1
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Evaluation of a Highly Efficient DNA Extraction Method for Bacillus anthracis Endospores. Microorganisms 2020; 8:microorganisms8050763. [PMID: 32443768 PMCID: PMC7285266 DOI: 10.3390/microorganisms8050763] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 05/15/2020] [Accepted: 05/18/2020] [Indexed: 11/19/2022] Open
Abstract
A variety of methods have been established in order to optimize the accessibility of DNA originating from Bacillusanthracis cells and endospores to facilitate highly sensitive molecular diagnostics. However, most endospore lysis techniques have not been evaluated in respect to their quantitative proficiencies. Here, we started by systematically assessing the efficiencies of 20 DNA extraction kits for vegetative B.anthracis cells. Of these, the Epicentre MasterPure kit gave the best DNA yields and quality suitable for further genomic analysis. Yet, none of the kits tested were able to extract reasonable quantities of DNA from cores of the endospores. Thus, we developed a mechanical endospore lysis protocol, facilitating the extraction of high-quality DNA. Transmission electron microscopy or the labelling of spores with the indicator dye propidium monoazide was utilized to assess lysis efficiency. Finally, the yield and quality of genomic spore DNA were quantified by PCR and they were found to be dependent on lysis matrix composition, instrumental parameters, and the method used for subsequent DNA purification. Our final standardized lysis and DNA extraction protocol allows for the quantitative detection of low levels (<50 CFU/mL) of B. anthracis endospores and it is suitable for direct quantification, even under resource-limited field conditions, where culturing is not an option.
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2
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Toxin-neutralizing antibodies elicited by naturally acquired cutaneous anthrax are elevated following severe disease and appear to target conformational epitopes. PLoS One 2020; 15:e0230782. [PMID: 32294093 PMCID: PMC7159215 DOI: 10.1371/journal.pone.0230782] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 03/09/2020] [Indexed: 01/03/2023] Open
Abstract
Understanding immune responses to native antigens in response to natural infections can lead to improved approaches to vaccination. This study sought to characterize the humoral immune response to anthrax toxin components, capsule and spore antigens in individuals (n = 46) from the Kayseri and Malatya regions of Turkey who had recovered from mild or severe forms of cutaneous anthrax infection, compared to regional healthy controls (n = 20). IgG antibodies to each toxin component, the poly-γ-D-glutamic acid capsule, the Bacillus collagen-like protein of anthracis (BclA) spore antigen, and the spore carbohydrate anthrose, were detected in the cases, with anthrax toxin neutralization and responses to Protective Antigen (PA) and Lethal Factor (LF) being higher following severe forms of the disease. Significant correlative relationships among responses to PA, LF, Edema Factor (EF) and capsule were observed among the cases. Though some regional control sera exhibited binding to a subset of the tested antigens, these samples did not neutralize anthrax toxins and lacked correlative relationships among antigen binding specificities observed in the cases. Comparison of serum binding to overlapping decapeptides covering the entire length of PA, LF and EF proteins in 26 cases compared to 8 regional controls revealed that anthrax toxin-neutralizing antibody responses elicited following natural cutaneous anthrax infection are directed to conformational epitopes. These studies support the concept of vaccination approaches that preserve conformational epitopes.
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3
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Rapid and Sensitive Multiplex Assay for the Detection of B. anthracis Spores from Environmental Samples. Pathogens 2020; 9:pathogens9030164. [PMID: 32120986 PMCID: PMC7157734 DOI: 10.3390/pathogens9030164] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 02/24/2020] [Accepted: 02/27/2020] [Indexed: 11/24/2022] Open
Abstract
Prompt and accurate detection of Bacillus anthracis spores is crucial in the event of intentional spore dissemination in order to reduce the number of expected casualties. Specific identification of these spores from environmental samples is both challenging and time-consuming. This is due to the high homology with other Bacillus species as well as the complex composition of environmental samples, which further impedes assay sensitivity. Previously, we showed that a short incubation of B.anthracis spores in a defined growth medium results in rapid germination, bacterial growth, and secretion of toxins, including protective antigen. In this work, we tested whether coupling the incubation process to a newly developed immune-assay will enable the detection of secreted toxins as markers for the presence of spores in environmental samples. The new immune assay is a flow cytometry-based multiplex that simultaneously detects a protective antigen, lethal factor, and edema factor. Our combined assay detects 1 × 103–1 × 104/mL spores after a 2 h incubation followed by the ~80 min immune-multiplex detection. Extending the incubation step to 5 h increased assay sensitivity to 1 × 102/mL spore. The protocol was validated in various environmental samples using attenuated or fully virulent B. anthracis spores. There was no substantial influence of contaminants derived from real environmental samples on the performance of the assay compared to clean samples, which allow the unequivocal detection of 3 × 103/mL and 3 × 102/mL spores following 2 and 5 hour’s incubation, respectively. Overall, we propose this method as a rapid, sensitive, and specific procedure for the identification of B. anthracis spores in environmental samples.
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4
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Zincke D, Norris MH, Kurmanov B, Hadfield TL, Blackburn JK. Nucleotide polymorphism assay for the identification of west African group Bacillus anthracis: a lineage lacking anthrose. BMC Microbiol 2020; 20:6. [PMID: 31910798 PMCID: PMC6947953 DOI: 10.1186/s12866-019-1693-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 12/24/2019] [Indexed: 11/14/2022] Open
Abstract
Background The exosporium of the anthrax-causing Bacillus anthracis endospores display a tetrasaccharide composed of three rhamnose residues and an unusual sugar termed anthrose. Anthrose is a proposed potential target for immunotherapy and for specific detection of B. anthracis. Although originally thought to be ubiquitous in B. anthracis, previous work identified an anthrose negative strain from a West African lineage isolated from cattle that could represent a vaccine escape mutant. These strains carry genes required for expression of the anthrose operon but premature stop codons resulting from an 8-bp insertion in BAS3320 (an amino-transferase) and a C/T substitution at position 892 of the BAS3321 (a glycosyltransferase) gene prevent anthrose expression. Various other single nucleotide polymorphisms (SNPs) have been identified throughout the operon and could be the basis for detection of anthrose-deficient strains. Results In this study, we evaluated rhAmp genotypic assays based on SNPs at positions 892 and 1352 of BAS3321 for detection and differentiation of anthrose negative (Ant−) West African strains. Discrimination of anthrose negative West African isolates was achieved with as low as 100 fg of DNA, whereas consistent genotyping of Sterne necessitated at least 1 pg of DNA. Conclusions Screening of a global panel of B. anthracis isolates showed anthrose-expressing alleles are prevalent worldwide whereas the anthrose-deficient phenotype is to date limited to West Africa. Our work also revealed a third, previously unreported anthrose genotype in which the operon is altogether missing from a Polish B. anthracis isolate.
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Affiliation(s)
- Diansy Zincke
- Spatial Epidemiology & Ecology Research Laboratory, Department of Geography, University of Florida, Gainesville, FL, USA.,Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - Michael H Norris
- Spatial Epidemiology & Ecology Research Laboratory, Department of Geography, University of Florida, Gainesville, FL, USA.,Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - Berzhan Kurmanov
- Spatial Epidemiology & Ecology Research Laboratory, Department of Geography, University of Florida, Gainesville, FL, USA.,Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - Ted L Hadfield
- Spatial Epidemiology & Ecology Research Laboratory, Department of Geography, University of Florida, Gainesville, FL, USA.,Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - Jason K Blackburn
- Spatial Epidemiology & Ecology Research Laboratory, Department of Geography, University of Florida, Gainesville, FL, USA. .,Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA.
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5
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Karimi F, Dabbagh S. Gel green fluorescence ssDNA aptasensor based on carbon nanotubes for detection of anthrax protective antigen. Int J Biol Macromol 2019; 140:842-850. [PMID: 31470050 DOI: 10.1016/j.ijbiomac.2019.08.219] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 08/16/2019] [Accepted: 08/26/2019] [Indexed: 01/09/2023]
Abstract
Bacillus anthracis, the causative agent of anthrax, is a harmful pathogen with potential ability as a biological weapon which persuades scientists to develop novel methods to detect anthrax from infected resources. In this study, a multi-walled carbon nanotube (MWCNTs)-based fluorescence aptasensor was fabricated to detect the recombinant protective antigen domain 4 (rPAD4) of Bacillus anthracis as the most important key factor in development of anthrax. First, PAD4 was recombinant expressed in E. coli and purified by Ni-NTA column. Second, the affinity of aptamer to rPAD4 was confirmed by ELAA assay. In aptasensor design, the aptamer was labeled with Gel Green and immobilized on MWCNTs. Upon the adsorption of labeled aptamer on MWCNTs, fluorescence emission was quenched. In contrast, by adding rPAD4 to hybridization reaction and incubation for 10 min, the fluorescence emission was significantly recovered to 85% compared to the control. Detection limit for the sensitivity and specificity of the aptasensor was determined 20 ng/ml and 62.5 ng/ml purified and unpurified rPAD4 protein, respectively. Also, applicability of aptasensor was showed in mouse serum sample. Finally, results indicated that nanosensor has the potential to be developed as a high-sensitive, cost-effective and fast-acting system for measuring of PA in anthrax diagnostic tests.
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Affiliation(s)
- Farrokh Karimi
- Department of Biotechnology, Faculty of Science, University of Maragheh, P.O. Box 55181-83111, Maragheh, Iran.
| | - Somayyeh Dabbagh
- Department of Biotechnology, Faculty of Science, University of Maragheh, P.O. Box 55181-83111, Maragheh, Iran
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6
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Khatun F, Stephenson RJ, Toth I. An Overview of Structural Features of Antibacterial Glycoconjugate Vaccines That Influence Their Immunogenicity. Chemistry 2017; 23:4233-4254. [PMID: 28097690 DOI: 10.1002/chem.201603599] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Indexed: 12/13/2022]
Abstract
Bacterial cell-surface-derived or mimicked carbohydrate moieties that act as protective antigens are used in the development of antibacterial glycoconjugate vaccines. The carbohydrate antigen must have a minimum length or size to maintain the conformational structure of the antigenic epitope(s). The presence or absence of O-acetate, phosphate, glycerol phosphate and pyruvate ketal plays a vital role in defining the immunogenicity of the carbohydrate antigen. The nature of the carrier protein, spacer and conjugation pattern used to develop the glycoconjugate vaccine also defines its overall spatial orientation which in turn affects its avidity and selectivity of interaction with the desired target(s). In addition, the ratio of carbohydrate to protein in glycoconjugate vaccines also makes an important contribution in determining the optimum immunological response. This Review article presents the importance of these variables in the development of antibacterial glycoconjugate vaccines and their effects on immune efficacy.
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Affiliation(s)
- Farjana Khatun
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, Australia
| | - Rachel J Stephenson
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, Australia
| | - Istvan Toth
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, Australia.,School of Pharmacy, Woolloongabba, The University of Queensland, QLD, Australia.,Institute for Molecular Bioscience, St. Lucia, The University of Queensland, QLD, Australia
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7
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The Exosporium Layer of Bacterial Spores: a Connection to the Environment and the Infected Host. Microbiol Mol Biol Rev 2016; 79:437-57. [PMID: 26512126 DOI: 10.1128/mmbr.00050-15] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Much of what we know regarding bacterial spore structure and function has been learned from studies of the genetically well-characterized bacterium Bacillus subtilis. Molecular aspects of spore structure, assembly, and function are well defined. However, certain bacteria produce spores with an outer spore layer, the exosporium, which is not present on B. subtilis spores. Our understanding of the composition and biological functions of the exosporium layer is much more limited than that of other aspects of the spore. Because the bacterial spore surface is important for the spore's interactions with the environment, as well as being the site of interaction of the spore with the host's innate immune system in the case of spore-forming bacterial pathogens, the exosporium is worthy of continued investigation. Recent exosporium studies have focused largely on members of the Bacillus cereus family, principally Bacillus anthracis and Bacillus cereus. Our understanding of the composition of the exosporium, the pathway of its assembly, and its role in spore biology is now coming into sharper focus. This review expands on a 2007 review of spore surface layers which provided an excellent conceptual framework of exosporium structure and function (A. O. Henriques and C. P. Moran, Jr., Annu Rev Microbiol 61:555-588, 2007, http://dx.doi.org/10.1146/annurev.micro.61.080706.093224). That review began a process of considering outer spore layers as an integrated, multilayered structure rather than simply regarding the outer spore components as independent parts.
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8
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Jakas A, Perc M, Suć J, Rodriguez MC, Cudic M, Cudic P. Synthesis of anthrose lipidic derivative as mimic of B. anthracis BclA glycoprotein for use in ELISA-like binding assays. J Carbohydr Chem 2016. [DOI: 10.1080/07328303.2016.1139124] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Andreja Jakas
- Division of Organic Chemistry and Biochemistry, Rudjer Bošković Institute, Zagreb, Croatia
| | - Milica Perc
- Division of Organic Chemistry and Biochemistry, Rudjer Bošković Institute, Zagreb, Croatia
| | - Josipa Suć
- Division of Organic Chemistry and Biochemistry, Rudjer Bošković Institute, Zagreb, Croatia
| | - Maria C. Rodriguez
- Department of Chemistry and Biochemistry, Florida Atlantic University, Boca Raton, FL, USA
| | - Mare Cudic
- Department of Chemistry and Biochemistry, Florida Atlantic University, Boca Raton, FL, USA
| | - Predrag Cudic
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, FL, USA
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9
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Maes E, Krzewinski F, Garenaux E, Lequette Y, Coddeville B, Trivelli X, Ronse A, Faille C, Guerardel Y. Glycosylation of BclA Glycoprotein from Bacillus cereus and Bacillus anthracis Exosporium Is Domain-specific. J Biol Chem 2016; 291:9666-77. [PMID: 26921321 DOI: 10.1074/jbc.m116.718171] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Indexed: 11/06/2022] Open
Abstract
The spores of the Bacillus cereus group (B. cereus, Bacillus anthracis, and Bacillus thuringiensis) are surrounded by a paracrystalline flexible yet resistant layer called exosporium that plays a major role in spore adhesion and virulence. The major constituent of its hairlike surface, the trimerized glycoprotein BclA, is attached to the basal layer through an N-terminal domain. It is then followed by a repetitive collagen-like neck bearing a globular head (C-terminal domain) that promotes glycoprotein trimerization. The collagen-like region of B. anthracis is known to be densely substituted by unusual O-glycans that may be used for developing species-specific diagnostics of B. anthracis spores and thus targeted therapeutic interventions. In the present study, we have explored the species and domain specificity of BclA glycosylation within the B. cereus group. First, we have established that the collagen-like regions of both B. anthracis and B. cereus are similarly substituted by short O-glycans that bear the species-specific deoxyhexose residues anthrose and the newly observed cereose, respectively. Second we have discovered that the C-terminal globular domains of BclA from both species are substituted by polysaccharide-like O-linked glycans whose structures are also species-specific. The presence of large carbohydrate polymers covering the surface of Bacillus spores may have a profound impact on the way that spores regulate their interactions with biotic and abiotic surfaces and represents potential new diagnostic targets.
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Affiliation(s)
- Emmanuel Maes
- From the Université de Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France and
| | - Frederic Krzewinski
- From the Université de Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France and
| | - Estelle Garenaux
- From the Université de Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France and
| | | | - Bernadette Coddeville
- From the Université de Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France and
| | - Xavier Trivelli
- From the Université de Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France and
| | | | | | - Yann Guerardel
- From the Université de Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France and
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10
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Broecker F, Anish C, Seeberger PH. Generation of Monoclonal Antibodies against Defined Oligosaccharide Antigens. Methods Mol Biol 2015; 1331:57-80. [PMID: 26169735 DOI: 10.1007/978-1-4939-2874-3_5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Unique carbohydrate antigens are expressed on the surface of various pathogens, including bacteria, parasites, and viruses, and aberrant glycosylation is a frequent feature of cancer cells. Antibodies recognizing such carbohydrate antigens may be used for the specific detection of potentially harmful cells, immunohistochemistry, and diagnostic and therapeutic applications. The generation of specific and strongly binding antibodies against defined carbohydrate epitopes is challenging, since isolated carbohydrates often suffer from low purity, usually have limited immunogenicity, and induce antibodies of low affinity. We describe a protocol to generate highly affine monoclonal antibodies (mAbs) against pure and defined synthetic carbohydrate antigens. First, an oligosaccharide is covalently coupled to an immunogenic carrier protein to obtain a glycoconjugate. This glycoconjugate is used to raise oligosaccharide-specific antibodies in mice, and splenocytes are fused with myeloma cells to form hybridomas. Hybridoma clones producing oligosaccharide-specific mAbs are selected by glycan microarray screening. Selected clones are expanded and mAbs are purified from the cell culture supernatant. This protocol is suitable to procure carbohydrate-specific mAbs of high specificity, selectivity, and affinity that may be useful for a variety of biochemical and medical applications.
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Affiliation(s)
- Felix Broecker
- Department of BiomolecularSystems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
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11
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Stöckel S, Meisel S, Elschner M, Rösch P, Popp J. Identification of Bacillus anthracis via Raman Spectroscopy and Chemometric Approaches. Anal Chem 2012; 84:9873-80. [DOI: 10.1021/ac302250t] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- S. Stöckel
- Institute
of Physical Chemistry
and Abbe School of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
| | - S. Meisel
- Institute
of Physical Chemistry
and Abbe School of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
| | - M. Elschner
- Friedrich Loeffler Institut, Federal Research Institute for Animal Health, Institute
of Bacterial Infections and Zoonoses, Naumburger Straße 96a,
07743 Jena, Germany
| | - P. Rösch
- Institute
of Physical Chemistry
and Abbe School of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
| | - J. Popp
- Institute
of Physical Chemistry
and Abbe School of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
- Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745 Jena,
Germany
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12
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Milhomme O, Köhler SM, Ropartz D, Lesur D, Pilard S, Djedaïni-Pilard F, Beyer W, Grandjean C. Synthesis and immunochemical evaluation of a non-methylated disaccharide analogue of the anthrax tetrasaccharide. Org Biomol Chem 2012; 10:8524-32. [PMID: 23010801 DOI: 10.1039/c2ob26131f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Anthrax tetrasaccharide is an oligosaccharide expressed at the outermost surface of the Bacillus anthracis spores, featuring three rhamnoses and a rare sugar called anthrose. This motif has now been identified as a plausible component of future human vaccines against anthrax. We report herein the synthesis of a 2-O-demethylated-β-D-anthropyranosyl-(1→3)-α-L-rhamnopyranose disaccharide analogue of this tetrasaccharide from a cyclic sulfate intermediate. This disaccharide conjugated to BSA induces an anti-native tetrasaccharide IgG antibody response when administered in BALB/c mice. Moreover, induced sera bound to native B. anthracis endospores. These results suggest that the disaccharide analogue, easily amenable for a synthetic scale-up, could be used in a glycoconjugate antigen formulation.
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Affiliation(s)
- Ophélie Milhomme
- Laboratoire des Glucides, FRE CNRS 3517, Institut de Chimie de Picardie, Université de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens Cedex, France
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13
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Fast and sensitive detection of Bacillus anthracis spores by immunoassay. Appl Environ Microbiol 2012; 78:6491-8. [PMID: 22773632 DOI: 10.1128/aem.01282-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus anthracis is one of the most dangerous potential biological weapons, and it is essential to develop a rapid and simple method to detect B. anthracis spores in environmental samples. The immunoassay is a rapid and easy-to-use method for the detection of B. anthracis by means of antibodies directed against surface spore antigens. With this objective in view, we have produced a panel of monoclonal antibodies against B. anthracis and developed colorimetric and electrochemiluminescence (ECL) immunoassays. Using Meso Scale Discovery ECL technology, which is based on electrochemiluminescence (ECL) detection utilizing a sulfo-Tag label that emits light upon electrochemical stimulation (using a dedicated ECL plate reader, an electrical current is placed across the microplate with electrodes integrated into the bottom of the plate, resulting in a series of electrically induced reactions leading to a luminescent signal), a detection limit ranging between 0.3 × 10(3) and 10(3) CFU/ml (i.e., 30 to 100 spores per test), depending on the B. anthracis strain assayed, was achieved. In complex matrices (5 mg/ml of soil or simulated powder), the detection level (without any sample purification or concentration) was never altered more than 3-fold compared with the results obtained in phosphate-buffered saline.
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14
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Milhomme O, Dhénin SG, Djedaïni-Pilard F, Moreau V, Grandjean C. Synthetic studies toward the anthrax tetrasaccharide: alternative synthesis of this antigen. Carbohydr Res 2012; 356:115-31. [DOI: 10.1016/j.carres.2012.01.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Revised: 01/15/2012] [Accepted: 01/17/2012] [Indexed: 10/14/2022]
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15
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Rapid detection methods for Bacillus anthracis in environmental samples: a review. Appl Microbiol Biotechnol 2012; 93:1411-22. [DOI: 10.1007/s00253-011-3845-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 12/12/2011] [Accepted: 12/14/2011] [Indexed: 12/11/2022]
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16
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Li D, Truong TV, Bills TM, Holt BC, VanDerwerken DN, Williams JR, Acharya A, Robison RA, Tolley HD, Lee ML. GC/MS Method for Positive Detection of Bacillus anthracis Endospores. Anal Chem 2012; 84:1637-44. [DOI: 10.1021/ac202606x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dan Li
- Department
of Chemistry and
Biochemistry, Brigham Young University,
Provo, Utah 84602, United States
| | - Tai V. Truong
- Department
of Chemistry and
Biochemistry, Brigham Young University,
Provo, Utah 84602, United States
| | - Teri M. Bills
- Department of Microbiology and
Molecular Biology, Brigham Young University, Provo, Utah 84602, United States
| | - Brian C. Holt
- Department of Statistics, Brigham Young University, Provo, Utah 84602, United
States
| | | | - John R. Williams
- Department
of Chemistry and
Biochemistry, Brigham Young University,
Provo, Utah 84602, United States
| | - Abhilasha Acharya
- Department
of Chemistry and
Biochemistry, Brigham Young University,
Provo, Utah 84602, United States
| | - Richard A. Robison
- Department of Microbiology and
Molecular Biology, Brigham Young University, Provo, Utah 84602, United States
| | - H. Dennis Tolley
- Department of Statistics, Brigham Young University, Provo, Utah 84602, United
States
| | - Milton L. Lee
- Department
of Chemistry and
Biochemistry, Brigham Young University,
Provo, Utah 84602, United States
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17
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Milhomme O, John C, Djedaïni-Pilard F, Grandjean C. Access to antigens related to anthrose using pivotal cyclic sulfite/sulfate intermediates. J Org Chem 2011; 76:5985-98. [PMID: 21678952 DOI: 10.1021/jo200340q] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Anthrose is the upstream terminal unit of the tetrasaccharide side chain from a major glycoprotein of Bacillus anthracis exosporium and is part of important antigenic determinants. A novel entry to anthrose-containing antigens and precursors is described. The synthetic route, starting from D(+)-fucose, makes use of intermediates featuring a cyclic sulfite or sulfate function which serves successively as a protecting and a leaving group.
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Affiliation(s)
- Ophélie Milhomme
- Laboratoire des Glucides, UMR CNRS 6219, Institut de Chimie de Picardie, Université de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens Cedex, France
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18
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Concise synthesis of Bacillus anthracis exosporium tetrasaccharide via two-stage activation of allyl glycosyl donor strategy. Tetrahedron Lett 2011. [DOI: 10.1016/j.tetlet.2011.05.089] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Role played by exosporium glycoproteins in the surface properties of Bacillus cereus spores and in their adhesion to stainless steel. Appl Environ Microbiol 2011; 77:4905-11. [PMID: 21622795 DOI: 10.1128/aem.02872-10] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus cereus spores are surrounded by a loose-fitting layer called the exosporium, whose distal part is mainly formed from glycoproteins. The role played by the exosporium glycoproteins of B. cereus ATCC 14579 (BclA and ExsH) was investigated by considering hydrophobicity and charge, as well as the properties of spore adhesion to stainless steel. The absence of BclA increased both the isoelectric point (IEP) and hydrophobicity of whole spores while simultaneously reducing the interaction between spores and stainless steel. However, neither the hydrophobicity nor the charge associated with BclA could explain the differences in the adhesion properties. Conversely, ExsH, another exosporium glycoprotein, did not play a significant role in spore surface properties. The monosaccharide analysis of B. cereus ATCC 14579 showed different glycosylation patterns on ExsH and BclA. Moreover, two specific glycosyl residues, namely, 2-O-methyl-rhamnose (2-Me-Rha) and 2,4-O-methyl-rhamnose (2,4-Me-Rha), were attached to BclA, in addition to the glycosyl residues already reported in B. anthracis.
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Identification of an African Bacillus anthracis lineage that lacks expression of the spore surface-associated anthrose-containing oligosaccharide. J Bacteriol 2011; 193:3506-11. [PMID: 21571994 DOI: 10.1128/jb.00078-11] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The surfaces of Bacillus anthracis endospores expose a pentasaccharide containing the monosaccharide anthrose, which has been considered for use as a vaccine or target for specific detection of the spores. In this study B. anthracis strains isolated from cattle carcasses in African countries where anthrax is endemic were tested for their cross-reactivity with monoclonal antibodies (MAbs) specific for anthrose-containing oligosaccharides. Unexpectedly, none of the isolates collected in Chad, Cameroon, and Mali were recognized by the MAbs. Sequencing of the four-gene operon encoding anthrose biosynthetic enzymes revealed the presence of premature stop codons in the aminotransferase and glycosyltransferase genes in all isolates from Chad, Cameroon, and Mali. Both immunological and genetic findings suggest that the West African isolates are unable to produce anthrose. The anthrose-deficient strains from West Africa belong to a particular genetic lineage. Immunization of cattle in Chad with a locally produced vaccine based on anthrose-positive spores of the B. anthracis strain Sterne elicited an anti-carbohydrate IgG response specific for a synthetic anthrose-containing tetrasaccharide as demonstrated by glycan microarray analysis. Competition immunoblots with synthetic pentasaccharide derivatives suggested an immunodominant role of the anthrose-containing carbohydrate in cattle. In West Africa anthrax is highly endemic. Massive vaccination of livestock in this area has taken place over long periods of time using spores of the anthrose-positive vaccine strain Sterne. The spread of anthrose-deficient strains in this region may represent an escape strategy of B. anthracis.
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Antibody responses to a spore carbohydrate antigen as a marker of nonfatal inhalation anthrax in rhesus macaques. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2011; 18:743-8. [PMID: 21389148 DOI: 10.1128/cvi.00475-10] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The Bacillus anthracis exosporium protein BclA contains an O-linked antigenic tetrasaccharide whose terminal sugar is known as anthrose (J. M. Daubenspeck et al., J. Biol. Chem. 279:30945-30953, 2004). We hypothesized that serologic responses to anthrose may have diagnostic value in confirming exposure to aerosolized B. anthracis. We evaluated the serologic responses to a synthetic anthrose-containing trisaccharide (ATS) in a group of five rhesus macaques that survived inhalation anthrax following exposure to B. anthracis Ames spores. Two of five animals (RM2 and RM3) were treated with ciprofloxacin starting at 48 hours postexposure and two (RM4 and RM5) at 72 h postexposure; one animal (RM1) was untreated. Infection was confirmed by blood culture and detection of anthrax toxin lethal factor (LF) in plasma. Anti-ATS IgG responses were determined at 14, 21, 28, and 35 days postexposure, with preexposure serum as a control. All animals, irrespective of ciprofloxacin treatment, mounted a specific, measurable anti-ATS IgG response. The earliest detectable responses were on days 14 (RM1, RM2, and RM5), 21 (RM4), and 28 (RM3). Specificity of the anti-ATS responses was demonstrated by competitive-inhibition enzyme immunoassay (CIEIA), in which a 2-fold (wt/wt) excess of carbohydrate in a bovine serum albumin (BSA) conjugate of the oligosaccharide (ATS-BSA) effected >94% inhibition, whereas a structural analog lacking the 3-hydroxy-3-methyl-butyryl moiety at the C-4" of the anthrosyl residue had no inhibition activity. These data suggest that anti-ATS antibody responses may be used to identify aerosol exposure to B. anthracis spores. The anti-ATS antibody responses were detectable during administration of ciprofloxacin.
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Oberli MA, Tamborrini M, Tsai YH, Werz DB, Horlacher T, Adibekian A, Gauss D, Möller HM, Pluschke G, Seeberger PH. Molecular analysis of carbohydrate-antibody interactions: case study using a Bacillus anthracis tetrasaccharide. J Am Chem Soc 2010; 132:10239-41. [PMID: 20614885 DOI: 10.1021/ja104027w] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The process for selecting potent and effective carbohydrate antigens is not well-established. A combination of synthetic glycan microarray screening, surface plasmon resonance analysis, and saturation transfer difference NMR spectroscopy was used to dissect the antibody-binding surface of a carbohydrate antigen, revealing crucial binding elements with atomic-level detail. This analysis takes the first step toward uncovering the rules for structure-based design of carbohydrate antigens.
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Affiliation(s)
- Matthias A Oberli
- Department of Biomolecular Systems, Max-Planck Institute for Colloids and Interfaces, 14476 Potsdam, Germany
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Anthrax spore detection by a luminex assay based on monoclonal antibodies that recognize anthrose-containing oligosaccharides. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2010; 17:1446-51. [PMID: 20660139 DOI: 10.1128/cvi.00205-10] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The similarity of endospore surface antigens between bacteria of the Bacillus cereus group complicates the development of selective antibody-based anthrax detection systems. The surface of B. anthracis endospores exposes a tetrasaccharide containing the monosaccharide anthrose. Anti-tetrasaccharide monoclonal antibodies (MAbs) and anti-anthrose-rhamnose disaccharide MAbs were produced and tested for their fine specificities in a direct spore enzyme-linked immunosorbent assay (ELISA) with inactivated spores of a broad spectrum of B. anthracis strains and related species of the Bacillus genus. Although the two sets of MAbs had different fine specificities, all of them recognized the tested B. anthracis strains and showed only a limited cross-reactivity with two B. cereus strains. The MAbs were further tested for their ability to be implemented in a highly sensitive and specific bead-based Luminex assay. This assay detected spores from different B. anthracis strains and two cross-reactive B. cereus strains, correlating with the results obtained in direct spore ELISA. The Luminex assay (detection limit 10(3) to 10(4) spores per ml) was much more sensitive than the corresponding sandwich ELISA. Although not strictly specific for B. anthracis spores, the developed Luminex assay represents a useful first-line screening tool for the detection of B. anthracis spores.
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McPherson SA, Li M, Kearney JF, Turnbough CL. ExsB, an unusually highly phosphorylated protein required for the stable attachment of the exosporium of Bacillus anthracis. Mol Microbiol 2010; 76:1527-38. [PMID: 20444088 DOI: 10.1111/j.1365-2958.2010.07182.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The outermost layer of the Bacillus anthracis spore, the exosporium, is composed of a paracrystalline basal layer and an external hair-like nap. The nap is formed from a single collagen-like glycoprotein, while the basal layer contains many different proteins, including a 186-amino acid protein called ExsB. In this study, we discovered that ExsB is unusually highly phosphorylated, with at least 14 of its 19 threonine residues modified. The phosphorylated threonines are included in seven contiguous approximately 12-residue imperfect repeats, which presumably contain kinase recognition sequences. We demonstrated that a B. anthracis DeltaexsB mutant unable to synthesize ExsB produced spores with an exosporium that was readily sloughed, indicating that ExsB was required for stable exosporium attachment. This unstable exosporium also lacked the enzyme alanine racemase, which is normally tightly associated with the exosporium. Additionally, purified DeltaexsB spores lacking a visible exosporium were devoid of most exosporium proteins but, surprisingly, retained the putative exosporium proteins BxpC and CotB-1. Finally, we showed that transcription of the exsB gene occurred only during the late stages of sporulation, and we used an active and phosphorylated ExsB-EGFP fusion protein to monitor ExsB localization to wild-type and DeltabxpB mutant exosporia.
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Affiliation(s)
- Sylvia A McPherson
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Development of antibodies against anthrose tetrasaccharide for specific detection of Bacillus anthracis spores. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2009; 16:1728-37. [PMID: 19793896 DOI: 10.1128/cvi.00235-09] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Methods for the immunological detection of Bacillus anthracis in various environmental samples and the discrimination of B. anthracis from other members of the B. cereus group are not yet well established. To generate specific discriminating antibodies, we immunized rabbits, mice, and chickens with inactivated B. anthracis spores and, additionally, immunized rabbits and mice with the tetrasaccharide beta-Ant-(1-->3)-alpha-L-Rhap-(1-->3)-alpha-L-Rhap-(1-->2)-L-Rhap. It is a constituent of the exosporium glycoprotein BclA and contains the newly discovered sugar anthrose 2-O-methyl-4-(3-hydroxy-3-methylbutamido)-4,6-dideoxy-beta-D-glucose. The BclA protein is a major component of the exosporium of B. anthracis spores and is decorated by the tetrasaccharide indicated above. The anthrose-containing tetrasaccharide chain seems to be highly specific for B. anthracis, which makes it a key biomarker for the detection of these spores. The different immunizations led to anthrose-reactive polyclonal and monoclonal antibodies which were analyzed by various methods to characterize their ability to discriminate between B. anthracis and other Bacillus spp. Multiple applications, such as enzyme-linked immunosorbent assay, indirect immunofluorescence assay, and electron microscopy, revealed the specificities of the polyclonal and monoclonal antibodies generated for B. anthracis spore detection. All polyclonal antibodies were able to correctly identify the B. anthracis strains tested and showed only minimal cross-reactivities with other Bacillus strains. Moreover, the antibodies generated proved functional in a new capture assay for B. anthracis spores and could therefore be useful for the detection of spores in complex samples.
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Identification and classification of bcl genes and proteins of Bacillus cereus group organisms and their application in Bacillus anthracis detection and fingerprinting. Appl Environ Microbiol 2009; 75:7163-72. [PMID: 19767469 DOI: 10.1128/aem.01069-09] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The Bacillus cereus group includes three closely related species, B. anthracis, B. cereus, and B. thuringiensis, which form a highly homogeneous subdivision of the genus Bacillus. One of these species, B. anthracis, has been identified as one of the most probable bacterial biowarfare agents. Here, we evaluate the sequence and length polymorphisms of the Bacillus collagen-like protein bcl genes as a basis for B. anthracis detection and fingerprinting. Five genes, designated bclA to bclE, are present in B. anthracis strains. Examination of bclABCDE sequences identified polymorphisms in bclB alleles of the B. cereus group organisms. These sequence polymorphisms allowed specific detection of B. anthracis strains by PCR using both genomic DNA and purified Bacillus spores in reactions. By exploiting the length variation of the bcl alleles it was demonstrated that the combined bclABCDE PCR products generate markedly different fingerprints for the B. anthracis Ames and Sterne strains. Moreover, we predict that bclABCDE length polymorphism creates unique signatures for B. anthracis strains, which facilitates identification of strains with specificity and confidence. Thus, we present a new diagnostic concept for B. anthracis detection and fingerprinting, which can be used alone or in combination with previously established typing platforms.
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