We employed a proteomic approach to identify the differentially expressed proteins in OMV purified from bacteria in the Bvg+ and Bvg− virulence phases, 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. Taken together, these data support the inclusion of BrkA and possibly further adhesins to the current acellular pertussis vaccines to improve the impact of vaccination on the bacterial clearance.

Outer-Membrane-Vesicle–Associated O Antigen, a Crucial Component for Protecting Against Bordetella parapertussis Infection

“…The differential protective capability associated with the presence of the O antigen was confirmed with preparations of purified LPS-O + or LPS-O − as vaccines. Furthermore, the LPS-O + provided a protection against B. parapertussis infections even when combined with OMVsBpp containing LPS devoid of the O antigen or with OMVs derived from B. pertussis which was previously described as an atractive vaccine candidate againt B. pertussis infection containing an important number of protective immunogens ( 20 , 22 , 23 ). Of particular significance in that last formulation combining the OMVs of B. pertussis with the LPS-O + from B. parapertussis was the ability to protect mice against infections caused by either Bordetella species—a feature of considerable relevance to pertussis epidemiology with respect to both B. pertussis and B. parapertussis .…”

Immunomodulation as a Novel Strategy for Prevention and Treatment of Bordetella spp. Infections

“…Several groups are currently working on the development of outer membrane vesicles and outer membrane proteins in protection against B. pertussis as well as cross-protection against several Bordetella spp. and characterizing the immune response as well as protective immunity (285)(286)(287)(288)(289)(290)(291)(292)(293)(294)(295). In animal studies, immunization with outer membrane vesicles led to not only better humoral and cellular (Th17) memory, but also to a significant increase in IgA titers, which is one of the major hurdles of current vaccination strategies against this pathogen (296)(297)(298).…”

Proteomic analysis of bacterial (outer) membrane vesicles: progress and clinical potential

“…By employing metabolic labeling techniques, quantitative comparisons of the OMVs and the outer membrane regarding their protein composition lead to insights into the dynamic functions of the OMVs in the context of pathogenesis [21] and within bacterial communities. Further, the utilization of proteomic techniques and determination the OMV proteome is of interest for the understanding of the physiology of their biogenesis or in case of vaccine development for the identification of putative immunogens [22]. Moreover, it is helpful to check the successful incorporation of heterologous or hybridized proteins in bioengineered vesicles.…”