1
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Micoli F, Romano MR, Carboni F, Adamo R, Berti F. Strengths and weaknesses of pneumococcal conjugate vaccines. Glycoconj J 2023; 40:135-148. [PMID: 36652051 PMCID: PMC10027807 DOI: 10.1007/s10719-023-10100-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 11/24/2022] [Accepted: 01/09/2023] [Indexed: 01/19/2023]
Abstract
Multivalent vaccines addressing an increasing number of Streptococcus pneumoniae types (7-, 10-, 13-, 15-, 20-valent) have been licensed over the last 22 years. The use of polysaccharide-protein conjugate vaccines has been pivotal in reducing the incidence of invasive pneumococcal disease despite the emergence of non-vaccine serotypes. Notwithstanding its undoubtable success, some weaknesses have called for continuous improvement of pneumococcal vaccination. For instance, despite their inclusion in pneumococcal conjugate vaccines, there are challenges associated with some serotypes. In particular, Streptococcus pneumoniae type 3 remains a major cause of invasive pneumococcal disease in several countries.Here a deep revision of the strengths and weaknesses of the licensed pneumococcal conjugate vaccines and other vaccine candidates currently in clinical development is reported.
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2
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Morelli L, Lay L, Santana-Mederos D, Valdes-Balbin Y, Verez Bencomo V, van Diepen A, Hokke CH, Chiodo F, Compostella F. Glycan Array Evaluation of Synthetic Epitopes between the Capsular Polysaccharides from Streptococcus pneumoniae 19F and 19A. ACS Chem Biol 2021; 16:1671-1679. [PMID: 34469105 PMCID: PMC8453487 DOI: 10.1021/acschembio.1c00347] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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Vaccination represents
the most effective way to prevent invasive
pneumococcal diseases. The glycoconjugate vaccines licensed so far
are obtained from capsular polysaccharides (CPSs) of the most virulent
serotypes. Protection is largely limited to the specific vaccine serotypes,
and the continuous need for broader coverage to control the outbreak
of emerging serotypes is pushing the development of new vaccine candidates.
Indeed, the development of efficacious vaccine formulation is complicated
by the high number of bacterial serotypes with different CPSs. In
this context, to simplify vaccine composition, we propose the design
of new saccharide fragments containing chemical structures shared
by different serotypes as cross-reactive and potentially cross-protective
common antigens. In particular, we focused on Streptococcus
pneumoniae (Sp) 19A and 19F. The CPS repeating units of Sp
19F and 19A are very similar and share a common structure, the disaccharide
ManNAc-β-(1→4)-Glc (A-B). Herein, we describe the synthesis
of a small library of compounds containing different combinations
of the common 19F/19A disaccharide. The six new compounds were tested
with a glycan array to evaluate their recognition by antibodies in
reference group 19 antisera and factor reference antisera (reacting
against 19F or 19A). The disaccharide A-B, phosphorylated at the upstream
end, emerged as a hit from the glycan array screening because it is
strongly recognized by the group 19 antisera and by the 19F and 19A
factor antisera, with similar intensity compared with the CPSs used
as controls. Our data give a strong indication that the phosphorylated
disaccharide A-B can be considered a common epitope among different
Sp 19 serotypes.
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Affiliation(s)
- Laura Morelli
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Via Saldini 50, 20133 Milano, Italy
| | - Luigi Lay
- Department of Chemistry, University of Milan, Via Golgi 19, 20133 Milano, Italy
| | | | | | | | - Angela van Diepen
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
| | - Cornelis H. Hokke
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
| | - Fabrizio Chiodo
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
- Italian National Research Council (CNR), Institute of Biomolecular Chemistry (ICB), Via Campi Flegrei 34, 80078 Pozzuoli, Italy
| | - Federica Compostella
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Via Saldini 50, 20133 Milano, Italy
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3
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Richardson NI, Kuttel MM, Michael FS, Cairns C, Cox AD, Ravenscroft N. Cross-reactivity of Haemophilus influenzae type a and b polysaccharides: molecular modeling and conjugate immunogenicity studies. Glycoconj J 2021; 38:735-746. [PMID: 34491462 DOI: 10.1007/s10719-021-10020-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 08/16/2021] [Accepted: 08/25/2021] [Indexed: 10/20/2022]
Abstract
Haemophilus influenzae is a leading cause of meningitis disease and mortality, particularly in young children. Since the introduction of a licensed conjugate vaccine (targeting the outer capsular polysaccharide) against the most prevalent serotype, Haemophilus influenzae serotype b, the epidemiology of the disease has changed and Haemophilus influenzae serotype a is on the rise, especially in Indigenous North American populations. Here we apply molecular modeling to explore the preferred conformations of the serotype a and b capsular polysaccharides as well as a modified hydrolysis resistant serotype b polysaccharide. Although both serotype b and the modified serotype b have similar random coil behavior, our simulations reveal some differences in the polysaccharide conformations and surfaces which may impact antibody cross-reactivity between these two antigens. Importantly, we find significant conformational differences between the serotype a and b polysaccharides, indicating a potential lack of cross-reactivity that is corroborated by immunological data showing little recognition or killing between heterologous serotypes. These findings support the current development of a serotype a conjugate vaccine.
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Affiliation(s)
- Nicole I Richardson
- 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
| | - Frank St Michael
- Vaccine and Emerging Infections Research, Human Health Therapeutics Research Centre, National Research Council, Ottawa, ON, K1A 0R6, Canada
| | - Chantelle Cairns
- Vaccine and Emerging Infections Research, Human Health Therapeutics Research Centre, National Research Council, Ottawa, ON, K1A 0R6, Canada
| | - Andrew D Cox
- Vaccine and Emerging Infections Research, Human Health Therapeutics Research Centre, National Research Council, Ottawa, ON, K1A 0R6, Canada
| | - Neil Ravenscroft
- Department of Chemistry, University of Cape Town, Rondebosch, 7701, South Africa.
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4
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Kuttel MM, Casadevall A, Oscarson S. Cryptococcus neoformans Capsular GXM Conformation and Epitope Presentation: A Molecular Modelling Study. Molecules 2020; 25:E2651. [PMID: 32517333 PMCID: PMC7321252 DOI: 10.3390/molecules25112651] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 06/01/2020] [Accepted: 06/04/2020] [Indexed: 12/31/2022] Open
Abstract
The pathogenic encapsulated Cryptococcus neoformans fungus causes serious disease in immunosuppressed hosts. The capsule, a key virulence factor, consists primarily of the glucuronoxylomannan polysaccharide (GXM) that varies in composition according to serotype. While GXM is a potential vaccine target, vaccine development has been confounded by the existence of epitopes that elicit non-protective antibodies. Although there is evidence for protective antibodies binding conformational epitopes, the secondary structure of GXM remains an unsolved problem. Here an array of molecular dynamics simulations reveal that the GXM mannan backbone is consistently extended and relatively inflexible in both C. neoformans serotypes A and D. Backbone substitution does not alter the secondary structure, but rather adds structural motifs: β DGlcA and β DXyl side chains decorate the mannan backbone in two hydrophillic fringes, with mannose-6-O-acetylation forming a hydrophobic ridge between them. This work provides mechanistic rationales for clinical observations-the importance of O-acetylation for antibody binding; the lack of binding of protective antibodies to short GXM fragments; the existence of epitopes that elicit non-protective antibodies; and the self-aggregation of GXM chains-indicating that molecular modelling can play a role in the rational design of conjugate vaccines.
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Affiliation(s)
- Michelle M. Kuttel
- Department of Computer Science, University of Cape Town, Cape Town 7701, South Africa
| | - Arturo Casadevall
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, 615 N Wolfe St Room E5132, Baltimore, MD 21205, USA;
| | - Stefan Oscarson
- Centre for Synthesis and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland;
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5
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Hlozek J, Ravenscroft N, Kuttel MM. Modeling the conformations of Neisseria meningitidis serogroup a CPS and a carba-analogue: Implications for vaccine development. Carbohydr Res 2019; 486:107838. [PMID: 31654945 DOI: 10.1016/j.carres.2019.107838] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 10/11/2019] [Accepted: 10/15/2019] [Indexed: 10/25/2022]
Abstract
Neisseria meningitidis is a major cause of bacterial meningitis worldwide, especially in Africa. The capsular polysaccharide is the main virulence factor and the target antigen for polysaccharide- and conjugate vaccines. Three tetravalent conjugate vaccines against serogroups A, C, Y and W have been licensed and the monovalent MenAfriVac® was introduced to address the high burden of serogroup A disease in the Meningitis Belt of sub-Saharan Africa. Three of these four vaccines are lyophilized due to the instability of the serogroup A antigen (MenA) in aqueous solution, resulting in a two vial presentation with concomitant additional costs for storage and distribution. Replacement of the saccharide ring oxygen with a methylene group is a promising approach to preparing a stable oligosaccharide MenA analogue (Carba-MenA) vaccine suitable for a liquid formulation. However, to be effective, Carba-MenA must elicit an immune response that is cross-reactive to the native MenA. Here we employ microsecond molecular dynamics simulations of ten repeats of MenA and Carba-MenA to establish that there are significant differences in the conformation and dynamics of these antigens in solution. Carba-MenA has a more random extended, conformation than MenA; MenA has a significant population of compact S-bend conformations that are absent in the analogue. We also find that the disaccharides are poor models of the conformational behaviour of longer chains. This information is relevant for the rational design of optimal analogues for conjugate vaccines.
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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.
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6
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González-Alemán R, Hernández-Castillo D, Caballero J, Montero-Cabrera LA. Quality Threshold Clustering of Molecular Dynamics: A Word of Caution. J Chem Inf Model 2019; 60:467-472. [PMID: 31532987 DOI: 10.1021/acs.jcim.9b00558] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Clustering Molecular Dynamics trajectories is a common analysis that allows grouping together similar conformations. Several algorithms have been designed and optimized to perform this routine task, and among them, Quality Threshold stands as a very attractive option. This algorithm guarantees that in retrieved clusters no pair of frames will have a similarity value greater than a specified threshold, and hence, a set of strongly correlated frames are obtained for each cluster. In this work, it is shown that various commonly used software implementations are flawed by confusing Quality Threshold with another simplistic well-known clustering algorithm published by Daura et al. (Daura, X.; van Gunsteren, W. F.; Jaun, B.; Mark, A. E.; Gademann, K.; Seebach, D. Peptide Folding: When Simulation Meets Experiment. Angew. Chemie Int. Ed. 1999, 38 (1/2), 236-240). Daura's algorithm does not impose any quality threshold for the frames contained in retrieved clusters, bringing unrelated structural configurations altogether. The advantages of using Quality Threshold whenever possible to explore Molecular Dynamic trajectories is exemplified. An in-house implementation of the original Quality Threshold algorithm has been developed in order to illustrate our comments, and its code is freely available for further use by the scientific community.
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Affiliation(s)
- Roy González-Alemán
- Laboratorio de Química Computacional y Teórica, Facultad de Química , Universidad de La Habana , 10400 La Habana , Cuba
| | - David Hernández-Castillo
- Laboratorio de Química Computacional y Teórica, Facultad de Química , Universidad de La Habana , 10400 La Habana , Cuba
| | - Julio Caballero
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería en Bioinformática , Universidad de Talca , 2 Norte 685, Casilla 721 , Talca , Chile
| | - Luis A Montero-Cabrera
- Laboratorio de Química Computacional y Teórica, Facultad de Química , Universidad de La Habana , 10400 La Habana , Cuba
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7
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Aytenfisu AH, Simon R, MacKerell AD. Impact of branching on the conformational heterogeneity of the lipopolysaccharide from Klebsiella pneumoniae: Implications for vaccine design. Carbohydr Res 2019; 475:39-47. [PMID: 30818097 DOI: 10.1016/j.carres.2019.02.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 02/09/2019] [Accepted: 02/13/2019] [Indexed: 02/08/2023]
Abstract
Resistance of Klebsiella pneumoniae (KP) to antibiotics has motivated the development of an efficacious KP human vaccine that would not be subject to antibiotic resistance. Klebsiella lipopolysaccharide (LPS) associated O polysaccharide (OPS) types have provoked broad interest as a vaccine antigen as there are only 4 that predominate worldwide (O1, O2a, O3, O5). Klebsiella O1 and O2 OPS are polygalactans that share a common D-Gal-I structure, for which a variant D-Gal-III was recently discovered. To understand the potential impact of this variability on antigenicity, a detailed molecular picture of the conformational differences associated with the addition of the D-Gal-III (1 → 4)-α-Galp branch is presented using enhanced-sampling molecular dynamics simulations. In D-Gal-I two major conformational states are observed while the presence of the 1 → 4 branch in D-Gal-III resulted in only a single dominant extended state. Stabilization of the more folded states in D-Gal-I is due to a O4-H⋯O2 hydrogen bond in the linear backbone that cannot occur in D-Gal-III as the O4 is in the Galp(1 → 4)Galp glycosidic linkage. The impact of branching in D-Gal-III also significantly decreases the accessibility of the monosaccharides in the linear backbone region of D-Gal-I, while the accessibility of the terminal D-Gal-II region of the OPS is not substantially altered. The present results suggest that a vaccine that targets both the D-Gal-I and D-Gal-III LPS can be developed by using D-Gal-III as the antigen combined with cross-reactivity experiments using the Gal-II polysaccharide to assure that this region of the LPS is the primary epitope of the antigen.
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Affiliation(s)
- Asaminew H Aytenfisu
- University of Maryland Computer-Aided Drug Design Center, Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD, 21201, United States
| | - Raphael Simon
- Center for Vaccine Development, Institute for Global Health, School of Medicine, University of Maryland, Baltimore, MD, 21201, United States
| | - Alexander D MacKerell
- University of Maryland Computer-Aided Drug Design Center, Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD, 21201, United States.
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8
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Kuttel MM, Ravenscroft N. Conformation and Cross-Protection in Group B Streptococcus Serotype III and Streptococcus pneumoniae Serotype 14: A Molecular Modeling Study. Pharmaceuticals (Basel) 2019; 12:ph12010028. [PMID: 30781826 PMCID: PMC6469160 DOI: 10.3390/ph12010028] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 02/01/2019] [Accepted: 02/09/2019] [Indexed: 01/06/2023] Open
Abstract
Although the branched capsular polysaccharides of Streptococcus agalactiae serotype III (GBSIII PS) and Streptococcus pneumoniae serotype 14 (Pn14 PS) differ only in the addition of a terminal sialic acid on the GBSIII PS side chains, these very similar polysaccharides are immunogenically distinct. Our simulations of GBSIII PS, Pn14 PS and the unbranched backbone polysaccharide provide a conformational rationale for the different antigenic epitopes identified for these PS. We find that side chains stabilize the proximal βdGlc(1→6)βdGlcNAc backbone linkage, restricting rotation and creating a well-defined conformational epitope at the branch point. This agrees with the glycotope structure recognized by an anti-GBSIII PS functional monoclonal antibody. We find the same dominant solution conformation for GBSIII and Pn14 PS: aside from the branch point, the backbone is very flexible with a “zig-zag” conformational habit, rather than the helix previously proposed for GBSIII PS. This suggests a common strategy for bacterial evasion of the host immune system: a flexible backbone that is less perceptible to the immune system, combined with conformationally-defined branch points presenting human-mimic epitopes. This work demonstrates how small structural features such as side chains can alter the conformation of a polysaccharide by restricting rotation around backbone linkages.
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Affiliation(s)
- Michelle M Kuttel
- Department of Computer Science, University of Cape Town, Cape Town 7701, South Africa.
| | - Neil Ravenscroft
- Department of Chemistry, University of Cape Town, Cape Town 7701, South Africa.
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9
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Morelli L, Fallarini S, Lombardi G, Colombo C, Lay L, Compostella F. Synthesis and biological evaluation of a trisaccharide repeating unit derivative of Streptococcus pneumoniae 19A capsular polysaccharide. Bioorg Med Chem 2018; 26:5682-5690. [PMID: 30449426 DOI: 10.1016/j.bmc.2018.10.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 10/10/2018] [Accepted: 10/18/2018] [Indexed: 02/05/2023]
Abstract
Streptococcus pneumoniae (SP) is a common human pathogen associated with a broad spectrum of diseases and it is still a leading cause of mortality and morbidity worldwide, especially in children. Moreover, SP is increasingly associated with drug resistance. Vaccination against the pathogen may thus represent an important strategy to overcome its threats to human health. In this context, revealing the molecular determinants of SP immunoreactivity may be relevant for the development of novel molecules with therapeutic perspectives as vaccine components. Serogroup 19 comprises the immune-cross reactive types 19F, 19A, 19B and 19C and it accounts for a high percentage of invasive pneumococcal diseases, mainly caused by serotypes 19F and 19A. Herein, we report the synthesis and biological evaluation of an aminopropyl derivative of the trisaccharide repeating unit of SP 19A. We compare two different synthetic strategies, based on different disconnections between the three monosaccharides which make up the final trisaccharide, to define the best approach for the preparation of the trisaccharide. Synthetic accessibility to the trisaccharide repeating unit lays the basis for the development of more complex biopolymer as well as saccharide conjugates. We also evaluate the binding affinity of the trisaccharide for anti-19A and anti-19F sera and discuss the relationship between the chemical properties of the trisaccharide unit and biological activity.
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Affiliation(s)
- Laura Morelli
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, Via Saldini 50, 20133 Milano, Italy
| | - Silvia Fallarini
- Dipartimento di Scienze del Farmaco, Università degli Studi del Piemonte Orientale, Largo Donegani 2, 28100 Novara, Italy
| | - Grazia Lombardi
- Dipartimento di Scienze del Farmaco, Università degli Studi del Piemonte Orientale, Largo Donegani 2, 28100 Novara, Italy
| | - Cinzia Colombo
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, 20133 Milano, Italy
| | - Luigi Lay
- Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, 20133 Milano, Italy
| | - Federica Compostella
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, Via Saldini 50, 20133 Milano, Italy.
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10
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Hlozek J, Kuttel MM, Ravenscroft N. Conformations of Neisseria meningitidis serogroup A and X polysaccharides: The effects of chain length and O-acetylation. Carbohydr Res 2018; 465:44-51. [PMID: 29940397 DOI: 10.1016/j.carres.2018.06.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 06/12/2018] [Accepted: 06/12/2018] [Indexed: 11/28/2022]
Abstract
Neisseria meningitidis is a major cause of bacterial meningitis worldwide especially in Africa. The capsular polysaccharide (CPS) is the main virulence factor and the target antigen for polysaccharide and conjugate vaccines. The high burden of serogroup A disease in the Meningitis Belt of sub-Saharan Africa led to the introduction of MenAfriVac®, which has successfully reduced the number of cases of group A disease. However, several outbreaks caused by other serogroups have been reported, including those due to serogroup X. The capsular polysaccharides of serogroups A and X are both homopolymers of amino sugars (α-D-ManNAc and α-D-GlcNAc) containing phosphodiester linkages at C-6 and C-4, respectively. The similarity of the primary structures of the two polysaccharides suggests that serogroup A vaccination may provide cross-protection against serogroup X disease. Molecular dynamics simulations of a series of serogroup A and X oligosaccharides reveal that the MenA CPS behaves as a flexible random coil which becomes less conformationally defined as the length increases, whereas serogroup X forms a more stable regular helical structure. The presence of the MenX helix is supported by NMR analysis; it has four residues per turn and becomes more stable as the chain length increases. Licensed MenA vaccines are largely O-acetylated at C-3: simulations show that these O-acetyl groups are highly solvent exposed and their presence favors more extended conformations compared to the more compact conformations of MenA without O-acetylation. These findings may have implications for the design of optimal conjugate vaccines.
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Affiliation(s)
- Jason Hlozek
- 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
| | - Neil Ravenscroft
- Department of Chemistry, University of Cape Town, Rondebosch, 7701, South Africa.
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11
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Genetic and structural elucidation of capsular polysaccharides from Streptococcus pneumoniae serotype 23A and 23B, and comparison to serotype 23F. Carbohydr Res 2017; 450:19-29. [DOI: 10.1016/j.carres.2017.08.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 08/11/2017] [Accepted: 08/14/2017] [Indexed: 11/17/2022]
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12
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Kuttel MM, Timol Z, Ravenscroft N. Cross-protection in Neisseria meningitidis serogroups Y and W polysaccharides: A comparative conformational analysis. Carbohydr Res 2017; 446-447:40-47. [DOI: 10.1016/j.carres.2017.05.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 05/05/2017] [Accepted: 05/05/2017] [Indexed: 10/19/2022]
Affiliation(s)
- Michelle M Kuttel
- Department of Computer Science, University of Cape Town, Cape Town, 7701, South Africa.
| | - Zaheer Timol
- Department of Chemistry, University of Cape Town, Cape Town, 7701, South Africa
| | - Neil Ravenscroft
- Department of Chemistry, University of Cape Town, Cape Town, 7701, South Africa
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13
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Kuttel MM, Cescutti P, Distefano M, Rizzo R. Fluorescence and NMR spectroscopy together with molecular simulations reveal amphiphilic characteristics of a Burkholderia biofilm exopolysaccharide. J Biol Chem 2017; 292:11034-11042. [PMID: 28468829 DOI: 10.1074/jbc.m117.785048] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 04/26/2017] [Indexed: 01/09/2023] Open
Abstract
Biofilms are a collective mode of bacterial life in which a self-produced matrix confines cells in close proximity to each other. Biofilms confer many advantages, including protection from chemicals (including antibiotics), entrapment of useful extracellular enzymes and nutrients, as well as opportunities for efficient recycling of molecules from dead cells. Biofilm matrices are aqueous gel-like structures composed of polysaccharides, proteins, and DNA stabilized by intermolecular interactions that may include non-polar connections. Recently, polysaccharides extracted from biofilms produced by species of the Burkholderia cepacia complex were shown to possess clusters of rhamnose, a 6-deoxy sugar with non-polar characteristics. Molecular dynamics simulations are well suited to characterizing the structure and dynamics of polysaccharides, but only relatively few such studies exist of their interaction with non-polar molecules. Here we report an investigation into the hydrophobic properties of the exopolysaccharide produced by Burkholderia multivorans strain C1576. Fluorescence experiments with two hydrophobic fluorescent probes established that this polysaccharide complexes hydrophobic species, and NMR experiments confirmed these interactions. Molecular simulations to model the hydrodynamics of the polysaccharide and the interaction with guest species revealed a very flexible, amphiphilic carbohydrate chain that has frequent dynamic interactions with apolar molecules; both hexane and a long-chain fatty acid belonging to the quorum-sensing system of B. multivorans were tested. A possible role of the non-polar domains of the exopolysaccharide in facilitating the diffusion of aliphatic species toward specific targets within the biofilm aqueous matrix is proposed.
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Affiliation(s)
- Michelle M Kuttel
- From the Department of Computer Science, University of Cape Town, Rondebosch 7701, South Africa and
| | - Paola Cescutti
- the Department of Life Sciences, University of Trieste, Via Licio Giorgieri 1, 34127 Trieste, Italy
| | - Marco Distefano
- the Department of Life Sciences, University of Trieste, Via Licio Giorgieri 1, 34127 Trieste, Italy
| | - Roberto Rizzo
- the Department of Life Sciences, University of Trieste, Via Licio Giorgieri 1, 34127 Trieste, Italy
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14
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Polysaccharide Capsule Composition of Pneumococcal Serotype 19A Subtypes Is Unaltered among Subtypes and Independent of the Nutritional Environment. Infect Immun 2016; 84:3152-3160. [PMID: 27550933 DOI: 10.1128/iai.00474-16] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/12/2016] [Indexed: 11/20/2022] Open
Abstract
Serotype 19A strains have emerged as a cause of invasive pneumococcal disease after the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7), and serotype 19A has now been included in the recent 13-valent vaccine (PCV13). Genetic analysis has revealed at least three different capsular serotype 19A subtypes, and nutritional environment-dependent variation of the 19A capsule structure has been reported. Pneumococcal vaccine effectiveness and serotyping accuracy might be impaired by structural differences in serotype 19A capsules. We therefore analyzed the distribution of 19A subtypes collected within a Swiss national surveillance program and determined capsule composition under different nutritional conditions with high-performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS), and nuclear magnetic resonance (NMR) spectroscopy. After the introduction of PCV7, a significant relative increase of subtype 19A-II and decrease of 19A-I occurred. Chemical analyses showed no difference in the composition as well as the linkage of 19A subtype capsular saccharides grown in defined and undefined growth media, which is consistent with a trisaccharide repeat unit composed of rhamnose, N-acetyl-mannosamine, and glucose. In summary, our study suggests that no structural variance dependent of the nutritional environment or the subtype exists. The serotype 19A subtype shift observed after the introduction of the PCV7 can therefore not be explained by selection of a capsule structure variant. However, capsule composition analysis of emerging 19A clones is recommended in cases where there is no other explanation for a selective advantage, such as antibiotic resistance or loss or acquisition of other virulence factors.
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15
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Kuttel MM, Ståhle J, Widmalm G. CarbBuilder: Software for building molecular models of complex oligo- and polysaccharide structures. J Comput Chem 2016; 37:2098-105. [DOI: 10.1002/jcc.24428] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 05/23/2016] [Accepted: 05/24/2016] [Indexed: 01/19/2023]
Affiliation(s)
- Michelle M. Kuttel
- Department of Computer Science; University of Cape Town; Cape Town 7701 South Africa
| | - Jonas Ståhle
- Department of Organic Chemistry, Arrhenius Laboratory; Stockholm University; Stockholm S-106 91 Sweden
| | - Göran Widmalm
- Department of Organic Chemistry, Arrhenius Laboratory; Stockholm University; Stockholm S-106 91 Sweden
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16
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Kang Y, Gohlke U, Engström O, Hamark C, Scheidt T, Kunstmann S, Heinemann U, Widmalm G, Santer M, Barbirz S. Bacteriophage Tailspikes and Bacterial O-Antigens as a Model System to Study Weak-Affinity Protein–Polysaccharide Interactions. J Am Chem Soc 2016; 138:9109-18. [DOI: 10.1021/jacs.6b00240] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Yu Kang
- Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Ulrich Gohlke
- Max-Delbrück-Centrum für Molekulare Medizin in der Helmholtz-Gemeinschaft, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Olof Engström
- Department
of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106
91 Stockholm, Sweden
| | - Christoffer Hamark
- Department
of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106
91 Stockholm, Sweden
| | - Tom Scheidt
- Physikalische
Biochemie, Universität Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Sonja Kunstmann
- Physikalische
Biochemie, Universität Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Udo Heinemann
- Max-Delbrück-Centrum für Molekulare Medizin in der Helmholtz-Gemeinschaft, Robert-Rössle-Str. 10, 13125 Berlin, Germany
- Institut
für Chemie und Biochemie, Freie Universität, Takustr. 6, 14195 Berlin, Germany
| | - Göran Widmalm
- Department
of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106
91 Stockholm, Sweden
| | - Mark Santer
- Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Stefanie Barbirz
- Physikalische
Biochemie, Universität Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
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