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Boero E, Cruz AR, Pansegrau W, Giovani C, Rooijakkers SHM, van Kessel KPM, van Strijp JAG, Bagnoli F, Manetti AGO. Natural Human Immunity Against Staphylococcal Protein A Relies on Effector Functions Triggered by IgG3. Front Immunol 2022; 13:834711. [PMID: 35359919 PMCID: PMC8963248 DOI: 10.3389/fimmu.2022.834711] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 02/17/2022] [Indexed: 12/02/2022] Open
Abstract
Staphylococcal protein A (SpA) is a multifunctional, highly conserved virulence factor of Staphylococcus aureus. By binding the Fc portion of all human IgG subclasses apart from IgG3, SpA interferes with antibody and complement deposition on the bacterial surface, impairing staphylococcal clearance by phagocytosis. Because of its anti-opsonic properties, SpA is not investigated as a surface antigen to mediate bacterial phagocytosis. Herein we investigate human sera for the presence of SpA-opsonizing antibodies. The screening revealed that sera containing IgG3 against SpA were able to correctly opsonize the target and drive Fcγ receptor-mediated interactions and phagocytosis. We demonstrated that IgG3 Fc is significantly more efficient in inducing phagocytosis of SpA-expressing S. aureus as compared to IgG1 Fc in an assay resembling physiological conditions. Furthermore, we show that the capacity of SpA antibodies to induce phagocytosis depends on the specific epitope recognized by the IgGs on SpA molecules. Overall, our results suggest that anti-SpA IgG3 antibodies could favor the anti-staphylococcal response in humans, paving the way towards the identification of a correlate of protection against staphylococcal infections.
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Affiliation(s)
- Elena Boero
- GSK, Siena, Italy
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Ana Rita Cruz
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | | | | | - Suzan H. M. Rooijakkers
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Kok P. M. van Kessel
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Jos A. G. van Strijp
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
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2
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Cruz AR, van Strijp JAG, Bagnoli F, Manetti AGO. Virulence Gene Expression of Staphylococcus aureus in Human Skin. Front Microbiol 2021; 12:692023. [PMID: 34177874 PMCID: PMC8231915 DOI: 10.3389/fmicb.2021.692023] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 05/19/2021] [Indexed: 01/03/2023] Open
Abstract
Staphylococcus aureus is the main cause of human skin and soft tissue infections. However, S. aureus pathogenicity within the skin is not fully characterized. Here, we implemented an S. aureus cutaneous infection model using human skin explants and performed a time-course infection to study the gene expression profile of a large panel of virulence-related factors of S. aureus USA300 LAC strain, by high-throughput RT-PCR. We pinpointed the genes that were differentially regulated by the bacteria in the skin tissues and identified 12 virulence factors that were upregulated at all time points assessed. Finally, using confocal microscopy, we show that the expression of alpha-hemolysin by S. aureus varies dependent on the skin niche and that the bacteria preferentially accumulates inside sweat glands and ducts. Taken together, our study gives insights about the pathogenic lifestyle of S. aureus within human skin tissues, which may contribute for the development of anti-S. aureus therapeutic strategies.
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Affiliation(s)
| | - Jos A G van Strijp
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
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3
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Brignoli T, Manetti AGO, Rosini R, Haag AF, Scarlato V, Bagnoli F, Delany I. Absence of Protein A Expression Is Associated With Higher Capsule Production in Staphylococcal Isolates. Front Microbiol 2019; 10:863. [PMID: 31133995 PMCID: PMC6523524 DOI: 10.3389/fmicb.2019.00863] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 04/04/2019] [Indexed: 12/19/2022] Open
Abstract
Staphylococcus aureus is a major human pathogen, and a leading cause of soft tissue and blood stream infections. One of the causes of its success as a pathogen is the peculiar array of immune evasion factors through which the bacterium avoids host defenses, where the staphylococcal protein A (SpA) plays a major role thanks to its IgG binding activities. Moreover, SpA has recently been proposed as a promising vaccine antigen. In this study, we evaluated the expression of SpA in a collection of staphylococcal strains, about 7% of which did not express SpA (SpA- strains), despite the presence of the gene. By a comparative genomic analysis, we identified that a mutation in the spa 5′ UTR sequence affecting the RBS is responsible for the loss of SpA in a subset of SpA- strains. Using a high-throughput qRT-PCR approach on a selected panel of virulence-related genes, we identified that the SpA- phenotype is associated with lower spa transcript levels and increased expression and production of capsule as well as other changes in the transcription of several key virulence factors. Our data suggest that the SpA- phenotype has occurred in geographically distinct strains through different molecular mechanisms including both mutation, leading likely to translation alterations, and transcriptional deregulation. Furthermore, we provide evidence that SpA- strains are highly susceptible to phagocytic uptake mediated by anti-capsule antibodies. These data suggest that S. aureus may alter its virulence factor expression pattern as an adaptation to the host or environment. Vaccination strategies targeting both SpA and capsule could therefore result in broader coverage against staphylococcal isolates than SpA alone.
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Affiliation(s)
- Tarcisio Brignoli
- GSK Vaccines, Siena, Italy.,Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, Bologna, Italy
| | | | | | - Andreas F Haag
- GSK Vaccines, Siena, Italy.,Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Vincenzo Scarlato
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, Bologna, Italy
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4
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Viciani E, Montagnani F, Tordini G, Romano A, Salerni L, De Luca A, Ruggiero P, Manetti AGO. Prevalence of M75 Streptococcus pyogenes Strains Harboring slaA Gene in Patients Affected by Pediatric Obstructive Sleep Apnea Syndrome in Central Italy. Front Microbiol 2017; 8:294. [PMID: 28293224 PMCID: PMC5329643 DOI: 10.3389/fmicb.2017.00294] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 02/13/2017] [Indexed: 11/13/2022] Open
Abstract
Recently we reported an association between pediatric obstructive sleep apnea syndrome (OSAS) and Group A streptococcus (GAS) sub-acute chronic tonsil colonization. We showed that GAS may contribute to tonsil hyperplasia via a streptolysin O (SLO)-dependent cysteinyl leukotrienes (CysLTs) production, which can trigger T and B cell proliferation. In the present study, we characterized the GAS strains isolated from pediatric OSAS patients in comparison with a panel of age and sex matched GAS strains unrelated to OSAS, but isolated in the same area and during the same period ranging from 2009 to 2013. We found that slaA gene, previously reported to be associated to CysLTs production pathway, was significantly associated to GAS OSAS strains. Moreover, the most numerous group (32%) of the GAS OSAS strains belonged to M75 type, and 6 out of 7 of these strains harbored the slaA gene. Multilocus Sequence Typing (MLST) experiments demonstrated that the clone emm75/ST49/ smeZ, slaA was associated to OSAS cases. In conclusion, we found an association between slaA gene and the GAS OSAS strains, and we showed that the clone emm75/ST49 harboring genes smeZ and slaA was exclusively isolated from patients affected by OSAS, thus suggesting that this genotype might be associated to the pathogenesis of OSAS, although further studies are needed to elucidate the possible role of SlaA in tonsil hypertrophy development.
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Affiliation(s)
- Elisa Viciani
- GSK Vaccines S.r.l.Siena, Italy; Host-Microbiota Interaction Team, Wellcome Trust Sanger InstituteCambridge, UK
| | - Francesca Montagnani
- Department of Medical Biotechnologies, University of SienaSiena, Italy; Hospital Department of Specialized and Internal Medicine, University Division of Infectious DiseasesSiena, Italy
| | - Giacinta Tordini
- Department of Medical Biotechnologies, University of Siena Siena, Italy
| | - Antonio Romano
- Clinica Otorinolaringoiatrica, Policlinico Universitario "Le Scotte" Siena, Italy
| | - Lorenzo Salerni
- Clinica Otorinolaringoiatrica, Policlinico Universitario "Le Scotte" Siena, Italy
| | - Andrea De Luca
- Department of Medical Biotechnologies, University of SienaSiena, Italy; Hospital Department of Specialized and Internal Medicine, University Division of Infectious DiseasesSiena, Italy
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5
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Viciani E, Montagnani F, Tavarini S, Tordini G, Maccari S, Morandi M, Faenzi E, Biagini C, Romano A, Salerni L, Finco O, Lazzi S, Ruggiero P, De Luca A, Barocchi MA, Manetti AGO. Paediatric obstructive sleep apnoea syndrome (OSAS) is associated with tonsil colonisation by Streptococcus pyogenes. Sci Rep 2016; 6:20609. [PMID: 26860261 PMCID: PMC4748291 DOI: 10.1038/srep20609] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 01/08/2016] [Indexed: 12/11/2022] Open
Abstract
The involvement of pathogenic bacteria in obstructive sleep apnoea syndrome (OSAS) has yet to be elucidated. We investigated the possible role of group A streptococcus (GAS) in OSAS pathogenesis. In 40 tonsillectomized patients affected by OSAS and 80 healthy controls, significant (p < 0.0001) association of GAS with paediatric OSAS was found. Supernatant from streptolysin O (SLO)-producing GAS induced production of cysteinyl leukotrienes (CysLTs) in tonsil mononuclear cells (TMCs). CysLTs-treated TMCs showed significant (p < 0.05) proliferation of CD4+ T, CD19+ and CD19+CD27+CD38+ B lymphocytes. We discovered a SLO-dependent activation of CysLTs production through a pathway involving TOLL-like receptor 4 (TLR4), TIR-domain-containing adapter-inducing interferon-β (TRIF), Myeloid differentiation primary response gene 88 (MyD88), and p38 MAP Kinase. In conclusion, we hypothesise that GAS may contribute to paediatric tonsillar hyperplasia through CysLTs production induced by SLO, and this might explain its association with OSAS.
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Affiliation(s)
- Elisa Viciani
- GSK Vaccines S.r.l., Via Fiorentina, 1 53100 Siena, Italy
| | - Francesca Montagnani
- Department of Medical Biotechnologies, University of Siena, Viale Bracci 16, 53100 Siena, Italy.,University Division of Infectious Diseases, Hospital Department of Specialized and Internal Medicine, Viale Bracci 16, 53100 Siena, Italy
| | | | - Giacinta Tordini
- Department of Medical Biotechnologies, University of Siena, Viale Bracci 16, 53100 Siena, Italy
| | - Silvia Maccari
- GSK Vaccines S.r.l., Via Fiorentina, 1 53100 Siena, Italy
| | - Matteo Morandi
- Department of Medical Biotechnologies, University of Siena, Viale Bracci 16, 53100 Siena, Italy
| | - Elisa Faenzi
- GSK Vaccines S.r.l., Via Fiorentina, 1 53100 Siena, Italy
| | - Cesare Biagini
- Clinica Otorinolaringoiatrica, Policlinico Universitario "Le Scotte", Viale Bracci 16, 53100 Siena, Italy
| | - Antonio Romano
- Clinica Otorinolaringoiatrica, Policlinico Universitario "Le Scotte", Viale Bracci 16, 53100 Siena, Italy
| | - Lorenzo Salerni
- Clinica Otorinolaringoiatrica, Policlinico Universitario "Le Scotte", Viale Bracci 16, 53100 Siena, Italy
| | - Oretta Finco
- GSK Vaccines S.r.l., Via Fiorentina, 1 53100 Siena, Italy
| | - Stefano Lazzi
- Section of Pathology, Azienda Ospedaliera Universitaria Senese, Viale Bracci 16, 53100 Siena, Italy
| | - Paolo Ruggiero
- GSK Vaccines S.r.l., Via Fiorentina, 1 53100 Siena, Italy
| | - Andrea De Luca
- Department of Medical Biotechnologies, University of Siena, Viale Bracci 16, 53100 Siena, Italy.,University Division of Infectious Diseases, Hospital Department of Specialized and Internal Medicine, Viale Bracci 16, 53100 Siena, Italy
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6
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Becherelli M, Prachi P, Viciani E, Biagini M, Fiaschi L, Chiarot E, Nosari S, Brettoni C, Marchi S, Biancucci M, Fontana MR, Montagnani F, Bagnoli F, Barocchi MA, Manetti AGO. Protective activity of the CnaBE3 domain conserved among Staphylococcus aureus Sdr proteins. PLoS One 2013; 8:e74718. [PMID: 24069334 PMCID: PMC3775735 DOI: 10.1371/journal.pone.0074718] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 08/02/2013] [Indexed: 12/01/2022] Open
Abstract
Staphylococcus aureus is an opportunistic pathogen, commensal of the human skin and nares, but also responsible for invasive nosocomial as well as community acquired infections. Staphylococcus aureus adheres to the host tissues by means of surface adhesins, such as SdrC, SdrD, and SdrE proteins. The Sdr family of proteins together with a functional A domain, contain respectively two, three or five repeated sequences called B motifs which comprise the CnaB domains. SdrD and SdrE proteins were reported to be protective in animal models against invasive diseases or lethal challenge with human clinical S. aureus isolates. In this study we identified a 126 amino acid sequence containing a CnaB domain, conserved among the three Sdr proteins. The three fragments defined here as CnaBC2, D5 and E3 domains even though belonging to phylogenetically distinct strains, displayed high sequence similarity. Based on the sequence conservation data, we selected the CnaBE3 domain for further analysis and characterization. Polyclonal antibodies raised against the recombinant CnaBE3 domain recognized SdrE, SdrC and SdrD proteins of different S. aureus lineages. Moreover, we demonstrated that the CnaBE3 domain was expressed in vivo during S. aureus infections, and that immunization of this domain alone significantly reduces the bacterial load in mice challenged with S. aureus. Furthermore, we show that the reduction of bacteria by CnaBE3 vaccination is due to functional antibodies. Finally, we demonstrated that the region of the SdrE protein containing the CnaBE3 domain was resistant to trypsin digestion, a characteristic often associated with the presence of an isopeptide bond.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Sara Marchi
- Novartis Vaccines and Diagnostics, Siena, Italy
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7
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Bensi G, Mora M, Tuscano G, Biagini M, Chiarot E, Bombaci M, Capo S, Falugi F, Manetti AGO, Donato P, Swennen E, Gallotta M, Garibaldi M, Pinto V, Chiappini N, Musser JM, Janulczyk R, Mariani M, Scarselli M, Telford JL, Grifantini R, Norais N, Margarit I, Grandi G. Multi high-throughput approach for highly selective identification of vaccine candidates: the Group A Streptococcus case. Mol Cell Proteomics 2012; 11:M111.015693. [PMID: 22286755 PMCID: PMC3433891 DOI: 10.1074/mcp.m111.015693] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 01/05/2012] [Indexed: 11/23/2022] Open
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.
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Affiliation(s)
- Giuliano Bensi
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Marirosa Mora
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Giovanna Tuscano
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Massimiliano Biagini
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Emiliano Chiarot
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Mauro Bombaci
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Sabrina Capo
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Fabiana Falugi
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Andrea G. O. Manetti
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Paolo Donato
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Erwin Swennen
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Marilena Gallotta
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Manuela Garibaldi
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Vittoria Pinto
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Nico Chiappini
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - James M. Musser
- §Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, Houston, Texas 77030
| | - Robert Janulczyk
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Massimo Mariani
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Maria Scarselli
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - John L. Telford
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Renata Grifantini
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Nathalie Norais
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Immaculada Margarit
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
| | - Guido Grandi
- From the ‡Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
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8
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Becherelli M, Manetti AGO, Buccato S, Viciani E, Ciucchi L, Mollica G, Grandi G, Margarit I. The ancillary protein 1 of Streptococcus pyogenes FCT-1 pili mediates cell adhesion and biofilm formation through heterophilic as well as homophilic interactions. Mol Microbiol 2012; 83:1035-47. [PMID: 22320452 PMCID: PMC3490378 DOI: 10.1111/j.1365-2958.2012.07987.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Gram-positive pili are known to play a role in bacterial adhesion to epithelial cells and in the formation of biofilm microbial communities. In the present study we undertook the functional characterization of the pilus ancillary protein 1 (AP1_M6) from Streptococcus pyogenes isolates expressing the FCT-1 pilus variant, known to be strong biofilm formers. Cell binding and biofilm formation assays using S. pyogenes in-frame deletion mutants, Lactococcus expressing heterologous FCT-1 pili and purified recombinant AP1_M6, indicated that this pilin is a strong cell adhesin that is also involved in bacterial biofilm formation. Moreover, we show that AP1_M6 establishes homophilic interactions that mediate inter-bacterial contact, possibly promoting bacterial colonization of target epithelial cells in the form of three-dimensional microcolonies. Finally, AP1_M6 knockout mutants were less virulent in mice, indicating that this protein is also implicated in GAS systemic infection.
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Affiliation(s)
- Marco Becherelli
- Novartis Vaccines and Diagnostics, Via Fiorentina 1, Siena, Italy
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9
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Manetti AGO, Köller T, Becherelli M, Buccato S, Kreikemeyer B, Podbielski A, Grandi G, Margarit I. Environmental acidification drives S. pyogenes pilus expression and microcolony formation on epithelial cells in a FCT-dependent manner. PLoS One 2010; 5:e13864. [PMID: 21079780 PMCID: PMC2974651 DOI: 10.1371/journal.pone.0013864] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Accepted: 10/18/2010] [Indexed: 01/24/2023] Open
Abstract
Group A Streptococcus (GAS, Streptococcus pyogenes) is a Gram-positive human pathogen responsible for a diverse variety of diseases, including pharyngitis, skin infections, invasive necrotizing fasciitis and autoimmune sequelae. We have recently shown that GAS cell adhesion and biofilm formation is associated with the presence of pili on the surface of these bacteria. GAS pilus proteins are encoded in the FCT (Fibronectin- Collagen-T antigen) genomic region, of which nine different variants have been identified so far. In the present study we undertook a global analysis of GAS isolates representing the majority of FCT-variants to investigate the effect of environmental growth conditions on their capacity to form multicellular communities. For FCT-types 2, 3, 5 and 6 and a subset of FCT-4 strains, we observed that acidification resulting from fermentative sugar metabolism leads to an increased ability of the bacteria to form biofilm on abiotic surfaces and microcolonies on epithelial cells. The higher biofilm forming capacity at low environmental pH was directly associated with an enhanced expression of the genes encoding the pilus components and of their transcription regulators. The data indicate that environmental pH affects the expression of most pilus types and thereby the formation of multicellular cell-adhering communities that assist the initial steps of GAS infection.
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Affiliation(s)
| | - Thomas Köller
- Institute of Medical Microbiology, Virology and Hygiene, Rostock, Germany
| | | | | | - Bernd Kreikemeyer
- Institute of Medical Microbiology, Virology and Hygiene, Rostock, Germany
| | - Andreas Podbielski
- Institute of Medical Microbiology, Virology and Hygiene, Rostock, Germany
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10
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Edwards AM, Manetti AGO, Falugi F, Zingaretti C, Capo S, Buccato S, Bensi G, Telford JL, Margarit I, Grandi G. Scavenger receptor gp340 aggregates group A streptococci by binding pili. Mol Microbiol 2008; 68:1378-94. [PMID: 18452511 DOI: 10.1111/j.1365-2958.2008.06220.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Group A streptococci (GAS) are the most frequent cause of bacterial pharyngitis. The first obstacle to GAS colonization of the pharynx is saliva. As well as forming a physical barrier, saliva contains components of innate and acquired immunity. Previous work has shown that saliva induces bacterial aggregation, which may serve as a clearance mechanism. As the aggregation of some oral streptococci in saliva is mediated by long proteinaceous appendages, we hypothesized that pili of GAS might behave similarly. Wild-type GAS M1 strain SF370 aggregated in saliva, while pilus-defective mutants did not. Similarly, heterologous expression of diverse GAS pili on the surface of Lactococcus lactis induced aggregation in saliva, while control strains were unaffected. Further studies revealed that aggregating bacteria bound salivary component gp340. Purified gp340 aggregated wild-type GAS and L. lactis expressing GAS pili, but not control strains. GAS pilus-defective mutants were abrogated in gp340 binding and aggregation. Furthermore, gp340-mediated aggregation reduced bacterial adhesion to human epithelial cells, suggesting a role in host defence.
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11
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Manetti AGO, Zingaretti C, Falugi F, Capo S, Bombaci M, Bagnoli F, Gambellini G, Bensi G, Mora M, Edwards AM, Musser JM, Graviss EA, Telford JL, Grandi G, Margarit I. Streptococcus pyogenes pili promote pharyngeal cell adhesion and biofilm formation. Mol Microbiol 2007; 64:968-83. [PMID: 17501921 DOI: 10.1111/j.1365-2958.2007.05704.x] [Citation(s) in RCA: 185] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Group A Streptococcus (GAS, Streptococcus pyogenes) is a Gram-positive human pathogen responsible for several acute diseases and autoimmune sequelae that account for half a million deaths worldwide every year. GAS infections require the capacity of the pathogen to adhere to host tissues and assemble in cell aggregates. Furthermore, a role for biofilms in GAS pathogenesis has recently been proposed. Here we investigated the role of GAS pili in biofilm formation. We demonstrated that GAS pilus-negative mutants, in which the genes encoding either the pilus backbone structural protein or the sortase C1 have been deleted, showed an impaired capacity to attach to a pharyngeal cell line. The same mutants were much less efficient in forming cellular aggregates in liquid culture and microcolonies on human cells. Furthermore, mutant strains were incapable of producing the typical three-dimensional layer with bacterial microcolonies embedded in a carbohydrate polymeric matrix. Complemented mutants had an adhesion and aggregation phenotype similar to the wild-type strain. Finally, in vivo expression of pili was indirectly confirmed by demonstrating that most of the sera from human patients affected by GAS-mediated pharyngitis recognized recombinant pili proteins. These data support the role of pili in GAS adherence and colonization and suggest a general role of pili in all pathogenic streptococci.
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Affiliation(s)
- Andrea G O Manetti
- Novartis Vaccines and Diagnostics, Via Fiorentina 1, 53100, Siena, Italy
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Mora M, Bensi G, Capo S, Falugi F, Zingaretti C, Manetti AGO, Maggi T, Taddei AR, Grandi G, Telford JL. Group A Streptococcus produce pilus-like structures containing protective antigens and Lancefield T antigens. Proc Natl Acad Sci U S A 2005; 102:15641-6. [PMID: 16223875 PMCID: PMC1253647 DOI: 10.1073/pnas.0507808102] [Citation(s) in RCA: 294] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2005] [Indexed: 11/18/2022] Open
Abstract
Although pili have long been recognized in Gram-negative pathogens as important virulence factors involved in adhesion and invasion, very little is known about extended surface organelles in Gram-positive pathogens. Here we report that Group A Streptococcus (GAS), a Gram-positive human-specific pathogen that causes pharyngitis, impetigo, invasive disease, necrotizing fasciitis, and autoimmune sequelae has long, surface-exposed, pilus-like structures composed of members of a family of extracellular matrix-binding proteins. We describe four variant pili and show that each is recognized by a specific serum of the Lancefield T-typing system, which has been used for over five decades to characterize GAS isolates. Furthermore, we show that immunization of mice with a combination of recombinant pilus proteins confers protection against mucosal challenge with virulent GAS bacteria. The data indicate that induction of a protective immune response against these structures may be a useful strategy for development of a vaccine against disease caused by GAS infection.
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Affiliation(s)
- Marirosa Mora
- Chiron Vaccines, Via Fiorentina 1, 53100 Siena, Italy
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