Manuela Garibaldi

Novartis Vaccines, Cambridge, Massachusetts, United States

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Publications (7)29.14 Total impact

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    ABSTRACT: Bacterial lipoproteins are attractive vaccine candidates since they represent a major class of cell surface exposed proteins in many bacteria and are considered pathogen associated molecular patterns sensed by Toll like receptors with built in adjuvanticity. While Gram-negative lipoproteins are well studied, little is known about Gram positive lipoproteins. We isolated from Streptococcus pyogenes a high amount of lipoproteins organized in vesicles. These vesicles were obtained by weakening the bacterial cell wall after a mild treatment with penicillin. They were found to be enriched in phosphatidylglycerol and almost exclusively constituted by lipoproteins revealed as proteomic analysis. In association to the identified lipoproteins, few hypothetical proteins, penicillin binding proteins, and several members of the ExPortal, a membrane micro-domain responsible for the maturation of secreted proteins, were identified. The typical lipidic moiety was not necessary for the lipoprotein insertion in the vesicles bilayer since they were also recovered from the isogenic diacylglyceryl transferase deletion mutant. The vesicles were not able to activate specific Toll like receptor 2, indicating that lipoproteins organized in a vesicular structure do not act as pathogen-associated molecular patterns. In light of these findings, we propose to name these new structures Lipoprotein rich Membrane Vesicles. Copyright © 2015, The American Society for Biochemistry and Molecular Biology.
    Molecular &amp Cellular Proteomics 05/2015; DOI:10.1074/mcp.M114.045880 · 7.25 Impact Factor
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    ABSTRACT: We propose an experimental strategy for highly accurate selection of candidates for bacterial vaccines without using in vitro and/or in vivo protection assays. Starting from the observation that efficacious vaccines are constituted by conserved, surface-associated and/or secreted components, the strategy contemplates the parallel application of three high throughput technologies, i.e. mass spectrometry-based proteomics, protein array, and flow-cytometry analysis, to identify this category of proteins, and is based on the assumption that the antigens identified by all three technologies are the protective ones. When we tested this strategy for Group A Streptococcus, we selected a total of 40 proteins, of which only six identified by all three approaches. When the 40 proteins were tested in a mouse model, only six were found to be protective and five of these belonged to the group of antigens in common to the three technologies. Finally, a combination of three protective antigens conferred broad protection against a panel of four different Group A Streptococcus strains. This approach may find general application as an accelerated and highly accurate path to bacterial vaccine discovery.
    Molecular &amp Cellular Proteomics 01/2012; 11(6):M111.015693. DOI:10.1074/mcp.M111.015693 · 7.25 Impact Factor
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    ABSTRACT: Streptococcus suis serotype 2 is a major Gram-positive swine pathogen, causing also zoonoses. We describe here the immunoprotective activity in an in vivo animal model of a serotype-2 cell wall protein, designated Sat, which was identified by a previously validated proteomics approach consisting of the protease digestion of live bacteria and the selective recovery of exposed domains, followed by LC/MS/MS analysis. Increased survival rate (80%) and decreased bacterial burden were observed in mice immunized with a recombinant Sat fragment, suggesting that this protein is a potential vaccine candidate against serotype-2 infection.
    Journal of proteomics 11/2010; 73(12):2365-9. DOI:10.1016/j.jprot.2010.07.009 · 3.93 Impact Factor
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    ABSTRACT: Pili of gram-positive bacteria are key virulence factors and their subunits are considered excellent vaccine candidates. Streptococcus suis is an emerging zoonotic agent that can cause epidemics of life-threatening infections in humans, but the functional role or immunoprotective potential of its pilus components have not been studied yet. Using a selective proteomics approach, we have identified a surface protein of serotype 2 S. suis showing features of an ancillary pilus subunit, as evidenced by bioinformatics analysis, immunoblot and immunoelectron microscopy. Immunization with recombinant fragments of this protein, designated herein as PAPI-2b, markedly protected mice from systemic S. suis infection.
    Vaccine 04/2010; 28(20):3609-16. DOI:10.1016/j.vaccine.2010.01.009 · 3.49 Impact Factor
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    ABSTRACT: Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide. The ability of this bacterium to adhere to epithelial cells is considered as an essential early step in colonization and infection. By screening a whole genome phage display library with sera from infected patients, we previously identified three antigenic fragments matching open reading frame spr0075 of the strain R6 genome. This locus encodes for an approximately 120-kDa protein, herein referred to as plasminogen- and fibronectin-binding protein B (PfbB), which displays an LPXTG cell wall anchoring motif and six repetitive domains. In this study, by using isogenic pfbB-deleted mutants of the encapsulated D39 and of the unencapsulated DP1004 type 2 pneumococcal strains, we show that PfbB is involved in S. pneumoniae adherence to various epithelial respiratory tract cell lines. Our data suggest that PfbB directly mediates bacterial adhesion, because fluorescent beads coated with the recombinant PfbB sp17 fragment (encompassing one of the six repetitive domains and the C-terminal region) efficiently bound to epithelial cells. Mutants lacking PfbB bound to fibronectin and plasminogen considerably less efficiently than wild type bacteria, whereas sp17-coated beads specifically bound to both of these substrates. Taken together, our data suggest that, by directly interacting with fibronectin, PfbB significantly increases the ability of S. pneumoniae to adhere to human epithelial cells.
    Journal of Biological Chemistry 03/2010; 285(10):7517-24. DOI:10.1074/jbc.M109.062075 · 4.60 Impact Factor
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    ABSTRACT: Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide. The ability of this bacterium to adhere to epithelial cells is considered as an essential early step in colonization and infection. By screening a whole genome phage display library with sera from infected patients, we previously identified three antigenic fragments matching open reading frame spr0075 of the strain R6 genome. This locus encodes for an approximately 120-kDa protein, herein referred to as plasminogen- and fibronectin-binding protein B (PfbB), which displays an LPXTG cell wall anchoring motif and six repetitive domains. In this study, by using isogenic pfbB-deleted mutants of the encapsulated D39 and of the unencapsulated DP1004 type 2 pneumococcal strains, we show that PfbB is involved in S. pneumoniae adherence to various epithelial respiratory tract cell lines. Our data suggest that PfbB directly mediates bacterial adhesion, because fluorescent beads coated with the recombinant PfbB sp17 fragment (encompassing one of the six repetitive domains and the C-terminal region) efficiently bound to epithelial cells. Mutants lacking PfbB bound to fibronectin and plasminogen considerably less efficiently than wild type bacteria, whereas sp17-coated beads specifically bound to both of these substrates. Taken together, our data suggest that, by directly interacting with fibronectin, PfbB significantly increases the ability of S. pneumoniae to adhere to human epithelial cells.
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    ABSTRACT: Brucella melitensis and Brucella abortus are responsible for brucellosis in bovine and ovine species and for Malta fever in humans. The lipopolysaccharide (LPS) of Brucella is an important virulence factor and can elicit protective antibodies. Because of their potential importance in vaccine design and in serological diagnosis, we developed peptides mimicking the antigenic properties of distinctive antigenic determinants of Brucella LPS. These peptides were selected from several phage display random peptide libraries for their ability to bind monoclonal antibodies directed against the A- or C-type epitopes of Brucella LPS. Plasmids encoding for two of the isolated peptides induced, after DNA immunization, LPS-specific antibody responses. Although these responses were only moderate in extent, these data further suggest the feasibility of using peptide mimics of carbohydrate epitopes as immunogens, a property which may be useful in the design of novel anti-Brucella vaccines.
    Peptides 08/2009; 30(10):1936-9. DOI:10.1016/j.peptides.2009.07.009 · 2.61 Impact Factor

Publication Stats

99 Citations
29.14 Total Impact Points

Institutions

  • 2015
    • Novartis Vaccines
      Cambridge, Massachusetts, United States
  • 2009–2010
    • Università degli Studi di Messina
      • Dipartimento di Neuroscienze
      Messina, Sicily, Italy