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Chateau A, Van der Verren SE, Remaut H, Fioravanti A. The Bacillus anthracis Cell Envelope: Composition, Physiological Role, and Clinical Relevance. Microorganisms 2020; 8:E1864. [PMID: 33255913 PMCID: PMC7759979 DOI: 10.3390/microorganisms8121864] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 11/23/2020] [Accepted: 11/24/2020] [Indexed: 12/31/2022] Open
Abstract
Anthrax is a highly resilient and deadly disease caused by the spore-forming bacterial pathogen Bacillus anthracis. The bacterium presents a complex and dynamic composition of its cell envelope, which changes in response to developmental and environmental conditions and host-dependent signals. Because of their easy to access extracellular locations, B. anthracis cell envelope components represent interesting targets for the identification and development of novel therapeutic and vaccine strategies. This review will focus on the novel insights regarding the composition, physiological role, and clinical relevance of B. anthracis cell envelope components.
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Affiliation(s)
- Alice Chateau
- Avignon Université, INRAE, UMR SQPOV, F-84914 Avignon, France;
| | - Sander E. Van der Verren
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, 1050 Brussels, Belgium; (S.E.V.d.V.); (H.R.)
- Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium
| | - Han Remaut
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, 1050 Brussels, Belgium; (S.E.V.d.V.); (H.R.)
- Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium
| | - Antonella Fioravanti
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, 1050 Brussels, Belgium; (S.E.V.d.V.); (H.R.)
- Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium
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2
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Manish M, Verma S, Kandari D, Kulshreshtha P, Singh S, Bhatnagar R. Anthrax prevention through vaccine and post-exposure therapy. Expert Opin Biol Ther 2020; 20:1405-1425. [DOI: 10.1080/14712598.2020.1801626] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Manish Manish
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Shashikala Verma
- Centre of Experimental Medicine & Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Divya Kandari
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Parul Kulshreshtha
- Department of Zoology, Shivaji College, University of Delhi, Delhi, India
| | - Samer Singh
- Centre of Experimental Medicine & Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
- Department of Microbial Biotechnology, Panjab University, Chandigarh, India
| | - Rakesh Bhatnagar
- Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
- Centre of Experimental Medicine & Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
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3
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Progress towards the Development of a NEAT Vaccine for Anthrax II: Immunogen Specificity and Alum Effectiveness in an Inhalational Model. Infect Immun 2020; 88:IAI.00082-20. [PMID: 32393506 DOI: 10.1128/iai.00082-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 04/23/2020] [Indexed: 12/24/2022] Open
Abstract
Bacillus anthracis is the causative agent of anthrax disease, presents with high mortality, and has been at the center of bioweapon efforts. The only currently U.S. FDA-approved vaccine to prevent anthrax in humans is anthrax vaccine adsorbed (AVA), which is protective in several animal models and induces neutralizing antibodies against protective antigen (PA), the cell-binding component of anthrax toxin. However, AVA requires a five-course regimen to induce immunity, along with an annual booster, and is composed of undefined culture supernatants from a PA-secreting strain. In addition, it appears to be ineffective against strains that lack anthrax toxin. Here, we investigated a vaccine formulation consisting of recombinant proteins from a surface-localized heme transport system containing near-iron transporter (NEAT) domains and its efficacy as a vaccine for anthrax disease. The cocktail of five NEAT domains was protective against a lethal challenge of inhaled bacillus spores at 3 and 28 weeks after vaccination. The reduction of the formulation to three NEATs (IsdX1, IsdX2, and Bslk) was as effective as a five-NEAT domain cocktail. The adjuvant alum, approved for use in humans, was as protective as Freund's Adjuvant, and protective vaccination correlated with increased anti-NEAT antibody reactivity and reduced bacterial levels in organs. Finally, the passive transfer of anti-NEAT antisera reduced mortality and disease severity, suggesting the protective component is comprised of antibodies. Collectively, these results provide evidence that a vaccine based upon recombinant NEAT proteins should be considered in the development of a next-generation anthrax vaccine.
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Bennett MR, Bombardi RG, Kose N, Parrish EH, Nagel MB, Petit RA, Read TD, Schey KL, Thomsen IP, Skaar EP, Crowe JE. Human mAbs to Staphylococcus aureus IsdA Provide Protection Through Both Heme-Blocking and Fc-Mediated Mechanisms. J Infect Dis 2020; 219:1264-1273. [PMID: 30496483 DOI: 10.1093/infdis/jiy635] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 11/17/2018] [Indexed: 11/13/2022] Open
Abstract
The nutrient metal iron plays a key role in the survival of microorganisms. The iron-regulated surface determinant (Isd) system scavenges heme-iron from the human host, enabling acquisition of iron in iron-deplete conditions in Staphylococcus aureus during infection. The cell surface receptors IsdB and IsdH bind hemoproteins and transfer heme to IsdA, the final surface protein before heme-iron is transported through the peptidoglycan. To define the human B-cell response to IsdA, we isolated human monoclonal antibodies (mAbs) specific to the surface Isd proteins and determined their mechanism of action. We describe the first isolation of fully human IsdA and IsdH mAbs, as well as cross-reactive Isd mAbs. Two of the identified IsdA mAbs worked in a murine septic model of infection to reduce bacterial burden during staphylococcal infection. Their protection was a result of both heme-blocking and Fc-mediated effector functions, underscoring the importance of targeting S. aureus using diverse mechanisms.
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Affiliation(s)
- Monique R Bennett
- Department of Pathology, Microbiology and Immunology, Nashville, Tennessee
| | - Robin G Bombardi
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Nurgun Kose
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Erica H Parrish
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Marcus B Nagel
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee
| | - Robert A Petit
- Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia
| | - Timothy D Read
- Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia
| | - Kevin L Schey
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee
| | - Isaac P Thomsen
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Eric P Skaar
- Department of Pathology, Microbiology and Immunology, Nashville, Tennessee.,Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee
| | - James E Crowe
- Department of Pathology, Microbiology and Immunology, Nashville, Tennessee.,Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee
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5
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Macdonald R, Mahoney BJ, Ellis-Guardiola K, Maresso A, Clubb RT. NMR experiments redefine the hemoglobin binding properties of bacterial NEAr-iron Transporter domains. Protein Sci 2019; 28:1513-1523. [PMID: 31120610 DOI: 10.1002/pro.3662] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 05/14/2019] [Indexed: 01/02/2023]
Abstract
Iron is a versatile metal cofactor that is used in a wide range of essential cellular processes. During infections, many bacterial pathogens acquire iron from human hemoglobin (Hb), which contains the majority of the body's total iron content in the form of heme (iron protoporphyrin IX). Clinically important Gram-positive bacterial pathogens scavenge heme using an array of secreted and cell-wall-associated receptors that contain NEAr-iron Transporter (NEAT) domains. Experimentally defining the Hb binding properties of NEAT domains has been challenging, limiting our understanding of their function in heme uptake. Here we show that solution-state NMR spectroscopy is a powerful tool to define the Hb binding properties of NEAT domains. The utility of this method is demonstrated using the NEAT domains from Bacillus anthracis and Listeria monocytogenes. Our results are compatible with the existence of at least two types of NEAT domains that are capable of interacting with either Hb or heme. These binding properties can be predicted from their primary sequences, with Hb- and heme-binding NEAT domains being distinguished by the presence of (F/Y)YH(Y/F) and S/YXXXY motifs, respectively. The results of this work should enable the functions of a wide range of NEAT domain containing proteins in pathogenic bacteria to be reliably predicted.
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Affiliation(s)
- Ramsay Macdonald
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California, 90095.,UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, Los Angeles, California, 90095
| | - Brendan J Mahoney
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California, 90095.,UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, Los Angeles, California, 90095
| | - Ken Ellis-Guardiola
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California, 90095.,UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, Los Angeles, California, 90095
| | - Anthony Maresso
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, 77030
| | - Robert T Clubb
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California, 90095.,UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, Los Angeles, California, 90095.,Molecular Biology Institute, University of California, Los Angeles, Los Angeles, California, 90095
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Clark J, Terwilliger A, Nguyen C, Green S, Nobles C, Maresso A. Heme catabolism in the causative agent of anthrax. Mol Microbiol 2019; 112:515-531. [PMID: 31063630 DOI: 10.1111/mmi.14270] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/02/2019] [Indexed: 12/23/2022]
Abstract
A challenge common to all bacterial pathogens is to acquire nutrients from hostile host environments. Iron is an important cofactor required for essential cellular processes such as DNA repair, energy production and redox balance. Within a mammalian host, most iron is sequestered within heme, which in turn is predominantly bound by hemoglobin. While little is understood about the mechanisms by which bacterial hemophores attain heme from host-hemoglobin, even less is known about intracellular heme processing. Bacillus anthracis, the causative agent of anthrax, displays a remarkable ability to grow in mammalian hosts. Hypothesizing this pathogen harbors robust ways to catabolize heme, we characterize two new intracellular heme-binding proteins that are distinct from the previously described IsdG heme monooxygenase. The first of these, HmoA, binds and degrades heme, is necessary for heme detoxification and facilitates growth on heme iron sources. The second protein, HmoB, binds and degrades heme too, but is not necessary for heme utilization or virulence. The loss of both HmoA and IsdG renders B. anthracis incapable of causing anthrax disease. The additional loss of HmoB in this background increases clearance of bacilli in lungs, which is consistent with this protein being important for survival in alveolar macrophages.
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Affiliation(s)
- Justin Clark
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Austen Terwilliger
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Chinh Nguyen
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Sabrina Green
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Chris Nobles
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Anthony Maresso
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
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Green MS, LeDuc J, Cohen D, Franz DR. Confronting the threat of bioterrorism: realities, challenges, and defensive strategies. THE LANCET. INFECTIOUS DISEASES 2018; 19:e2-e13. [PMID: 30340981 PMCID: PMC7106434 DOI: 10.1016/s1473-3099(18)30298-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 04/25/2018] [Accepted: 05/04/2018] [Indexed: 01/30/2023]
Abstract
Global terrorism is a rapidly growing threat to world security, and increases the risk of bioterrorism. In this Review, we discuss the potential threat of bioterrorism, agents that could be exploited, and recent developments in technologies and policy for detecting and controlling epidemics that have been initiated intentionally. The local and international response to infectious disease epidemics, such as the severe acute respiratory syndrome and west African Ebola virus epidemic, revealed serious shortcomings which bioterrorists might exploit when intentionally initiating an epidemic. Development of new vaccines and antimicrobial therapies remains a priority, including the need to expedite clinical trials using new methodologies. Better means to protect health-care workers operating in dangerous environments are also needed, particularly in areas with poor infrastructure. New and improved approaches should be developed for surveillance, early detection, response, effective isolation of patients, control of the movement of potentially infected people, and risk communication. Access to dangerous pathogens should be appropriately regulated, without reducing progress in the development of countermeasures. We conclude that preparedness for intentional outbreaks has the important added value of strengthening preparedness for natural epidemics, and vice versa.
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Affiliation(s)
- Manfred S Green
- School of Public Health, University of Haifa, Haifa, Israel.
| | - James LeDuc
- Galveston National Laboratory, University of Texas Medical Branch, Galveston, TX, USA
| | - Daniel Cohen
- School of Public Health, Tel Aviv University, Tel Aviv, Israel
| | - David R Franz
- College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
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Protection against inhalation anthrax by immunization with Salmonella enterica serovar Typhi Ty21a stably producing protective antigen of Bacillus anthracis. NPJ Vaccines 2017; 2:17. [PMID: 29263873 PMCID: PMC5627300 DOI: 10.1038/s41541-017-0018-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 04/28/2017] [Accepted: 05/11/2017] [Indexed: 02/08/2023] Open
Abstract
The national blueprint for biodefense concluded that the United States is underprepared for biological threats. The licensed anthrax vaccine absorbed vaccine, BioThrax, requires administration of at least 3–5 intramuscular doses. The anthrax vaccine absorbed vaccine consists of complex cell-free culture filtrates of a toxigenic Bacillus anthracis strain and causes tenderness at the injection site and significant adverse events. We integrated a codon-optimized, protective antigen gene of B. anthracis (plus extracellular secretion machinery), into the chromosome of the licensed, oral, live-attenuated typhoid fever vaccineTy21a to form Ty21a-PA-01 and demonstrated excellent expression of the gene encoding protective antigen. We produced the vaccine in a 10-L fermenter; foam-dried and vialed it, and characterized the dried product. The vaccine retained ~50% viability for 20 months at ambient temperature. Sera from animals immunized by the intraperitoneal route had high levels of anti-protective antigen antibodies by enzyme-linked immunosorbent assay and anthrax lethal toxin-neutralizing activity. Immunized mice were fully protected against intranasal challenge with ~5 LD50 of B. anthracis Sterne spores, and 70% (7/10) of vaccinated rabbits were protected against aerosol challenge with 200 LD50 of B. anthracis Ames spores. There was a significant correlation between protection and antibody levels determined by enzyme-linked immunosorbent assay and toxin-neutralizing activity. These data provide the foundation for achievement of our ultimate goal, which is to develop an oral anthrax vaccine that is stable at ambient temperatures and induces the rapid onset of durable, high-level protection after a 1-week immunization regimen. A vaccine candidate for anthrax infection shows promise for improving preparedness for a biological attack. Bacillus anthracis, the bacterium responsible for anthrax is a top-tier bioterrorism agent due to its high lethality and spore stability. The current FDA-approved anthrax vaccine and other vaccine candidates in development lack ease of preparation, have short shelf lives and adverse effects. B. Kim Lee Sim of Protein Potential LLC and her collaborators combined key B. anthracis genetic material into an existing typhoid vaccine. The vaccine vector possesses high stability, a strong safety record, and offers long-term protection after oral administration, which Sim’s group hopes to preserve in their candidate anthrax vaccine. The team showed that their hybrid vaccine conferred excellent protection in rabbits and a short vaccination regimen, and suggest further studies into its suitability for human vaccine studies.
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