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Fulurija A, Cunningham MW, Korotkova N, Masterson MY, Bansal GP, Baker MG, Cannon JW, Carapetis JR, Steer AC. Research opportunities for the primordial prevention of rheumatic fever and rheumatic heart disease-streptococcal vaccine development: a national heart, lung and blood institute workshop report. BMJ Glob Health 2023; 8:e013534. [PMID: 38164699 PMCID: PMC10729269 DOI: 10.1136/bmjgh-2023-013534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 11/01/2023] [Indexed: 01/03/2024] Open
Abstract
Streptococcus pyogenes, also known as group A streptococcus (StrepA), is a bacterium that causes a range of human diseases, including pharyngitis, impetigo, invasive infections, and post-infection immune sequelae such as rheumatic fever and rheumatic heart disease. StrepA infections cause some of the highest burden of disease and death in mostly young populations in low-resource settings. Despite decades of effort, there is still no licensed StrepA vaccine, which if developed, could be a cost-effective way to reduce the incidence of disease. Several challenges, including technical and regulatory hurdles, safety concerns and a lack of investment have hindered StrepA vaccine development. Barriers to developing a StrepA vaccine must be overcome in the future by prioritising key areas of research including greater understanding of StrepA immunobiology and autoimmunity risk, better animal models that mimic human disease, expanding the StrepA vaccine pipeline and supporting vaccine clinical trials. The development of a StrepA vaccine is a complex and challenging process that requires significant resources and investment. Given the global burden of StrepA infections and the potential for a vaccine to save lives and livelihoods, StrepA vaccine development is an area of research that deserves considerable support. This report summarises the findings of the Primordial Prevention Working Group-VAX, which was convened in November 2021 by the National Heart, Lung, and Blood Institute. The focus of this report is to identify research gaps within the current StrepA vaccine landscape and find opportunities and develop priorities to promote the rapid and successful advancement of StrepA vaccines.
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Affiliation(s)
- Alma Fulurija
- Wesfarmers Centre for Vaccines and Infectious Diseases, Telethon Kids Institute, Nedlands, Western Australia, Australia
- Centre for Child Health Research, The University of Western Australia, Perth, Western Australia, Australia
| | - Madeleine W Cunningham
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Natalia Korotkova
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky, Lexington, Kentucky, USA
| | - Mary Y Masterson
- Center for Translation Research and Implementation Science (CTRIS), National Heart Lung and Blood Institute, Bethesda, Maryland, USA
| | - Geetha P Bansal
- John E Fogarty International Center, Bethesda, Maryland, USA
| | - Michael G Baker
- Department of Public Health, University of Otago Wellington, Wellington, New Zealand
| | - Jeffrey W Cannon
- Centre for Child Health Research, The University of Western Australia, Perth, Western Australia, Australia
- Department of Global Health and Population, Harvard University T H Chan School of Public Health, Boston, Massachusetts, USA
| | - Jonathan R Carapetis
- Wesfarmers Centre for Vaccines and Infectious Diseases, Telethon Kids Institute, Nedlands, Western Australia, Australia
- Centre for Child Health Research, The University of Western Australia, Perth, Western Australia, Australia
- Department of Infectious Diseases, Perth Children's Hospital, Nedlands, Western Australia, Australia
| | - Andrew C Steer
- Infection, Immunity and Global Health, Murdoch Children's Research Institute, Parkville, Victoria, Australia
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2
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Azuar A, Shibu MA, Adilbish N, Marasini N, Hung H, Yang J, Luo Y, Khalil ZG, Capon RJ, Hussein WM, Toth I, Skwarczynski M. Poly(hydrophobic amino acid) Conjugates for the Delivery of Multiepitope Vaccine against Group A Streptococcus. Bioconjug Chem 2021; 32:2307-2317. [PMID: 34379392 DOI: 10.1021/acs.bioconjchem.1c00333] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Peptide-based vaccines are composed of small, defined, antigenic peptide epitopes. They are designed to induce well-controlled immune responses. Multiple epitopes are often employed in these vaccines to cover strain variability of a pathogen. However, peptide epitopes cannot stimulate adequate immune responses on their own and require an adjuvant (immune stimulant) and/or delivery system. Here, we designed and synthesized a multiepitope vaccine candidate against Group A Streptococcus (GAS) composed of several B-cell epitopes (J8, PL1, and 88/30) derived from GAS M-protein, universal PADRE T-helper cell epitope, and a polyleucine self-adjuvanting unit. The vaccine components were conjugated together (using mercapto-maleimide and azide-alkyne Huisgen cycloaddition reactions) or delivered as a mixture. The conjugated multiepitope vaccine candidate self-assembled into small nanoparticles and chain-like aggregated nanoparticles (CLANs) that were able to induce the production of J8-, PL1-, and 88/30-specific antibodies in mice. The multiepitope conjugate and the physical mixture of conjugates bearing the individual epitopes produced similar nanoparticles and induced comparable immune responses. Hence, simple physical mixing can replace complex chemical conjugation to produce multiepitope nanoparticles with equivalent morphology and immunological efficacy. This greatly simplifies vaccine production.
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Affiliation(s)
- Armira Azuar
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Mohini A Shibu
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Nomin Adilbish
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Nirmal Marasini
- School of Biomedical Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Hong Hung
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Jieru Yang
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Yacheng Luo
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Zeinab G Khalil
- Institute of Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Robert J Capon
- Institute of Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Waleed M Hussein
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Istvan Toth
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
- Institute of Molecular Bioscience, The University of Queensland, St. Lucia, Queensland 4072, Australia
- School of Pharmacy, The University of Queensland, Woolloongabba, Queensland 4102, Australia
| | - Mariusz Skwarczynski
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
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3
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Wang G, Zhao J, Zhao Y, Wang S, Feng S, Gu G. Immunogenicity Assessment of Different Segments and Domains of Group a Streptococcal C5a Peptidase and Their Application Potential as Carrier Protein for Glycoconjugate Vaccine Development. Vaccines (Basel) 2021; 9:vaccines9020139. [PMID: 33572233 PMCID: PMC7915350 DOI: 10.3390/vaccines9020139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 02/04/2021] [Accepted: 02/05/2021] [Indexed: 12/28/2022] Open
Abstract
Group A streptococcal C5a peptidase (ScpA) is a highly conserved surface virulence factor present on group A streptococcus (GAS) cell surfaces. It has attracted much more attention as a promising antigenic target for GAS vaccine development due to its high antigenicity to stimulate specific and immunoprotective antibodies. In this study, a series of segments of ScpA were rationally designed according to the functional domains described in its crystal structure, efficiently prepared and immunologically evaluated so as to assess their potential as antigens for the development of subunit vaccines. Immunological studies revealed that Fn, Fn2, and rsScpA193 proteins were promising antigen candidates worthy for further exploration. In addition, the potential of Fn and Fn2 as carrier proteins to formulate effective glycoconjugate vaccine was also investigated.
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Affiliation(s)
| | | | | | | | | | - Guofeng Gu
- Correspondence: ; Tel.: +86-532-5863-1408
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4
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Xu Z, Rivera-Hernandez T, Moyle PM. Development of an Enzyme-Mediated, Site-Specific Method to Conjugate Toll-Like Receptor 2 Agonists onto Protein Antigens: Toward a Broadly Protective, Four Component, Group A Streptococcal Self-Adjuvanting Lipoprotein-Fusion Combination Vaccine. ACS Infect Dis 2020; 6:1770-1782. [PMID: 32407620 DOI: 10.1021/acsinfecdis.0c00047] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Subunit vaccines composed of protein antigens covalently attached to Toll-like receptor (TLR) agonists elicit superior immune responses compared to mixtures of antigens and TLR agonists. Among different conjugation approaches, enzyme-mediated ligation is one of the few that provides an opportunity for the generation of homogeneous, molecularly defined products in which protein antigens are maintained with native structures, which is most critical to elicit protective immune responses upon vaccination. Four highly conserved protein antigens from Group A Streptococcus (GAS) have the potential to be safe and efficacious vaccine candidates. After a TLR2 agonist fibroblast-stimulating lipopeptide-1 (FSL-1) was successfully attached onto each antigen using sortase A and techniques for their purification were developed, a combination vaccine containing interleukin 8 (IL-8) protease (Streptococcus pyogenes cell envelope proteinase [SpyCEP]), Group A Streptococcal C5a peptidase (SCPA), anchorless virulence factor arginine deiminase (ADI), and trigger factor (TF)-TLR2 conjugates was produced. This combination was assessed for immunity in mice and compared with mixtures of the four antigens with FSL-1 or alum. High titer antigen-specific IgG antibodies were detected from all vaccine groups, with antibodies elicited from FSL-1 conjugates around 10-fold higher compared to the FSL-1 mixture group. Furthermore, the FSL-1 conjugates afforded a more balanced TH1/TH2 immune response than the alum-adjuvanted group, suggesting that this combination vaccine represents a promising candidate for the prevention of GAS diseases. Thus, we established a conjugation platform that allows for the production of defined, site-specific antigen-adjuvant conjugates, which maintain the native three-dimensional structure of antigens and can be potentially applied to a variety of protein antigens.
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Affiliation(s)
- Zhenghui Xu
- School of Pharmacy, The University of Queensland, 20 Cornwall Street, Woolloongabba, Queensland 4102, Australia
| | - Tania Rivera-Hernandez
- Australian Infectious Diseases Research Centre and School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
- Cátedras CONACYT - Unidad de Investigación Médica en Inmunoquímica, Hospital de Especialidades del Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City 06720, México
| | - Peter Michael Moyle
- School of Pharmacy, The University of Queensland, 20 Cornwall Street, Woolloongabba, Queensland 4102, Australia
- Australian Infectious Diseases Research Centre and School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
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5
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Wang S, Zhao Y, Wang G, Feng S, Guo Z, Gu G. Group A Streptococcus Cell Wall Oligosaccharide-Streptococcal C5a Peptidase Conjugates as Effective Antibacterial Vaccines. ACS Infect Dis 2020; 6:281-290. [PMID: 31872763 DOI: 10.1021/acsinfecdis.9b00347] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Group A streptococcus (GAS) is one of the common Gram-positive pathogenic bacteria accounting for a variety of infectious diseases. Currently, there is no commercial vaccine for GAS. To develop efficient GAS vaccines, synthetic tri-, hexa-, and nonasaccharides of a conserved group A carbohydrate (GAC) were conjugated with an inactive mutant of group A streptococcal C5a peptidase (ScpA), ScpA193, to create bivalent conjugate vaccines, which were compared with the corresponding CRM197 and TT conjugates. Systematic evaluations of these semisynthetic conjugates demonstrated that they could induce robust and comparable T-cell-dependent immune responses in mice. It was further disclosed that antibodies provoked by the ScpA193 conjugates, especially that of hexa- and nonasaccharides, could recognize and bind to GAS cells and mediate GAS opsonophagocytosis in vitro. In vivo evaluations of the hexa- and nonasaccharide-ScpA193 conjugates using a mouse model revealed that immunizing mice with especially the latter conjugate could effectively protect the animals from GAS challenges and GAS-induced pulmonary damage and significantly increase animal survival. Further in vitro studies suggested that the two ScpA193 conjugates could function through activating CD4+ T cells and promoting helper T cells (Th) to differentiate into antigen-specific Th1 and Th2 cells. In conclusion, the nonasaccharide-ScpA193 conjugate was identified as a particularly promising GAS vaccine candidate that is worthy of further investigation and development.
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Affiliation(s)
- Subo Wang
- National Glycoengineering Research Center and Shandong Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, 72 Binhai Road, Qingdao 266237, China
| | - Yisheng Zhao
- National Glycoengineering Research Center and Shandong Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, 72 Binhai Road, Qingdao 266237, China
| | - Guirong Wang
- National Glycoengineering Research Center and Shandong Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, 72 Binhai Road, Qingdao 266237, China
| | - Shaojie Feng
- National Glycoengineering Research Center and Shandong Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, 72 Binhai Road, Qingdao 266237, China
| | - Zhongwu Guo
- Department of Chemistry, University of Florida, 214 Leigh Hall, Gainesville, Florida 32611, United States
| | - Guofeng Gu
- National Glycoengineering Research Center and Shandong Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, 72 Binhai Road, Qingdao 266237, China
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6
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A Multicomponent Vaccine Provides Immunity against Local and Systemic Infections by Group A Streptococcus across Serotypes. mBio 2019; 10:mBio.02600-19. [PMID: 31772056 PMCID: PMC6879722 DOI: 10.1128/mbio.02600-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
GAS is among the most common human pathogens and causes a wide variety of diseases, likely more than any other microorganism. The diverse clinical manifestations of GAS may be attributable to its large repertoire of virulence factors that are selectively and synergistically involved in streptococcal pathogenesis. To date, GAS vaccines have not been successful due to multiple serotypes and postinfection sequelae associated with autoimmunity. In this study, five conserved virulence factors that are involved in GAS pathogenesis were used as a combined vaccine. Intranasal immunization with this vaccine induced humoral and cellular immune responses across GAS serotypes and protected against mucosal, systemic, and skin infections. The significance of this work is to demonstrate that the efficacy of GAS vaccines can be achieved by including multiple nonredundant critical virulence factors and inducing local and systemic immunity. The strategy also provides valuable insights for vaccine development against other pathogens. Group A streptococcus (GAS) species are responsible for a broad spectrum of human diseases, ranging from superficial to invasive infections, and are associated with autoimmune disorders. There is no commercial vaccine against GAS. The clinical manifestations of GAS infection may be attributable to the large repertoire of virulence factors used selectively in different types of GAS disease. Here, we selected five molecules, highly conserved among GAS serotypes, and involved in different pathogenic mechanisms, as a multicomponent vaccine, 5CP. Intranasal (i.n.) immunization with 5CP protected mice against both mucosal and systemic GAS infection across serotypes; the protection lasted at least 6 months. Immunization of mice with 5CP constrained skin lesion development and accelerated lesion recovery. Flow cytometry and enzyme-linked immunosorbent assay analyses revealed that 5CP induced Th17 and antibody responses locally and systemically; however, the Th17 response induced by 5CP resolved more quickly than that to GAS when challenge bacteria were cleared, suggesting that 5CP is less likely to cause autoimmune responses. These findings support that immunization through the i.n. route targeting multiple nonredundant virulence factors can induce immunity against different types of GAS disease and represents an alternative strategy for GAS vaccine development, with favorable efficacy, coverage, duration, and safety.
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7
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Davies MR, McIntyre L, Mutreja A, Lacey JA, Lees JA, Towers RJ, Duchêne S, Smeesters PR, Frost HR, Price DJ, Holden MTG, David S, Giffard PM, Worthing KA, Seale AC, Berkley JA, Harris SR, Rivera-Hernandez T, Berking O, Cork AJ, Torres RSLA, Lithgow T, Strugnell RA, Bergmann R, Nitsche-Schmitz P, Chhatwal GS, Bentley SD, Fraser JD, Moreland NJ, Carapetis JR, Steer AC, Parkhill J, Saul A, Williamson DA, Currie BJ, Tong SYC, Dougan G, Walker MJ. Atlas of group A streptococcal vaccine candidates compiled using large-scale comparative genomics. Nat Genet 2019; 51:1035-1043. [PMID: 31133745 DOI: 10.1038/s41588-019-0417-8] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 04/10/2019] [Indexed: 11/09/2022]
Abstract
Group A Streptococcus (GAS; Streptococcus pyogenes) is a bacterial pathogen for which a commercial vaccine for humans is not available. Employing the advantages of high-throughput DNA sequencing technology to vaccine design, we have analyzed 2,083 globally sampled GAS genomes. The global GAS population structure reveals extensive genomic heterogeneity driven by homologous recombination and overlaid with high levels of accessory gene plasticity. We identified the existence of more than 290 clinically associated genomic phylogroups across 22 countries, highlighting challenges in designing vaccines of global utility. To determine vaccine candidate coverage, we investigated all of the previously described GAS candidate antigens for gene carriage and gene sequence heterogeneity. Only 15 of 28 vaccine antigen candidates were found to have both low naturally occurring sequence variation and high (>99%) coverage across this diverse GAS population. This technological platform for vaccine coverage determination is equally applicable to prospective GAS vaccine antigens identified in future studies.
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Affiliation(s)
- Mark R Davies
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne and The Royal Melbourne Hospital, Melbourne, Victoria, Australia. .,The Wellcome Trust Sanger Institute, Hinxton, UK. .,School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia. .,Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia.
| | - Liam McIntyre
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne and The Royal Melbourne Hospital, Melbourne, Victoria, Australia
| | - Ankur Mutreja
- The Wellcome Trust Sanger Institute, Hinxton, UK.,GSK Vaccines Institute for Global Health, Siena, Italy
| | - Jake A Lacey
- Doherty Department, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne and The Royal Melbourne Hospital, Melbourne, Victoria, Australia
| | - John A Lees
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
| | - Rebecca J Towers
- Menzies School of Health Research, Darwin, Northern Territory, Australia
| | - Sebastián Duchêne
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne and The Royal Melbourne Hospital, Melbourne, Victoria, Australia.,Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Pierre R Smeesters
- Molecular Bacteriology Laboratory, Université Libre de Bruxelles, Brussels, Belgium.,Department of Pediatrics, Queen Fabiola Childrens University Hospital, Université Libre de Bruxelles, Brussels, Belgium.,Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
| | - Hannah R Frost
- Molecular Bacteriology Laboratory, Université Libre de Bruxelles, Brussels, Belgium.,Department of Pediatrics, Queen Fabiola Childrens University Hospital, Université Libre de Bruxelles, Brussels, Belgium.,Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
| | - David J Price
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia.,Victorian Infectious Diseases Reference Laboratory Epidemiology Unit, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne and The Royal Melbourne Hospital, Melbourne, Victoria, Australia
| | - Matthew T G Holden
- The Wellcome Trust Sanger Institute, Hinxton, UK.,School of Medicine, University of St Andrews, St Andrews, UK
| | - Sophia David
- The Wellcome Trust Sanger Institute, Hinxton, UK
| | - Philip M Giffard
- Menzies School of Health Research, Darwin, Northern Territory, Australia
| | - Kate A Worthing
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne and The Royal Melbourne Hospital, Melbourne, Victoria, Australia
| | | | - James A Berkley
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | | | - Tania Rivera-Hernandez
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia.,Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia
| | - Olga Berking
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia.,Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia
| | - Amanda J Cork
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia.,Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia
| | - Rosângela S L A Torres
- Laboratory of Bacteriology, Epidemiology Laboratory and Disease Control Division, Laboratório Central do Estado do Paraná, Curitiba, Brazil.,Department of Medicine, Universidade Positivo, Curitiba, Brazil
| | - Trevor Lithgow
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Richard A Strugnell
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne and The Royal Melbourne Hospital, Melbourne, Victoria, Australia
| | - Rene Bergmann
- Helmholtz Centre for Infection Research, Braunschweig, Germany
| | | | | | | | - John D Fraser
- Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Nicole J Moreland
- Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Jonathan R Carapetis
- Telethon Kids Institute, University of Western Australia and Perth Children's Hospital, Perth, Western Australia, Australia
| | - Andrew C Steer
- Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
| | | | - Allan Saul
- GSK Vaccines Institute for Global Health, Siena, Italy
| | - Deborah A Williamson
- Microbiological Diagnostic Unit Public Health Laboratory, Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne and The Royal Melbourne Hospital, Melbourne, Victoria, Australia
| | - Bart J Currie
- Menzies School of Health Research, Darwin, Northern Territory, Australia
| | - Steven Y C Tong
- Doherty Department, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne and The Royal Melbourne Hospital, Melbourne, Victoria, Australia.,Menzies School of Health Research, Darwin, Northern Territory, Australia.,Victorian Infectious Disease Service, The Royal Melbourne Hospital, Melbourne, Victoria, Australia
| | - Gordon Dougan
- The Wellcome Trust Sanger Institute, Hinxton, UK.,Department of Medicine, University of Cambridge, Cambridge, UK
| | - Mark J Walker
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia. .,Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia.
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8
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Abstract
The clinico-epidemiological features of diseases caused by group A streptococci (GAS) is presented through the lens of the ecology, population genetics, and evolution of the organism. The serological targets of three typing schemes (M, T, SOF) are themselves GAS cell surface proteins that have a myriad of virulence functions and a diverse array of structural forms. Horizontal gene transfer expands the GAS antigenic cell surface repertoire by generating numerous combinations of M, T, and SOF antigens. However, horizontal gene transfer of the serotype determinant genes is not unconstrained, and therein lies a genetic organization that may signify adaptations to a narrow ecological niche, such as the primary tissue reservoirs of the human host. Adaptations may be further shaped by selection pressures such as herd immunity. Understanding the molecular evolution of GAS on multiple levels-short, intermediate, and long term-sheds insight on mechanisms of host-pathogen interactions, the emergence and spread of new clones, rational vaccine design, and public health interventions.
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9
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Osowicki J, Azzopardi KI, McIntyre L, Rivera-Hernandez T, Ong CLY, Baker C, Gillen CM, Walker MJ, Smeesters PR, Davies MR, Steer AC. A Controlled Human Infection Model of Group A Streptococcus Pharyngitis: Which Strain and Why? mSphere 2019; 4:e00647-18. [PMID: 30760615 PMCID: PMC6374595 DOI: 10.1128/msphere.00647-18] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 01/16/2019] [Indexed: 01/23/2023] Open
Abstract
Group A Streptococcus (GAS) is a major cause of global infection-related morbidity and mortality. A modern controlled human infection model (CHIM) of GAS pharyngitis can accelerate vaccine development and pathogenesis research. A robust rationale for strain selection is central to meeting ethical, scientific, and regulatory requirements. Multifaceted characterization studies were done to compare a preferred candidate emm75 (M75) GAS strain to three other strains: an alternative candidate emm12 (M12) strain, an M1 strain used in 1970s pharyngitis CHIM studies (SS-496), and a representative (5448) of the globally disseminated M1T1 clone. A range of approaches were used to explore strain growth, adherence, invasion, delivery characteristics, short- and long-term viability, phylogeny, virulence factors, vaccine antigens, resistance to killing by human neutrophils, and lethality in a murine invasive model. The strains grew reliably in a medium without animal-derived components, were consistently transferred using a swab method simulating the CHIM protocol, remained viable at -80°C, and carried genes for most candidate vaccine antigens. Considering GAS molecular epidemiology, virulence factors, in vitro assays, and results from the murine model, the contemporary strains show a spectrum of virulence, with M75 appearing the least virulent and 5448 the most. The virulence profile of SS-496, used safely in 1970s CHIM studies, was similar to that of 5448 in the animal model and virulence gene carriage. The results of this multifaceted characterization confirm the M75 strain as an appropriate choice for initial deployment in the CHIM, with the aim of safely and successfully causing pharyngitis in healthy adult volunteers.IMPORTANCE GAS (Streptococcus pyogenes) is a leading global cause of infection-related morbidity and mortality. A modern CHIM of GAS pharyngitis could help to accelerate vaccine development and drive pathogenesis research. Challenge strain selection is critical to the safety and success of any CHIM and especially so for an organism such as GAS, with its wide strain diversity and potential to cause severe life-threatening acute infections (e.g., toxic shock syndrome and necrotizing fasciitis) and postinfectious complications (e.g., acute rheumatic fever, rheumatic heart disease, and acute poststreptococcal glomerulonephritis). In this paper, we outline the rationale for selecting an emm75 strain for initial use in a GAS pharyngitis CHIM in healthy adult volunteers, drawing on the findings of a broad characterization effort spanning molecular epidemiology, in vitro assays, whole-genome sequencing, and animal model studies.
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Affiliation(s)
- Joshua Osowicki
- Tropical Diseases, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
- Infectious Diseases Unit, Department of General Medicine, The Royal Children's Hospital Melbourne, Melbourne, Victoria, Australia
| | - Kristy I Azzopardi
- Tropical Diseases, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Liam McIntyre
- Department of Microbiology and Immunology, The University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Tania Rivera-Hernandez
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, St. Lucia, Queensland, Australia
| | - Cheryl-Lynn Y Ong
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, St. Lucia, Queensland, Australia
| | - Ciara Baker
- Tropical Diseases, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Christine M Gillen
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, St. Lucia, Queensland, Australia
| | - Mark J Walker
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, St. Lucia, Queensland, Australia
| | - Pierre R Smeesters
- Tropical Diseases, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
- Paediatric Department, Academic Children Hospital Queen Fabiola, Université Libre de Bruxelles, Brussels, Belgium
- Molecular Bacteriology Laboratory, Université Libre de Bruxelles, Brussels, Belgium
| | - Mark R Davies
- Department of Microbiology and Immunology, The University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Andrew C Steer
- Tropical Diseases, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
- Infectious Diseases Unit, Department of General Medicine, The Royal Children's Hospital Melbourne, Melbourne, Victoria, Australia
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10
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Ozberk V, Pandey M, Good MF. Contribution of cryptic epitopes in designing a group A streptococcal vaccine. Hum Vaccin Immunother 2018; 14:2034-2052. [PMID: 29873591 PMCID: PMC6150013 DOI: 10.1080/21645515.2018.1462427] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A successful vaccine needs to target multiple strains of an organism. Streptococcus pyogenes is an organism that utilizes antigenic strain variation as a successful defence mechanism to circumvent the host immune response. Despite numerous efforts, there is currently no vaccine available for this organism. Here we review and discuss the significant obstacles to vaccine development, with a focus on how cryptic epitopes may provide a strategy to circumvent the obstacles of antigenic variation.
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Affiliation(s)
- Victoria Ozberk
- a Griffith University, Institute for Glycomics , Gold Coast Campus, Queensland , Australia
| | - Manisha Pandey
- a Griffith University, Institute for Glycomics , Gold Coast Campus, Queensland , Australia
| | - Michael F Good
- a Griffith University, Institute for Glycomics , Gold Coast Campus, Queensland , Australia
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11
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Abstract
Streptococcus pyogenes, also known as Group A Streptococcus (GAS), is an important human bacterial pathogen that can cause invasive infections. Once it colonizes its exclusively human host, GAS needs to surmount numerous innate immune defense mechanisms, including opsonization by complement and consequent phagocytosis. Several strains of GAS bind to human-specific complement inhibitors, C4b-binding protein (C4BP) and/or Factor H (FH), to curtail complement C3 (a critical opsonin) deposition. This results in diminished activation of phagocytes and clearance of GAS that may lead to the host being unable to limit the infection. Herein we describe the course of GAS infection in three human complement inhibitor transgenic (tg) mouse models that examined each inhibitor (human C4BP or FH) alone, or the two inhibitors together (C4BPxFH or 'double' tg). GAS infection with strains that bound C4BP and FH resulted in enhanced mortality in each of the three transgenic mouse models compared to infection in wild type mice. In addition, GAS manifested increased virulence in C4BPxFH mice: higher organism burdens and greater elevations of pro-inflammatory cytokines and they died earlier than single transgenic or wt controls. The effects of hu-C4BP and hu-FH were specific for GAS strains that bound these inhibitors because strains that did not bind the inhibitors showed reduced virulence in the 'double' tg mice compared to strains that did bind; mortality was also similar in wild-type and C4BPxFH mice infected by non-binding GAS. Our findings emphasize the importance of binding of complement inhibitors to GAS that results in impaired opsonization and phagocytic killing, which translates to enhanced virulence in a humanized whole animal model. This novel hu-C4BPxFH tg model may prove invaluable in studies of GAS pathogenesis and for developing vaccines and therapeutics that rely on human complement activation for efficacy.
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12
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Correlates of Protection for M Protein-Based Vaccines against Group A Streptococcus. J Immunol Res 2015; 2015:167089. [PMID: 26101780 PMCID: PMC4458553 DOI: 10.1155/2015/167089] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 04/28/2015] [Accepted: 05/03/2015] [Indexed: 11/17/2022] Open
Abstract
Group A streptococcus (GAS) is known to cause a broad spectrum of illness, from pharyngitis and impetigo, to autoimmune sequelae such as rheumatic heart disease, and invasive diseases. It is a significant cause of infectious disease morbidity and mortality worldwide, but no efficacious vaccine is currently available. Progress in GAS vaccine development has been hindered by a number of obstacles, including a lack of standardization in immunoassays and the need to define human correlates of protection. In this review, we have examined the current immunoassays used in both GAS and other organisms, and explored the various challenges in their implementation in order to propose potential future directions to identify a correlate of protection and facilitate the development of M protein-based vaccines, which are currently the main GAS vaccine candidates.
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13
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Manganese homeostasis in group A Streptococcus is critical for resistance to oxidative stress and virulence. mBio 2015; 6:mBio.00278-15. [PMID: 25805729 PMCID: PMC4453566 DOI: 10.1128/mbio.00278-15] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Streptococcus pyogenes (group A Streptococcus [GAS]) is an obligate human pathogen responsible for a spectrum of human disease states. Metallobiology of human pathogens is revealing the fundamental role of metals in both nutritional immunity leading to pathogen starvation and metal poisoning of pathogens by innate immune cells. Spy0980 (MntE) is a paralog of the GAS zinc efflux pump CzcD. Through use of an isogenic mntE deletion mutant in the GAS serotype M1T1 strain 5448, we have elucidated that MntE is a manganese-specific efflux pump required for GAS virulence. The 5448ΔmntE mutant had significantly lower survival following infection of human neutrophils than did the 5448 wild type and the complemented mutant (5448ΔmntE::mntE). Manganese homeostasis may provide protection against oxidative stress, explaining the observed ex vivo reduction in virulence. In the presence of manganese and hydrogen peroxide, 5448ΔmntE mutant exhibits significantly lower survival than wild-type 5448 and the complemented mutant. We hypothesize that MntE, by maintaining homeostatic control of cytoplasmic manganese, ensures that the peroxide response repressor PerR is optimally poised to respond to hydrogen peroxide stress. Creation of a 5448ΔmntE-ΔperR double mutant rescued the oxidative stress resistance of the double mutant to wild-type levels in the presence of manganese and hydrogen peroxide. This work elucidates the mechanism for manganese toxicity within GAS and the crucial role of manganese homeostasis in maintaining GAS virulence. Manganese is traditionally viewed as a beneficial metal ion to bacteria, and it is also established that most bacteria can tolerate high concentrations of this transition metal. In this work, we show that in group A Streptococcus, mutation of the mntE locus, which encodes a transport protein of the cation diffusion facilitator (CDF) family, results in accumulation of manganese and sensitivity to this transition metal ion. The toxicity of manganese is indirect and is the result of a failure of the PerR regulator to respond to oxidative stress in the presence of high intracellular manganese concentrations. These results highlight the importance of MntE in manganese homeostasis and maintenance of an optimal manganese/iron ratio in GAS and the impact of manganese on resistance to oxidative stress and virulence.
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Henningham A, Döhrmann S, Nizet V, Cole JN. Mechanisms of group A Streptococcus resistance to reactive oxygen species. FEMS Microbiol Rev 2015; 39:488-508. [PMID: 25670736 PMCID: PMC4487405 DOI: 10.1093/femsre/fuu009] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 12/19/2014] [Indexed: 12/16/2022] Open
Abstract
Streptococcus pyogenes, also known as group A Streptococcus (GAS), is an exclusively human Gram-positive bacterial pathogen ranked among the ‘top 10’ causes of infection-related deaths worldwide. GAS commonly causes benign and self-limiting epithelial infections (pharyngitis and impetigo), and less frequent severe invasive diseases (bacteremia, toxic shock syndrome and necrotizing fasciitis). Annually, GAS causes 700 million infections, including 1.8 million invasive infections with a mortality rate of 25%. In order to establish an infection, GAS must counteract the oxidative stress conditions generated by the release of reactive oxygen species (ROS) at the infection site by host immune cells such as neutrophils and monocytes. ROS are the highly reactive and toxic byproducts of oxygen metabolism, including hydrogen peroxide (H2O2), superoxide anion (O2•−), hydroxyl radicals (OH•) and singlet oxygen (O2*), which can damage bacterial nucleic acids, proteins and cell membranes. This review summarizes the enzymatic and regulatory mechanisms utilized by GAS to thwart ROS and survive under conditions of oxidative stress. This review discusses the mechanisms utilized by the bacterial pathogen group A Streptococcus to detoxify reactive oxygen species and survive in the human host under conditions of oxidative stress.
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Affiliation(s)
- Anna Henningham
- Department of Pediatrics, University of California San Diego, La Jolla, CA 92093, USA The School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD 4072, Australia The Australian Infectious Diseases Research Centre, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Simon Döhrmann
- Department of Pediatrics, University of California San Diego, La Jolla, CA 92093, USA
| | - Victor Nizet
- Department of Pediatrics, University of California San Diego, La Jolla, CA 92093, USA Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA 92093, USA Rady Children's Hospital, San Diego, CA 92123, USA
| | - Jason N Cole
- Department of Pediatrics, University of California San Diego, La Jolla, CA 92093, USA The School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD 4072, Australia The Australian Infectious Diseases Research Centre, The University of Queensland, St Lucia, QLD 4072, Australia
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15
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Disease manifestations and pathogenic mechanisms of Group A Streptococcus. Clin Microbiol Rev 2014. [PMID: 24696436 DOI: 10.1128/cmr.00101-13)] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Streptococcus pyogenes, also known as group A Streptococcus (GAS), causes mild human infections such as pharyngitis and impetigo and serious infections such as necrotizing fasciitis and streptococcal toxic shock syndrome. Furthermore, repeated GAS infections may trigger autoimmune diseases, including acute poststreptococcal glomerulonephritis, acute rheumatic fever, and rheumatic heart disease. Combined, these diseases account for over half a million deaths per year globally. Genomic and molecular analyses have now characterized a large number of GAS virulence determinants, many of which exhibit overlap and redundancy in the processes of adhesion and colonization, innate immune resistance, and the capacity to facilitate tissue barrier degradation and spread within the human host. This improved understanding of the contribution of individual virulence determinants to the disease process has led to the formulation of models of GAS disease progression, which may lead to better treatment and intervention strategies. While GAS remains sensitive to all penicillins and cephalosporins, rising resistance to other antibiotics used in disease treatment is an increasing worldwide concern. Several GAS vaccine formulations that elicit protective immunity in animal models have shown promise in nonhuman primate and early-stage human trials. The development of a safe and efficacious commercial human vaccine for the prophylaxis of GAS disease remains a high priority.
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Walker MJ, Barnett TC, McArthur JD, Cole JN, Gillen CM, Henningham A, Sriprakash KS, Sanderson-Smith ML, Nizet V. Disease manifestations and pathogenic mechanisms of Group A Streptococcus. Clin Microbiol Rev 2014; 27:264-301. [PMID: 24696436 PMCID: PMC3993104 DOI: 10.1128/cmr.00101-13] [Citation(s) in RCA: 556] [Impact Index Per Article: 55.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Streptococcus pyogenes, also known as group A Streptococcus (GAS), causes mild human infections such as pharyngitis and impetigo and serious infections such as necrotizing fasciitis and streptococcal toxic shock syndrome. Furthermore, repeated GAS infections may trigger autoimmune diseases, including acute poststreptococcal glomerulonephritis, acute rheumatic fever, and rheumatic heart disease. Combined, these diseases account for over half a million deaths per year globally. Genomic and molecular analyses have now characterized a large number of GAS virulence determinants, many of which exhibit overlap and redundancy in the processes of adhesion and colonization, innate immune resistance, and the capacity to facilitate tissue barrier degradation and spread within the human host. This improved understanding of the contribution of individual virulence determinants to the disease process has led to the formulation of models of GAS disease progression, which may lead to better treatment and intervention strategies. While GAS remains sensitive to all penicillins and cephalosporins, rising resistance to other antibiotics used in disease treatment is an increasing worldwide concern. Several GAS vaccine formulations that elicit protective immunity in animal models have shown promise in nonhuman primate and early-stage human trials. The development of a safe and efficacious commercial human vaccine for the prophylaxis of GAS disease remains a high priority.
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Affiliation(s)
- Mark J. Walker
- School of Chemistry and Molecular Biosciences and the Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD, Australia
| | - Timothy C. Barnett
- School of Chemistry and Molecular Biosciences and the Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD, Australia
| | - Jason D. McArthur
- School of Biological Sciences and Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia
| | - Jason N. Cole
- School of Chemistry and Molecular Biosciences and the Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD, Australia
- Department of Pediatrics and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, USA
| | - Christine M. Gillen
- School of Chemistry and Molecular Biosciences and the Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD, Australia
| | - Anna Henningham
- School of Chemistry and Molecular Biosciences and the Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD, Australia
- Department of Pediatrics and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, USA
| | - K. S. Sriprakash
- QIMR Berghofer Medical Research Institute, Herston, Brisbane, QLD, Australia
| | - Martina L. Sanderson-Smith
- School of Biological Sciences and Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia
| | - Victor Nizet
- Department of Pediatrics and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, USA
- Rady Children's Hospital, San Diego, California, USA
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Structure-informed design of an enzymatically inactive vaccine component for group A Streptococcus. mBio 2013; 4:mBio.00509-13. [PMID: 23919999 PMCID: PMC3735194 DOI: 10.1128/mbio.00509-13] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Streptococcus pyogenes (group A Streptococcus [GAS]) causes ~700 million human infections/year, resulting in >500,000 deaths. There is no commercial GAS vaccine available. The GAS surface protein arginine deiminase (ADI) protects mice against a lethal challenge. ADI is an enzyme that converts arginine to citrulline and ammonia. Administration of a GAS vaccine preparation containing wild-type ADI, a protein with inherent enzymatic activity, may present a safety risk. In an approach intended to maximize the vaccine safety of GAS ADI, X-ray crystallography and structural immunogenic epitope mapping were used to inform vaccine design. This study aimed to knock out ADI enzyme activity without disrupting the three-dimensional structure or the recognition of immunogenic epitopes. We determined the crystal structure of ADI at 2.5 Å resolution and used it to select a number of amino acid residues for mutagenesis to alanine (D166, E220, H275, D277, and C401). Each mutant protein displayed abrogated activity, and three of the mutant proteins (those with the D166A, H275A, and D277A mutations) possessed a secondary structure and oligomerization state equivalent to those of the wild type, produced high-titer antisera, and avoided disruption of B-cell epitopes of ADI. In addition, antisera raised against the D166A and D277A mutant proteins bound to the GAS cell surface. The inactivated D166A and D277A mutant ADIs are ideal for inclusion in a GAS vaccine preparation. There is no human ortholog of ADI, and we confirm that despite limited structural similarity in the active-site region to human peptidyl ADI 4 (PAD4), ADI does not functionally mimic PAD4 and antiserum raised against GAS ADI does not recognize human PAD4. We present an example of structural biology informing human vaccine design. We previously showed that the administration of the enzyme arginine deiminase (ADI) to mice protected the mice against infection with multiple GAS serotypes. In this study, we determined the structure of GAS ADI and used this information to improve the vaccine safety of GAS ADI. Catalytically inactive mutant forms of ADI retained structure, recognition by antisera, and immunogenic epitopes, rendering them ideal for inclusion in GAS vaccine preparations. This example of structural biology informing vaccine design may underpin the formulation of a safe and efficacious GAS vaccine.
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