Publications by authors named "Alessandro Vadi"

2 Publications

  • Page 1 of 1

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

Mol Cell Proteomics 2018 02 4;17(2):205-215. Epub 2017 Dec 4.

From the ‡GSK Vaccines, Siena, Italy

Despite high vaccination coverage world-wide, whooping cough, a highly contagious disease caused by 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) 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 to lung epithelial cells 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 strains singularly expressing the selected proteins and assessed their ability to adhere to lung epithelial cells Four out of the selected proteins conferred adhesive ability to 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 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 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.
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February 2018

Quantification by LC-MS(E) of outer membrane vesicle proteins of the Bexsero® vaccine.

Vaccine 2014 Mar 23;32(11):1273-9. Epub 2014 Jan 23.

Novartis Vaccines and Diagnostics, Via Fiorentina, 1 53100 Siena, Italy. Electronic address:

Meningococcal disease is a major cause of morbidity and mortality worldwide. Its epidemiology is currently dominated by five capsular serogroups (A, B, C, W, and Y). While effective vaccines already exist for serogroups A, C, W and Y, except for under clonal outbreaks, no vaccine was available against serogroup B. Recently, a four component vaccine, Bexsero(®), designed to prevent infection caused by this serogroup, has been approved in Europe and other Countries for use in individuals from two months of age and older. The active components of this vaccine are three recombinant proteins identified by reverse vaccinology combined with detergent extracted outer membrane vesicles (DOMV) prepared from a New Zealand epidemic strain. Considering their intrinsic complexity, we performed additional characterization of DOMVs on top of the standard quality control testing carried out for batch release. We applied the Hi3 label-free LC-MS(E) methodology to qualitatively and quantitatively characterize the DOMV protein content. We first, successfully investigated the robustness and the accuracy of the methodology for the DOMV characterization and we then applied it to compare six DOMV production lots. Around 100 proteins were quantified from each preparation. When classified according to their predicted cellular localization, about 90% of the total protein amount belongs consistently to the outer membrane compartment. Using nonparametric hypothesis testing and complementary log-log linear regression, the quantifications of a subset of 21 proteins common to all lots and including approximately 90% (85-92%) of the total protein amount quantified in any DOMV lot were found consistent across lots. The relevance of these results is two-fold, showing that the Hi3 quantification methodology is robust for a broad range of proteins and indicating that the manufacturing process currently used for the production of the Bexsero(®) DOMV components is highly reproducible and consistent.
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March 2014