1
|
Rohokale R, Guo Z. Development in the Concept of Bacterial Polysaccharide Repeating Unit-Based Antibacterial Conjugate Vaccines. ACS Infect Dis 2023; 9:178-212. [PMID: 36706246 PMCID: PMC9930202 DOI: 10.1021/acsinfecdis.2c00559] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The surface of cells is coated with a dense layer of glycans, known as the cell glycocalyx. The complex glycans in the glycocalyx are involved in various biological events, such as bacterial pathogenesis, protection of bacteria from environmental stresses, etc. Polysaccharides on the bacterial cell surface are highly conserved and accessible molecules, and thus they are excellent immunological targets. Consequently, bacterial polysaccharides and their repeating units have been extensively studied as antigens for the development of antibacterial vaccines. This Review surveys the recent developments in the synthetic and immunological investigations of bacterial polysaccharide repeating unit-based conjugate vaccines against several human pathogenic bacteria. The major challenges associated with the development of functional carbohydrate-based antibacterial conjugate vaccines are also considered.
Collapse
|
2
|
Abstract
Glycoscience assembles all the scientific disciplines involved in studying various molecules and macromolecules containing carbohydrates and complex glycans. Such an ensemble involves one of the most extensive sets of molecules in quantity and occurrence since they occur in all microorganisms and higher organisms. Once the compositions and sequences of these molecules are established, the determination of their three-dimensional structural and dynamical features is a step toward understanding the molecular basis underlying their properties and functions. The range of the relevant computational methods capable of addressing such issues is anchored by the specificity of stereoelectronic effects from quantum chemistry to mesoscale modeling throughout molecular dynamics and mechanics and coarse-grained and docking calculations. The Review leads the reader through the detailed presentations of the applications of computational modeling. The illustrations cover carbohydrate-carbohydrate interactions, glycolipids, and N- and O-linked glycans, emphasizing their role in SARS-CoV-2. The presentation continues with the structure of polysaccharides in solution and solid-state and lipopolysaccharides in membranes. The full range of protein-carbohydrate interactions is presented, as exemplified by carbohydrate-active enzymes, transporters, lectins, antibodies, and glycosaminoglycan binding proteins. A final section features a list of 150 tools and databases to help address the many issues of structural glycobioinformatics.
Collapse
Affiliation(s)
- Serge Perez
- Centre de Recherche sur les Macromolecules Vegetales, University of Grenoble-Alpes, Centre National de la Recherche Scientifique, Grenoble F-38041, France
| | - Olga Makshakova
- FRC Kazan Scientific Center of Russian Academy of Sciences, Kazan Institute of Biochemistry and Biophysics, Kazan 420111, Russia
| |
Collapse
|
3
|
van
der Put RMF, Smitsman C, de Haan A, Hamzink M, Timmermans H, Uittenbogaard J, Westdijk J, Stork M, Ophorst O, Thouron F, Guerreiro C, Sansonetti PJ, Phalipon A, Mulard LA. The First-in-Human Synthetic Glycan-Based Conjugate Vaccine Candidate against Shigella. ACS CENTRAL SCIENCE 2022; 8:449-460. [PMID: 35559427 PMCID: PMC9088300 DOI: 10.1021/acscentsci.1c01479] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Indexed: 05/12/2023]
Abstract
Shigella, the causative agent of shigellosis, is among the main causes of diarrheal diseases with still a high morbidity in low-income countries. Relying on chemical synthesis, we implemented a multidisciplinary strategy to design SF2a-TT15, an original glycoconjugate vaccine candidate targeting Shigella flexneri 2a (SF2a). Whereas the SF2a O-antigen features nonstoichiometric O-acetylation, SF2a-TT15 is made of a synthetic 15mer oligosaccharide, corresponding to three non-O-acetylated repeats, linked at its reducing end to tetanus toxoid by means of a thiol-maleimide spacer. We report on the scale-up feasibility under GMP conditions of a high yielding bioconjugation process established to ensure a reproducible and controllable glycan/protein ratio. Preclinical and clinical batches complying with specifications from ICH guidelines, WHO recommendations for polysaccharide conjugate vaccines, and (non)compendial tests were produced. The obtained SF2a-TT15 vaccine candidate passed all toxicity-related criteria, was immunogenic in rabbits, and elicited bactericidal antibodies in mice. Remarkably, the induced IgG antibodies recognized a large panel of SF2a circulating strains. These preclinical data have paved the way forward to the first-in-human study for SF2a-TT15, demonstrating safety and immunogenicity. This contribution discloses the yet unreported feasibility of the GMP synthesis of conjugate vaccines featuring a unique homogeneous synthetic glycan hapten fine-tuned to protect against an infectious disease.
Collapse
Affiliation(s)
| | | | - Alex de Haan
- Intravacc, P.O. Box 450, 3720 AL Bilthoven, The Netherlands
| | - Martin Hamzink
- Intravacc, P.O. Box 450, 3720 AL Bilthoven, The Netherlands
| | | | | | - Janny Westdijk
- Intravacc, P.O. Box 450, 3720 AL Bilthoven, The Netherlands
| | - Michiel Stork
- Intravacc, P.O. Box 450, 3720 AL Bilthoven, The Netherlands
| | - Olga Ophorst
- Intravacc, P.O. Box 450, 3720 AL Bilthoven, The Netherlands
| | - Françoise Thouron
- Institut
Pasteur, U1202 Inserm, Unité
de Pathogénie Microbienne Moléculaire, 28 rue du Dr Roux, 75724 Paris Cedex 15, France
| | - Catherine Guerreiro
- Institut
Pasteur, Université Paris Cité, CNRS UMR3523, Unité de Chimie des Biomolécules, 28 rue du Dr Roux, 75724 Paris Cedex 15, France
| | - Philippe J. Sansonetti
- Institut
Pasteur, U1202 Inserm, Unité
de Pathogénie Microbienne Moléculaire, 28 rue du Dr Roux, 75724 Paris Cedex 15, France
- Chaire
de Microbiologie et Maladies Infectieuses, Collège de France, 11, place Marcelin Berthelot, 75005 Paris, France
| | - Armelle Phalipon
- Institut
Pasteur, U1202 Inserm, Unité
de Pathogénie Microbienne Moléculaire, 28 rue du Dr Roux, 75724 Paris Cedex 15, France
| | - Laurence A. Mulard
- Institut
Pasteur, Université Paris Cité, CNRS UMR3523, Unité de Chimie des Biomolécules, 28 rue du Dr Roux, 75724 Paris Cedex 15, France
| |
Collapse
|
4
|
Toward a Multivalent Synthetic Oligosaccharide-Based Conjugate Vaccine against Shigella: State-of-the-Art for a Monovalent Prototype and Challenges. Vaccines (Basel) 2022; 10:vaccines10030403. [PMID: 35335035 PMCID: PMC8954881 DOI: 10.3390/vaccines10030403] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 02/15/2022] [Accepted: 02/19/2022] [Indexed: 02/04/2023] Open
Abstract
This review focuses on the molecular glycovaccine concept, a promising option to develop a Shigella glycoconjugate vaccine. Subsequent to original developments involving, as main vaccine component, the detoxified Shigella lipopolysaccharide randomly conjugated at multiple sites to a carrier protein, novelty stems from the use of rationally designed, well-defined chemically synthesized oligosaccharide haptens conceived as functional surrogates of the main surface antigen, linked via single-point attachment onto a carrier. The concept and design of such a fine-tuned Shigella glycovaccine are presented by way of SF2a-TT15, a neoglycoprotein featuring a synthetic 15-mer oligosaccharide, which constitutes an original vaccine prototype targeting Shigella flexneri 2a, one of the predominant circulating strains in endemic settings. The clinical testing of SF2a-TT15 is summarized with the first-in-human phase I trial in young healthy adults showing a good safety profile and tolerability, while inducing bactericidal antibodies towards S. flexneri 2a bacteria. The proof-of-concept of this novel approach being established, an ongoing phase IIa clinical study in the nine-month-old infant target population in endemic area was launched, which is also outlined. Lastly, some challenges to move forward this original approach toward a multivalent cost-effective Shigella synthetic glycan conjugate vaccine are introduced.
Collapse
|
5
|
Citiulo F, Necchi F, Mancini F, Rossi O, Aruta MG, Gasperini G, Alfini R, Rondini S, Micoli F, Rappuoli R, Saul A, Martin LB. Rationalizing the design of a broad coverage Shigella vaccine based on evaluation of immunological cross-reactivity among S. flexneri serotypes. PLoS Negl Trop Dis 2021; 15:e0009826. [PMID: 34644291 PMCID: PMC8589205 DOI: 10.1371/journal.pntd.0009826] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 11/12/2021] [Accepted: 09/21/2021] [Indexed: 11/21/2022] Open
Abstract
No vaccine to protect against an estimated 238,000 shigellosis deaths per year is widely available. S. sonnei is the most prevalent Shigella, and multiple serotypes of S. flexneri, which change regionally and globally, also cause significant disease. The leading Shigella vaccine strategies are based on the delivery of serotype specific O-antigens. A strategy to minimize the complexity of a broadly-protective Shigella vaccine is to combine components from S. sonnei with S. flexneri serotypes that induce antibodies with maximum cross-reactivity between different serotypes. We used the GMMA-technology to immunize animal models and generate antisera against 14 S. flexneri subtypes from 8 different serotypes that were tested for binding to and bactericidal activity against a panel of 11 S. flexneri bacteria lines. Some immunogens induced broadly cross-reactive antibodies that interacted with most of the S. flexneri in the panel, while others induced antibodies with narrower specificity. Most cross-reactivity could not be assigned to modifications of the O-antigen, by glucose, acetate or phosphoethanolamine, common to several of the S. flexneri serotypes. This allowed us to revisit the current dogma of cross-reactivity among S. flexneri serotypes suggesting that a broadly protective vaccine is feasible with limited number of appropriately selected components. Thus, we rationally designed a 4-component vaccine selecting GMMA from S. sonnei and S. flexneri 1b, 2a and 3a. The resulting formulation was broadly cross-reactive in mice and rabbits, inducing antibodies that killed all S. flexneri serotypes tested. This study provides the framework for a broadly-protective Shigella vaccine which needs to be verified in human trials. A strategy to optimize the composition for a broadly-protective Shigella vaccine is to combine components directed against S. sonnei with S. flexneri serotypes to induce antibody responses with the maximum cross-reactivity between different serotypes. Based on mouse and rabbit immunogenicity, we selected 4 GMMA-immunogens, derived from S. sonnei and S. flexneri 1b, 2a and 3a, able to induce antibodies that were broadly bactericidal against most epidemiologically significant S. flexneri strains in mice and rabbits. This was not predicted on the basis of O-antigen modifications conferring serotype or group specificities and allowed revisiting the dogma of cross-protection among S. flexneri serotypes. Overall, this study provides a framework for the rational design of a broadly-protective vaccine that will be evaluated in upcoming human vaccine trials. It also tackles a key issue regarding Shigella vaccine development that is balancing a sufficient number of antigenic components in the vaccine to provide adequate coverage of serotype diversity while minimizing complexity.
Collapse
Affiliation(s)
- Francesco Citiulo
- GSK Vaccines Institute for Global Health S.r.l. (GVGH), Siena, Italy
- * E-mail:
| | - Francesca Necchi
- GSK Vaccines Institute for Global Health S.r.l. (GVGH), Siena, Italy
| | - Francesca Mancini
- GSK Vaccines Institute for Global Health S.r.l. (GVGH), Siena, Italy
| | - Omar Rossi
- GSK Vaccines Institute for Global Health S.r.l. (GVGH), Siena, Italy
| | | | | | - Renzo Alfini
- GSK Vaccines Institute for Global Health S.r.l. (GVGH), Siena, Italy
| | | | - Francesca Micoli
- GSK Vaccines Institute for Global Health S.r.l. (GVGH), Siena, Italy
| | | | - Allan Saul
- GSK Vaccines Institute for Global Health S.r.l. (GVGH), Siena, Italy
| | - Laura B. Martin
- GSK Vaccines Institute for Global Health S.r.l. (GVGH), Siena, Italy
| |
Collapse
|
6
|
Conformational and Immunogenicity Studies of the Shigella flexneri Serogroup 6 O-Antigen: The Effect of O-Acetylation. Vaccines (Basel) 2021; 9:vaccines9050432. [PMID: 33925465 PMCID: PMC8144980 DOI: 10.3390/vaccines9050432] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/21/2021] [Accepted: 04/21/2021] [Indexed: 01/30/2023] Open
Abstract
The pathogenic bacterium Shigella is a leading cause of diarrheal disease and mortality, disproportionately affecting young children in low-income countries. The increasing prevalence of antibiotic resistance in Shigella necessitates an effective vaccine, for which the bacterial lipopolysaccharide O-antigen is the primary target. S. flexneri serotype 6 has been proposed as a multivalent vaccine component to ensure broad protection against Shigella. We have previously explored the conformations of S. flexneri O-antigens from serogroups Y, 2, 3, and 5 that share a common saccharide backbone (serotype Y). Here we consider serogroup 6, which is of particular interest because of an altered backbone repeat unit with non-stoichiometric O-acetylation, the antigenic and immunogenic importance of which have yet to be established. Our simulations show significant conformational changes in serogroup 6 relative to the serotype Y backbone. We further find that O-acetylation has little effect on conformation and hence may not be essential for the antigenicity of serotype 6. This is corroborated by an in vivo study in mice, using Generalized Modules for Membrane Antigens (GMMA) as O-antigen delivery systems, that shows that O-acetylation does not have an impact on the immune response elicited by the S. flexneri serotype 6 O-antigen.
Collapse
|
7
|
Cornil J, Hu Z, Bouchet M, Mulard LA. Multigram synthesis of an orthogonally-protected pentasaccharide for use as a glycan precursor in a Shigella flexneri 3a conjugate vaccine: application to a ready-for-conjugation decasaccharide. Org Chem Front 2021. [DOI: 10.1039/d1qo00761k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Fine-tuned catalytic processes facilitating regio- and stereoselective conversions for the large-scale synthesis of a pentasaccharide and its oligomerization into ready-for-conjugation haptens.
Collapse
Affiliation(s)
- Johan Cornil
- Unité de Chimie des Biomolécules, Institut Pasteur, UMR3523 CNRS, 28 rue du Dr Roux, 75 724 Paris Cedex 15, France
| | - Zhaoyu Hu
- Unité de Chimie des Biomolécules, Institut Pasteur, UMR3523 CNRS, 28 rue du Dr Roux, 75 724 Paris Cedex 15, France
| | - Marion Bouchet
- Unité de Chimie des Biomolécules, Institut Pasteur, UMR3523 CNRS, 28 rue du Dr Roux, 75 724 Paris Cedex 15, France
| | - Laurence A. Mulard
- Unité de Chimie des Biomolécules, Institut Pasteur, UMR3523 CNRS, 28 rue du Dr Roux, 75 724 Paris Cedex 15, France
| |
Collapse
|
8
|
Hlozek J, Owen S, Ravenscroft N, Kuttel MM. Molecular Modeling of the Shigella flexneri Serogroup 3 and 5 O-Antigens and Conformational Relationships for a Vaccine Containing Serotypes 2a and 3a. Vaccines (Basel) 2020; 8:vaccines8040643. [PMID: 33147882 PMCID: PMC7712985 DOI: 10.3390/vaccines8040643] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/09/2020] [Accepted: 10/29/2020] [Indexed: 12/12/2022] Open
Abstract
The pathogenic bacterium Shigella flexneri is a leading global cause of diarrheal disease. The O-antigen is the primary vaccine target and distinguishes the 30 serotypes reported. Except for serotype 6, all S. flexneri serotypes have a common backbone repeating unit (serotype Y), with variations in substitution creating the various serotypes. A quadrivalent vaccine containing serotypes 2a and 3a (as well as 6 and Shigella sonnei) is proposed to provide broad protection against non-vaccine S. flexneri serotypes through shared epitopes and conformations. Here we model the O-antigen (O-Ag) conformations of serogroups 3 and 5: a continuation of our ongoing systematic study of the S. flexneri O-antigens that began with serogroup 2. Our simulations show that S. flexneri serogroups 2, 3, and 5 all have flexible O-Ags, with substitutions of the backbone altering the chain conformations in different ways. Our analysis suggests three general heuristics for the effects of substitution on the Shigella O-Ag conformations: (1) substitution on rhamnose C reduces the extension of the O-Ag chain; (2) substitution at O-3 of rhamnose A restricts the O-Ags to predominantly helical conformations, (3) substitution at O-3 of rhamnose B has only a slight effect on conformation. The common O-Ag conformations across serotypes identified in this work support the assumption that a quadrivalent vaccine containing serotypes 2a and 3a could provide coverage against S. flexneri serotype 3b and serogroup 5.
Collapse
Affiliation(s)
- Jason Hlozek
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa; (J.H.); (N.R.)
| | - Sara Owen
- Department of Computer Science, University of Cape Town, Rondebosch 7701, South Africa;
| | - Neil Ravenscroft
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa; (J.H.); (N.R.)
| | - Michelle M. Kuttel
- Department of Computer Science, University of Cape Town, Rondebosch 7701, South Africa;
- Correspondence:
| |
Collapse
|
9
|
Whitfield C, Williams DM, Kelly SD. Lipopolysaccharide O-antigens-bacterial glycans made to measure. J Biol Chem 2020; 295:10593-10609. [PMID: 32424042 DOI: 10.1074/jbc.rev120.009402] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 05/17/2020] [Indexed: 01/05/2023] Open
Abstract
Lipopolysaccharides are critical components of bacterial outer membranes. The more conserved lipid A part of the lipopolysaccharide molecule is a major element in the permeability barrier imposed by the outer membrane and offers a pathogen-associated molecular pattern recognized by innate immune systems. In contrast, the long-chain O-antigen polysaccharide (O-PS) shows remarkable structural diversity and fulfills a range of functions, depending on bacterial lifestyles. O-PS production is vital for the success of clinically important Gram-negative pathogens. The biological properties and functions of O-PSs are mostly independent of specific structures, but the size distribution of O-PS chains is particularly important in many contexts. Despite the vast O-PS chemical diversity, most are produced in bacterial cells by two assembly strategies, and the different mechanisms employed in these pathways to regulate chain-length distribution are emerging. Here, we review our current understanding of the mechanisms involved in regulating O-PS chain-length distribution and discuss their impact on microbial cell biology.
Collapse
Affiliation(s)
- Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Danielle M Williams
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Steven D Kelly
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| |
Collapse
|
10
|
Development and Validation of a Procedure for Authenticity Verification of Modified Lipopolysaccharides of Shigella flexneri Subtypes 1b, 2a, 3a, 6, and Y by 13C NMR Spectroscopy. Pharm Chem J 2020. [DOI: 10.1007/s11094-020-02163-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
11
|
Hlozek J, Ravenscroft N, Kuttel MM. Effects of Glucosylation and O-Acetylation on the Conformation of Shigella flexneri Serogroup 2 O-Antigen Vaccine Targets. J Phys Chem B 2020; 124:2806-2814. [PMID: 32204588 DOI: 10.1021/acs.jpcb.0c01595] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Shigellosis is an enteric disease with high morbidity and mortality, particularly in developing countries. There is currently no licensed vaccine available. Most infection is caused by Shigella flexneri, of which 30 serotypes have been recognized based on O-antigen polysaccharide structure. Almost all S. flexneri serotypes share the same repeating unit backbone (serotype Y), with varying glucosylation, O-acetylation and phosphorylation. The O-antigen is the primary vaccine target; the vaccine valency (and hence cost) can be reduced by cross-protection. Our planned systematic conformational study of S. flexneri starts here with 2a, the dominant cause of infection globally. We employ microsecond molecular dynamics simulations to compare the conformation of the unsubstituted serotype Y backbone with the serogroup 2 O-antigens, to investigate the effect of glucosylation and O-acetylation (O-factor 9) on conformation. We find that serotype Y is highly flexible, whereas glucosylation in 2a restricts flexibility and induces C-curve conformations. Further, the glucose side-chains adopt two distinct conformations, corroborated by the antibody-bound crystal structure data. Additional substitution on O-3 of rhamnose A (whether O-acetylation in 2a or glucosylation in 2b) induces helical conformations. Our results suggest that the O-3-acetylated 2a antigen will elicit cross-protection against 2b, as well as other serotypes containing O-factor 9.
Collapse
Affiliation(s)
- Jason Hlozek
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Neil Ravenscroft
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Michelle M Kuttel
- Department of Computer Science, University of Cape Town, Rondebosch 7701, South Africa
| |
Collapse
|
12
|
Barel LA, Mulard LA. Classical and novel strategies to develop a Shigella glycoconjugate vaccine: from concept to efficacy in human. Hum Vaccin Immunother 2020; 15:1338-1356. [PMID: 31158047 PMCID: PMC6663142 DOI: 10.1080/21645515.2019.1606972] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Shigella are gram-negative bacteria that cause severe diarrhea and dysentery, with a high level of antimicrobial resistance. Disease-induced protection against reinfection in Shigella-endemic areas provides convincing evidence on the feasibility of a vaccine and on the importance of Shigella lipopolysaccharides as targets of the host humoral protective immune response against disease. This article provides an overview of the original and current strategies toward the development of a Shigella glycan-protein conjugate vaccine that would cover the most commonly detected strains. Going beyond pioneering “lattice”-type polysaccharide-protein conjugates, progress, and challenges are addressed with focus on promising alternatives, which have reached phases I and II clinical trial. Glycoengineered bioconjugates and “sun”-type conjugates featuring well-defined synthetic carbohydrate antigens are discussed with insights on the molecular parameters governing the rational design of a cost-effective glycoconjugate vaccine efficacious in preventing diseases caused by Shigella in the most at risk populations, young children living in endemic areas.
Collapse
Affiliation(s)
- Louis-Antoine Barel
- a Chemistry of Biomolecules Unit, Department of Structural Biology and Chemistry , Institut Pasteur, UMR3523, CNRS , Paris , France.,b Université Paris Descartes , Paris , France
| | - Laurence A Mulard
- a Chemistry of Biomolecules Unit, Department of Structural Biology and Chemistry , Institut Pasteur, UMR3523, CNRS , Paris , France
| |
Collapse
|
13
|
Parajuli P, Deimel LP, Verma NK. Genome Analysis of Shigella flexneri Serotype 3b Strain SFL1520 Reveals Significant Horizontal Gene Acquisitions Including a Multidrug Resistance Cassette. Genome Biol Evol 2019; 11:776-785. [PMID: 30715343 PMCID: PMC6424224 DOI: 10.1093/gbe/evz026] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/29/2019] [Indexed: 11/23/2022] Open
Abstract
Shigella flexneri is a major etiological agent of shigellosis in developing countries, primarily occurring in children under 5 years of age. We have sequenced, for the first time, the complete genome of S. flexneri serotype 3b (strain SFL1520). We used a hybrid sequencing method––both long-read MinION Flow (Oxford Nanopore Technologies) and short-read MiSeq (Illumina) sequencing to generate a high-quality reference genome. The SFL1520 chromosome was found to be ∼4.58 Mb long, with 4,729 coding sequences. Despite sharing a substantial number of genes with other publicly available S. flexneri genomes (2,803), the SFL1520 strain contains 1,926 accessory genes. The phage-related genes accounted for 8% of the SFL1520 genome, including remnants of the Sf6 bacteriophage with an intact O-acetyltransferase gene specific to serotype 3b. The SFL1520 chromosome was also found to contain a multiple-antibiotic resistance cassette conferring resistance to ampicillin, chloramphenicol, streptomycin, and tetracycline, which was potentially acquired from a plasmid via transposases. The phylogenetic analysis based on core genes showed a high level of similarity of SFL1520 with other S. flexneri serotypes; however, there were marked differences in the accessory genes of SFL1520. In particular, a large number of unique genes were identified in SFL1520 suggesting significant horizontal gene acquisition in a relatively short time period. The major virulence traits of SFL1520 (such as serotype conversion and antimicrobial resistance) were associated with horizontal gene acquisitions highlighting the role of horizontal gene transfer in S. flexneri diversity and evolution.
Collapse
Affiliation(s)
- Pawan Parajuli
- Division of Biomedical Science and Biochemistry, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Lachlan P Deimel
- Division of Biomedical Science and Biochemistry, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Naresh K Verma
- Division of Biomedical Science and Biochemistry, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| |
Collapse
|
14
|
Hu Z, Bongat White AF, Mulard LA. Efficient Iterative Synthesis of O-Acetylated Tri- to Pentadecasaccharides Related to the Lipopolysaccharide ofShigella flexneriType 3 a through Di- and Trisaccharide Glycosyl Donors. Chem Asian J 2017; 12:419-439. [DOI: 10.1002/asia.201600819] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Zhaoyu Hu
- Chemistry of Biomolecules; Institut Pasteur; 28 rue du Dr. Roux 75724 Paris Cedex 15 France
- CNRS UMR 3523; Institut Pasteur; 28 rue du Dr. Roux 75015 Paris France
| | - Aileen F. Bongat White
- Chemistry of Biomolecules; Institut Pasteur; 28 rue du Dr. Roux 75724 Paris Cedex 15 France
- CNRS UMR 3523; Institut Pasteur; 28 rue du Dr. Roux 75015 Paris France
- Dextra Laboratories Ltd.; Science and Technology Centre; Earley Gate Reading RG6 6BZ U. K
| | - Laurence A. Mulard
- Chemistry of Biomolecules; Institut Pasteur; 28 rue du Dr. Roux 75724 Paris Cedex 15 France
- CNRS UMR 3523; Institut Pasteur; 28 rue du Dr. Roux 75015 Paris France
| |
Collapse
|
15
|
Boutet J, Blasco P, Guerreiro C, Thouron F, Dartevelle S, Nato F, Cañada FJ, Ardá A, Phalipon A, Jiménez-Barbero J, Mulard LA. Detailed Investigation of the Immunodominant Role of O-Antigen Stoichiometric O-Acetylation as Revealed by Chemical Synthesis, Immunochemistry, Solution Conformation and STD-NMR Spectroscopy for Shigella flexneri 3a. Chemistry 2016; 22:10892-911. [PMID: 27376496 DOI: 10.1002/chem.201600567] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Indexed: 02/02/2023]
Abstract
Shigella flexneri 3a causes bacillary dysentery. Its O-antigen has the {2)-[α-d-Glcp-(1→3)]-α-l-Rhap-(1→2)-α-l-Rhap-(1→3)-[Ac→2]-α-l-Rhap-(1→3)-[Ac→6]≈40 % -β-d-GlcpNAc-(1→} ([(E)ABAc CAc D]) repeating unit, and the non-O-acetylated equivalent defines S. flexneri X. Propyl hepta-, octa-, and decasaccharides sharing the (E')A'BAc CD(E)A sequence, and their non-O-acetylated analogues were synthesized from a fully protected BAc CD(E)A allyl glycoside. The stepwise introduction of orthogonally protected mono- and disaccharide imidate donors was followed by a two-step deprotection process. Monoclonal antibody binding to twenty-six S. flexneri types 3a and X di- to decasaccharides was studied by an inhibition enzyme-linked immunosorbent assay (ELISA) and STD-NMR spectroscopy. Epitope mapping revealed that the 2C -acetate dominated the recognition by monoclonal IgG and IgM antibodies and that the BAc CD segment was essential for binding. The glucosyl side chain contributed to a lesser extent, albeit increasingly with the chain length. Moreover, tr-NOESY analysis also showed interaction but did not reveal any meaningful conformational change upon antibody binding.
Collapse
Affiliation(s)
- Julien Boutet
- Institut Pasteur, Unité de Chimie des Biomolécules, 28 rue du Dr. Roux, 75724, Paris Cedex 15, France.,CNRS UMR 3523, Institut Pasteur, 75015, Paris, France.,Université Paris Descartes, Institut Pasteur, 75015, Paris, France.,Present address for J.B.: Adisseo (France), Present address for P.B., Dept. of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691, Stockholm, Sweden
| | - Pilar Blasco
- Chemical and Physical Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain.,Present address for J.B.: Adisseo (France), Present address for P.B., Dept. of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691, Stockholm, Sweden
| | - Catherine Guerreiro
- Institut Pasteur, Unité de Chimie des Biomolécules, 28 rue du Dr. Roux, 75724, Paris Cedex 15, France.,CNRS UMR 3523, Institut Pasteur, 75015, Paris, France
| | - Françoise Thouron
- Institut Pasteur, Unité de Pathogénie Microbienne Moléculaire, 28 rue du Dr. Roux, 75015, Paris, France.,INSERM U1202, Institut Pasteur, 75015, Paris, France
| | - Sylvie Dartevelle
- Institut Pasteur, PF5, 28 rue du Dr. Roux, 75015, Paris, France.,CNRS UMR 3528, Institut Pasteur, 75015, Paris, France
| | - Farida Nato
- Institut Pasteur, PF5, 28 rue du Dr. Roux, 75015, Paris, France.,CNRS UMR 3528, Institut Pasteur, 75015, Paris, France
| | - F Javier Cañada
- Chemical and Physical Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Ana Ardá
- Chemical and Physical Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain.,Molecular Recognition & Host-Pathogen Interactions Program, CIC bioGUNE, Bizkaia Technological Park, Building 801A, 48160, Derio, Spain
| | - Armelle Phalipon
- Institut Pasteur, Unité de Pathogénie Microbienne Moléculaire, 28 rue du Dr. Roux, 75015, Paris, France.,INSERM U1202, Institut Pasteur, 75015, Paris, France
| | - Jesús Jiménez-Barbero
- Chemical and Physical Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain. .,Molecular Recognition & Host-Pathogen Interactions Program, CIC bioGUNE, Bizkaia Technological Park, Building 801A, 48160, Derio, Spain. .,Ikerbasque, Basque Foundation for Science, Maria Lopez de Haro 3, 48013, Bilbao, Spain.
| | - Laurence A Mulard
- Institut Pasteur, Unité de Chimie des Biomolécules, 28 rue du Dr. Roux, 75724, Paris Cedex 15, France. .,CNRS UMR 3523, Institut Pasteur, 75015, Paris, France.
| |
Collapse
|
16
|
Gauthier C, Chassagne P, Theillet FX, Guerreiro C, Thouron F, Nato F, Delepierre M, Sansonetti PJ, Phalipon A, Mulard LA. Non-stoichiometric O-acetylation of Shigella flexneri 2a O-specific polysaccharide: synthesis and antigenicity. Org Biomol Chem 2016; 12:4218-32. [PMID: 24836582 DOI: 10.1039/c3ob42586j] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Synthetic functional mimics of the O-antigen from Shigella flexneri 2a are seen as promising vaccine components against endemic shigellosis. Herein, the influence of the polysaccharide non-stoichiometric di-O-acetylation on antigenicity is addressed for the first time. Three decasaccharides, representing relevant internal mono- and di-O-acetylation profiles of the O-antigen, were synthesized from a pivotal protected decasaccharide designed to tailor late stage site-selective O-acetylation. The latter was obtained via a convergent route involving the imidate glycosylation chemistry. Binding studies to five protective mIgGs showed that none of the acetates adds significantly to broad antibody recognition. Yet, one of the five antibodies had a unique pattern of binding. With IC50 in the micromolar to submicromolar range mIgG F22-4 exemplifies a remarkable tight binding antibody against diversely O-acetylated and non-O-acetylated fragments of a neutral polysaccharide of medical importance.
Collapse
Affiliation(s)
- Charles Gauthier
- Institut Pasteur, Chimie des Biomolécules, Dépt de Biologie Structurale et Chimie, 28 rue du Dr Roux, 75724 Paris Cedex 15, France.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Mann E, Ovchinnikova OG, King JD, Whitfield C. Bacteriophage-mediated Glucosylation Can Modify Lipopolysaccharide O-Antigens Synthesized by an ATP-binding Cassette (ABC) Transporter-dependent Assembly Mechanism. J Biol Chem 2015; 290:25561-70. [PMID: 26330553 DOI: 10.1074/jbc.m115.660803] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Indexed: 11/06/2022] Open
Abstract
Lysogenic bacteriophages may encode enzymes that modify the structures of lipopolysaccharide O-antigen glycans, altering the structure of the bacteriophage receptor and resulting in serotype conversion. This can enhance virulence and has implications for antigenic diversity and vaccine development. Side chain glucosylation is a common modification strategy found in a number of bacterial species. To date, glucosylation has only been observed in O-antigens synthesized by Wzy-dependent pathways, one of the two most prevalent O-antigen synthesis systems. Here we exploited a heterologous system to study the glucosylation potential of a model O-antigen produced in an ATP-binding cassette (ABC) transporter-dependent system. Although O-antigen production is cryptic in Escherichia coli K-12, because of a mutation in the synthesis genes, it possesses a prophage glucosylation cluster, which modifies the GlcNAc residue in an α-l-Rha-(1→3)-d-GlcNAc motif found in the original O16 antigen. Raoultella terrigena ATCC 33257 produces an O-antigen possessing the same disaccharide motif, but its assembly uses an ABC transporter-dependent system. E. coli harboring the R. terrigena O-antigen biosynthesis genes produced an O-antigen displaying reduced reactivity toward antisera raised against the native R. terrigena repeat structure, indicative of an altered chemical structure. Structural determination using NMR revealed the addition of glucose side chains to the repeat units. O-antigen modification was dependent on a functional ABC transporter, consistent with modification in the periplasm, and was eliminated by deletion of the glucosylation genes from the E. coli chromosome, restoring native level antisera sensitivity and structure. There are therefore no intrinsic mechanistic barriers for bacteriophage-mediated O-antigen glucosylation in ABC transporter-dependent pathways.
Collapse
Affiliation(s)
- Evan Mann
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Olga G Ovchinnikova
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Jerry D King
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Chris Whitfield
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| |
Collapse
|
18
|
Yuriev E, Ramsland PA. Carbohydrates in Cyberspace. Front Immunol 2015; 6:300. [PMID: 26113848 PMCID: PMC4462093 DOI: 10.3389/fimmu.2015.00300] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 05/26/2015] [Indexed: 11/13/2022] Open
Affiliation(s)
- Elizabeth Yuriev
- Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, VIC , Australia
| | - Paul A Ramsland
- Centre for Biomedical Research, Burnet Institute , Melbourne, VIC , Australia ; Department of Immunology, Alfred Medical Research and Education Precinct, Monash University , Melbourne, VIC , Australia ; Department of Surgery Austin Health, University of Melbourne , Heidelberg, VIC , Australia ; CHIRI Biosciences, School of Biomedical Sciences, Curtin University , Perth, WA , Australia
| |
Collapse
|
19
|
Ardá A, Canales A, Cañada FJ, Jiménez-Barbero J. Carbohydrate–Protein Interactions: A 3D View by NMR. CARBOHYDRATES IN DRUG DESIGN AND DISCOVERY 2015. [DOI: 10.1039/9781849739993-00001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
NMR spectroscopy is a key tool for carbohydrate research. In studies with complex oligosaccharides there are limits to the amount of relevant structural information provided by these observables due to problems of signal overlapping, strong coupling and/or the scarcity of the key NOE information. Thus, there is an increasing need for additional parameters with structural information, such as residual dipolar couplings (RDCs), paramagnetic relaxation enhancements (PREs) or pseudo contact shifts (PCSs). Carbohydrates are rather flexible molecules. Therefore, NMR observables do not always correlate with a single conformer but with an ensemble of low free-energy conformers that can be accessed by thermal fluctuations. Depending on the system under study, different NMR approaches can be followed to characterize protein–carbohydrate interactions: the standard methodologies can usually be classified as “ligand-based” or “receptor-based”. The selection of the proper methodology is usually determined by the size of the receptor, the dissociation constant of the complex (KD), the availability of the labelled protein (15N, 13C) and the access to soluble receptors at enough concentration for NMR measurements.
Collapse
Affiliation(s)
- Ana Ardá
- Chemical and Physical Biology, CIB-CSIC Ramiro de Maeztu 9 28040 Madrid Spain
| | - Angeles Canales
- Chemical and Physical Biology, CIB-CSIC Ramiro de Maeztu 9 28040 Madrid Spain
| | - F. Javier Cañada
- Chemical and Physical Biology, CIB-CSIC Ramiro de Maeztu 9 28040 Madrid Spain
| | - Jesús Jiménez-Barbero
- Chemical and Physical Biology, CIB-CSIC Ramiro de Maeztu 9 28040 Madrid Spain
- CIC bioGUNE, Parque Tecnológico de Bizkaia Edif. 801A-1 48160 Derio-Bizkaia Spain
- Ikerbasque, Basque Foundation for Science Bilbao Spain
| |
Collapse
|
20
|
Salamone S, Guerreiro C, Cambon E, André I, Remaud-Siméon M, Mulard LA. Programmed chemo-enzymatic synthesis of the oligosaccharide component of a carbohydrate-based antibacterial vaccine candidate. Chem Commun (Camb) 2015; 51:2581-4. [DOI: 10.1039/c4cc08805k] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The powerful chemo-enzymatic synthesis of the pentadecasaccharide hapten involved in the first synthetic carbohydrate-based vaccine candidate against endemic shigellosis is reported.
Collapse
Affiliation(s)
- Stéphane Salamone
- Institut Pasteur
- Unité de Chimie des Biomolécules
- 75724 Paris Cedex 15
- France
- CNRS UMR 3523
| | - Catherine Guerreiro
- Institut Pasteur
- Unité de Chimie des Biomolécules
- 75724 Paris Cedex 15
- France
- CNRS UMR 3523
| | | | | | | | - Laurence A. Mulard
- Institut Pasteur
- Unité de Chimie des Biomolécules
- 75724 Paris Cedex 15
- France
- CNRS UMR 3523
| |
Collapse
|
21
|
|
22
|
Dhara D, Kar RK, Bhunia A, Misra AK. Convergent Synthesis and Conformational Analysis of the Hexasaccharide Repeating Unit of theO-Antigen ofShigella flexneriSerotype 1d. European J Org Chem 2014. [DOI: 10.1002/ejoc.201402392] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
23
|
Kang Y, Barbirz S, Lipowsky R, Santer M. Conformational Diversity of O-Antigen Polysaccharides of the Gram-Negative Bacterium Shigella flexneri Serotype Y. J Phys Chem B 2014; 118:2523-34. [DOI: 10.1021/jp4111713] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Yu Kang
- Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Stefanie Barbirz
- Physikalische
Biochemie, Universität Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Reinhard Lipowsky
- Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Mark Santer
- Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| |
Collapse
|
24
|
Steele D, Riddle M, van de Verg L, Bourgeois L. Vaccines for enteric diseases: a meeting summary. Expert Rev Vaccines 2014; 11:407-9. [DOI: 10.1586/erv.12.9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
25
|
Berti F, Adamo R. Recent mechanistic insights on glycoconjugate vaccines and future perspectives. ACS Chem Biol 2013; 8:1653-63. [PMID: 23841819 DOI: 10.1021/cb400423g] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Vaccination is a key strategy for the control of various infectious diseases. Many pathogens, such as Streptococcus pneumoniae , Haemophilus influenzae type b (Hib), and Neisseria meningitidis produce on their surfaces dense and complex glycan structures, which represent an optimal target for eliciting carbohydrate specific antibodies able to confer protection against those bacteria. Glycoconjugates represent nowadays an important class of efficacious and safe commercial vaccines. It has been known for a long time that covalent linkage of poorly immunogenic carbohydrates to protein is fundamental to provide T cell epitopes for eliciting a memory response of the immune system against the saccharide. However, while the traditional mechanism of action of glycoconjugates has considered peptides generated from the carrier protein to be responsible of T cell help recruitment, only recently evidence of the active involvement of the carbohydrate part in determining the T cell help has been shown. In addition, zwitterionic polysaccharides have been proven to activate the adaptive immune system without further conjugation to protein. Progress in this interface area between chemistry and biology, in combination with novel synthetic and biosynthetic methods for the preparation of glycoconjugates, is opening new perspectives to clarify their mechanism of action and give new insights for the design of improved carbohydrate-based vaccines.
Collapse
Affiliation(s)
- Francesco Berti
- Novartis Vaccines and Diagnostics, Research Center, Via Fiorentina 1, 53100 Siena, Italy
| | - Roberto Adamo
- Novartis Vaccines and Diagnostics, Research Center, Via Fiorentina 1, 53100 Siena, Italy
| |
Collapse
|
26
|
Horizontally acquired glycosyltransferase operons drive salmonellae lipopolysaccharide diversity. PLoS Genet 2013; 9:e1003568. [PMID: 23818865 PMCID: PMC3688519 DOI: 10.1371/journal.pgen.1003568] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2013] [Accepted: 05/01/2013] [Indexed: 12/16/2022] Open
Abstract
The immunodominant lipopolysaccharide is a key antigenic factor for Gram-negative pathogens such as salmonellae where it plays key roles in host adaptation, virulence, immune evasion, and persistence. Variation in the lipopolysaccharide is also the major differentiating factor that is used to classify Salmonella into over 2600 serovars as part of the Kaufmann-White scheme. While lipopolysaccharide diversity is generally associated with sequence variation in the lipopolysaccharide biosynthesis operon, extraneous genetic factors such as those encoded by the glucosyltransferase (gtr) operons provide further structural heterogeneity by adding additional sugars onto the O-antigen component of the lipopolysaccharide. Here we identify and examine the O-antigen modifying glucosyltransferase genes from the genomes of Salmonella enterica and Salmonella bongori serovars. We show that Salmonella generally carries between 1 and 4 gtr operons that we have classified into 10 families on the basis of gtrC sequence with apparent O-antigen modification detected for five of these families. The gtr operons localize to bacteriophage-associated genomic regions and exhibit a dynamic evolutionary history driven by recombination and gene shuffling events leading to new gene combinations. Furthermore, evidence of Dam- and OxyR-dependent phase variation of gtr gene expression was identified within eight gtr families. Thus, as O-antigen modification generates significant intra- and inter-strain phenotypic diversity, gtr-mediated modification is fundamental in assessing Salmonella strain variability. This will inform appropriate vaccine and diagnostic approaches, in addition to contributing to our understanding of host-pathogen interactions. Bacterial pathogens frequently evolve mechanisms to vary the composition of their surface structures. The consequence is enhanced long-term survival by facilitating persistence and evasion of the host immune system. Salmonella sp., cause severe infections in a range of mammalian hosts and guard themselves with a protective coat, termed the O-antigen. Through genome sequence analyses we found that Salmonella have acquired an unprecedented repertoire of genetic sequences for modifying their O-antigen coat. There is strong evidence that these genetic factors have a dynamic evolutionary history and are spread through the bacterial population by bacteriophage. In addition to this genetic repertoire, we determined that Salmonella can and often do employ stochastic mechanisms for expression of these genetic factors. This means that O-antigen coat diversity can be generated within a Salmonella population that otherwise has a common genome. Our data significantly enhance our appreciation of the genetic and regulatory characteristics underpinning Salmonella O-antigen diversity. The role attributed to bacteriophage in generating this diversity highlights that Salmonella are acquiring an extensive repertoire of O-antigen modifying traits that may enhance the pathogen's ability to persist and cause disease in mammalian hosts. Such genetic traits may make useful markers for defining new epidemiological and diagnostic tools.
Collapse
|
27
|
Chassagne P, Fontana C, Guerreiro C, Gauthier C, Phalipon A, Widmalm G, Mulard LA. Structural Studies of theO-Acetyl-Containing O-Antigen from aShigella flexneriSerotype 6 Strain and Synthesis of Oligosaccharide Fragments Thereof. European J Org Chem 2013. [DOI: 10.1002/ejoc.201300180] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
28
|
Abstract
Renewed awareness of the substantial morbidity and mortality that Shigella infection causes among young children in developing countries, combined with technological innovations in vaccinology, has led to the development of novel vaccine strategies in the past 5 years. Along with advancement of classic vaccines in clinical trials and new sophisticated measurements of immunological responses, much new data has been produced, lending promise to the potential for production of safe and effective Shigella vaccines. Herein, we review the latest progress in Shigella vaccine development within the framework of persistent obstacles.
Collapse
|
29
|
Theillet FX, Frank M, Vulliez-Le Normand B, Simenel C, Hoos S, Chaffotte A, Bélot F, Guerreiro C, Nato F, Phalipon A, Mulard LA, Delepierre M. Dynamic aspects of antibody:oligosaccharide complexes characterized by molecular dynamics simulations and saturation transfer difference nuclear magnetic resonance. Glycobiology 2011; 21:1570-9. [PMID: 21610193 DOI: 10.1093/glycob/cwr059] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Carbohydrates are likely to maintain significant conformational flexibility in antibody (Ab):carbohydrate complexes. As demonstrated herein for the protective monoclonal Ab (mAb) F22-4 recognizing the Shigella flexneri 2a O-antigen (O-Ag) and numerous synthetic oligosaccharide fragments thereof, the combination of molecular dynamics simulations and nuclear magnetic resonance saturation transfer difference experiments, supported by physicochemical analysis, allows us to determine the binding epitope and its various contributions to affinity without using any modified oligosaccharides. Moreover, the methods used provide insights into ligand flexibility in the complex, thus enabling a better understanding of the Ab affinities observed for a representative set of synthetic O-Ag fragments. Additionally, these complementary pieces of information give evidence to the ability of the studied mAb to recognize internal as well as terminal epitopes of its cognate polysaccharide antigen. Hence, we show that an appropriate combination of computational and experimental methods provides a basis to explore carbohydrate functional mimicry and receptor binding. The strategy may facilitate the design of either ligands or carbohydrate recognition domains, according to needed improvements of the natural carbohydrate:receptor properties.
Collapse
|