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Zhou X, Song H, Pan F, Yuan C, Jia L, Wu B, Fan H, Ma Z. The dual M protein systems have diverse biological characteristics, but both contribute to M18-type Group A Streptococcus pathogenicity. Microbes Infect 2023:105209. [PMID: 37597608 DOI: 10.1016/j.micinf.2023.105209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 08/05/2023] [Accepted: 08/07/2023] [Indexed: 08/21/2023]
Abstract
M protein is a key surface virulence factor in Group A Streptococcus (GAS), Group C Streptococcus (GCS), and other streptococcal species. GAS encodes M protein using the emm gene, while GCS employs the szm (or sem) gene. In M18-type GAS, dual M protein systems exist, comprising both GAS and GCS M proteins (encoded separately by emm18 and spa18). The spa18 gene in M18-type GAS shares a conserved region highly similar to GCS's szm gene. Our study reveals that spa18 exhibits higher transcription levels than emm18 in M18-type GAS strains. The dual M protein systems defective mutant (Δemm18Δspa18) displays a smooth surface, whereas wild-type and single M protein gene mutants remain rough. M18 and SPA18 proteins possess distinct characteristics, showing varied binding properties and cytotoxicity effects on macrophages (THP-1) and keratinocytes (HaCaT). Both emm18 and spa18 genes contribute to the skin pathogenicity of M18-type GAS. Transcriptome analysis suggests the potential involvement of the mga gene in spa18 transcription regulation, while SpyM18_2047 appears to be specific to spa18 regulation. In summary, this research offers a crucial understanding of the biological characteristics of dual M protein systems in M18-type GAS, highlighting their contributions to virulence and transcriptional regulation.
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Affiliation(s)
- Xiaorui Zhou
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Ministry of Agriculture Key Laboratory of Animal Bacteriology, Nanjing 210095, China
| | - Haoshuai Song
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Ministry of Agriculture Key Laboratory of Animal Bacteriology, Nanjing 210095, China
| | - Fei Pan
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Ministry of Agriculture Key Laboratory of Animal Bacteriology, Nanjing 210095, China
| | - Chen Yuan
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Ministry of Agriculture Key Laboratory of Animal Bacteriology, Nanjing 210095, China
| | - Lu Jia
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Ministry of Agriculture Key Laboratory of Animal Bacteriology, Nanjing 210095, China
| | - Bing Wu
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Ministry of Agriculture Key Laboratory of Animal Bacteriology, Nanjing 210095, China
| | - Hongjie Fan
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Ministry of Agriculture Key Laboratory of Animal Bacteriology, Nanjing 210095, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China
| | - Zhe Ma
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Ministry of Agriculture Key Laboratory of Animal Bacteriology, Nanjing 210095, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China.
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2
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D'Gama JD, Ma Z, Zhang H, Liu X, Fan H, Morris ERA, Cohen ND, Cywes-Bentley C, Pier GB, Waldor MK. A Conserved Streptococcal Virulence Regulator Controls the Expression of a Distinct Class of M-Like Proteins. mBio 2019; 10:e02500-19. [PMID: 31641092 PMCID: PMC6805998 DOI: 10.1128/mbio.02500-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 09/23/2019] [Indexed: 12/16/2022] Open
Abstract
Streptococcus equi subspecies zooepidemicus (SEZ) are group C streptococci that are important pathogens of economically valuable animals such as horses and pigs. Here, we found that many SEZ isolates bind to a monoclonal antibody that recognizes poly-N-acetylglucosamine (PNAG), a polymer that is found as a surface capsule-like structure on diverse microbes. A fluorescence-activated cell sorting-based transposon insertion sequencing (Tn-seq) screen, coupled with whole-genome sequencing, was used to search for genes for PNAG biosynthesis. Surprisingly, mutations in a gene encoding an M-like protein, szM, and the adjacent transcription factor, designated sezV, rendered strains PNAG negative. SezV was required for szM expression and transcriptome analysis showed that SezV has a small regulon. SEZ strains with inactivating mutations in either sezV or szM were highly attenuated in a mouse model of infection. Comparative genomic analyses revealed that linked sezV and szM homologues are present in all SEZ, S. equi subspecies equi (SEE), and M18 group A streptococcal (GAS) genomes in the database, but not in other streptococci. The antibody to PNAG bound to a wide range of SEZ, SEE, and M18 GAS strains. Immunochemical studies suggest that the SzM protein may be decorated with a PNAG-like oligosaccharide although an intact oligosaccharide substituent could not be isolated. Collectively, our findings suggest that the szM and sezV loci define a subtype of virulent streptococci and that an antibody to PNAG may have therapeutic applications in animal and human diseases caused by streptococci bearing SzM-like proteins.IMPORTANCE M proteins are surface-anchored virulence factors in group A streptococci, human pathogens. Here, we identified an M-like protein, SzM, and its positive regulator, SezV, in Streptococcus equi subspecies zooepidemicus (SEZ), an important group of pathogens for domesticated animals, including horses and pigs. SzM and SezV homologues were found in the genomes of all SEZ and S. equi subspecies equi and M18 group A streptococcal strains analyzed but not in other streptococci. Mutant SEZ strains lacking either sezV or szM were highly attenuated in a mouse model of infection. Collectively, our findings suggest that SezV-related regulators and the linked SzM family of M-like proteins define a new subset of virulent streptococci.
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Affiliation(s)
- Jonathan D D'Gama
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
- Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Zhe Ma
- Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts, USA
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, China
- Ministry of Agriculture Key Laboratory of Animal Bacteriology, Nanjing, Jiangsu, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, China
| | - Hailong Zhang
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
- Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Xu Liu
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
- Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Hongjie Fan
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, China
- Ministry of Agriculture Key Laboratory of Animal Bacteriology, Nanjing, Jiangsu, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, China
| | - Ellen Ruth A Morris
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, College Station, Texas, USA
| | - Noah D Cohen
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, College Station, Texas, USA
| | - Colette Cywes-Bentley
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
- Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Gerald B Pier
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
- Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Matthew K Waldor
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
- Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts, USA
- Howard Hughes Medical Institute, Boston, Massachusetts, USA
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3
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Bao YJ, Li Y, Liang Z, Agrahari G, Lee SW, Ploplis VA, Castellino FJ. Comparative pathogenomic characterization of a non-invasive serotype M71 strain Streptococcus pyogenes NS53 reveals incongruent phenotypic implications from distinct genotypic markers. Pathog Dis 2017; 75:3829887. [PMID: 28520869 DOI: 10.1093/femspd/ftx056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 05/16/2017] [Indexed: 11/15/2022] Open
Abstract
The strains serotyped as M71 from group A Streptococcus are common causes of pharyngeal and skin diseases worldwide. Here we characterize the genome of a unique non-invasive M71 human isolate, NS53. The genome does not contain structural rearrangements or large-scale gene gains/losses, but encodes a full set of non-truncated known virulence factors, thus providing an ideal reference for comparative studies. However, the NS53 genome showed incongruent phenotypic implications from distinct genotypic markers. NS53 is characterized as an emm pattern D and FCT (fibronectin-collagen-T antigen) type-3 strain, typical of skin tropic strains, but is phylogenetically close to emm pattern E strains with preference for both skin and pharyngeal infections. We propose that this incongruence could result from recombination within the emm gene locus, or, alternatively, selection has been against those genetic alterations. Combined with the inability to select for CovS switching, a process is indicated whereby NS53 has been pre-adapted to specific host niches selecting against variations in CovS and many other genes. This may allow the strain to attain successful colonization and long-term survival. A balance between genetic variations and fitness may exist for this bacterium to form a stabilized genome optimized for survival in specific host environments.
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Affiliation(s)
- Yun-Juan Bao
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Yang Li
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, USA.,Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Zhong Liang
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, USA.,Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Garima Agrahari
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, USA.,Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Shaun W Lee
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, USA.,Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Victoria A Ploplis
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, USA.,Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Francis J Castellino
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, USA.,Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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4
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Gandhi GD, Krishnamoorthy N, Motal UMA, Yacoub M. Towards developing a vaccine for rheumatic heart disease. Glob Cardiol Sci Pract 2017; 2017:e201704. [PMID: 28971103 PMCID: PMC5621712 DOI: 10.21542/gcsp.2017.4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Rheumatic heart disease (RHD) is the most serious manifestations of rheumatic fever, which is caused by group A Streptococcus (GAS or Streptococcus pyogenes) infection. RHD is an auto immune sequelae of GAS pharyngitis, rather than the direct bacterial infection of the heart, which leads to chronic heart valve damage. Although antibiotics like penicillin are effective against GAS infection, improper medical care such as poor patient compliance, overcrowding, poverty, and repeated exposure to GAS, leads to acute rheumatic fever and RHD. Thus, efforts have been put forth towards developing a vaccine. However, a potential global vaccine is yet to be identified due to the widespread diversity of S. pyogenes strains and cross reactivity of streptococcal proteins with host tissues. In this review, we discuss the available vaccine targets of S. pyogenes and the significance of in silico approaches in designing a vaccine for RHD.
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Affiliation(s)
- Geethanjali Devadoss Gandhi
- Division of Cardiovascular Research, Sidra Medical and Research Center, Qatar Foundation, Doha, Qatar.,Division of Experimental Genetics, Sidra Medical and Research Center, Doha, Qatar
| | - Navaneethakrishnan Krishnamoorthy
- Division of Cardiovascular Research, Sidra Medical and Research Center, Qatar Foundation, Doha, Qatar.,Division of Experimental Genetics, Sidra Medical and Research Center, Doha, Qatar.,Heart Science Centre, National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Ussama M Abdel Motal
- Division of Cardiovascular Research, Sidra Medical and Research Center, Qatar Foundation, Doha, Qatar
| | - Magdi Yacoub
- Division of Cardiovascular Research, Sidra Medical and Research Center, Qatar Foundation, Doha, Qatar.,Heart Science Centre, National Heart and Lung Institute, Imperial College London, London, United Kingdom
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5
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Group A streptococcus expresses a trio of surface proteins containing protective epitopes. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2014; 21:1421-5. [PMID: 25080552 DOI: 10.1128/cvi.00448-14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Group A streptococci (GAS) (Streptococcus pyogenes) are common causes of infections in humans for which there is no licensed vaccine. Decades of work has focused on the role of the surface M protein in eliciting type-specific protective immunity. Recent studies have identified additional surface proteins of GAS that contain opsonic epitopes. In the present study, we describe a serotype M65 GAS originally isolated during an epidemiologic study in Bamako, Mali, which simultaneously expressed M, M-related protein (Mrp), and streptococcal protective antigen (Spa) on the bacterial surface. The emm, mrp, and spa genes were sequenced from PCR amplicons derived from the M65 chromosome. Rabbit antisera raised against synthetic peptides copying the N-terminal regions of M, Mrp, and Spa were highly specific for each peptide, reacted with the surface of M65 GAS, and promoted bactericidal activity against the organism. A mixture of antisera against all three peptides was most effective in the bactericidal assays. Immunofluorescence microscopy revealed that the M, Mrp, and Spa antisera bound to the bacterial surface in the presence of human plasma proteins and resulted in the deposition of complement. Five additional spa genes were identified in the Mrp-positive GAS serotypes, and their sequences were determined. Our results indicate that there are multiple antigens on the surface of GAS that evoke antibodies that promote bacterial killing. A more complete understanding of the relative contributions of M, Mrp, and Spa in eliciting protective immunity may aid in the development of GAS vaccines with enhanced coverage and efficacy.
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Henningham A, Gillen CM, Walker MJ. Group a streptococcal vaccine candidates: potential for the development of a human vaccine. Curr Top Microbiol Immunol 2012; 368:207-42. [PMID: 23250780 DOI: 10.1007/82_2012_284] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Currently there is no commercial Group A Streptococcus (GAS; S. pyogenes) vaccine available. The development of safe GAS vaccines is challenging, researchers are confronted with obstacles such as the occurrence of many unique serotypes (there are greater than 150 M types), antigenic variation within the same serotype, large variations in the geographical distribution of serotypes, and the production of antibodies cross-reactive with human tissue which can lead to host auto-immune disease. Cell wall anchored, cell membrane associated, secreted and anchorless proteins have all been targeted as GAS vaccine candidates. As GAS is an exclusively human pathogen, the quest for an efficacious vaccine is further complicated by the lack of an animal model which mimics human disease and can be consistently and reproducibly colonized by multiple GAS strains.
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Affiliation(s)
- Anna Henningham
- School of Chemistry and Molecular Biosciences and Australian Infectious Disease Research Centre, University of Queensland, St Lucia, QLD 4072, Australia
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7
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Abstract
Group A Streptococcus (GAS) is a human-specific pathogen that is highly prevalent throughout the world. The vast majority of GAS infections lead to a mild disease involving the epithelial surfaces of either the throat or skin. The concept of distinct sets of 'throat' and 'skin' strains of GAS has long been conceived. From an ecological standpoint, the epithelium of the throat and skin are important because it is where the organism is most successful in reproducing and transmitting to new hosts. This article examines key features of the epidemiology, population biology and molecular pathogenesis that underlie the tissue site preferences for infection exhibited by GAS, with an emphasis on work from our laboratory on skin tropisms. Recombinational replacement with orthologous gene forms, following interspecies transfer, appears to be an important genetic step leading up to the exploitation of new niches by GAS.
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Affiliation(s)
- Debra E Bessen
- Department of Microbiology & Immunology, New York Medical College, Valhalla, NY 10573, USA, Tel.: +1 914 594 4193, Fax: +1 914 594 4176
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8
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Ahmed EA, Penfound TA, Brewer SC, Tennant PA, Chiang EY, Dale JB. Streptococcal protective antigens (Spa): a new family of type-specific proteins of group A streptococci. Eur J Clin Microbiol Infect Dis 2009; 29:51-7. [PMID: 19865839 DOI: 10.1007/s10096-009-0819-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Accepted: 09/15/2009] [Indexed: 11/26/2022]
Abstract
Previous studies in our laboratory described a new group A streptococcal protective antigen (Spa) in type 18 streptococci that was distinct from the type 18 M protein. This study was undertaken to identify additional serotypes of group A streptococci that express Spa proteins. PCR techniques were used to identify and clone a new spa gene from type 36 streptococci. The 5' sequence of spa36 was highly variable compared to spa18, while the 3' sequence was conserved. Antisera against Spa36 opsonized type 36 streptococci but not type 18 streptococci, indicating that the opsonic Spa epitopes were type-specific. Antisera against the conserved carboxy-terminal half of Spa18 were used to identify Spa or Spa-like proteins expressed on the surface of 25 of 70 different serotypes of GAS. Spa proteins may represent a new family of type-specific surface antigens that function in concert with M proteins to elicit protective immune responses.
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Affiliation(s)
- E A Ahmed
- Department of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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9
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Meehan M, Lewis MJ, Byrne C, O'Hare D, Woof JM, Owen P. Localization of the equine IgG-binding domain in the fibrinogen-binding protein (FgBP) of Streptococcus equi subsp. equi. MICROBIOLOGY-SGM 2009; 155:2583-2592. [PMID: 19423628 DOI: 10.1099/mic.0.028845-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Fibrinogen-binding protein (FgBP, also termed SeM) is a cell-wall-associated anti-phagocytic M-like protein of the equine pathogen Streptococcus equi subsp. equi, and binds fibrinogen (Fg) and IgG. FgBP binds Fg avidly through residues located at the extreme N terminus of the molecule, whereas the IgG-binding site is more centrally located between the A and B repeats. FgBP binds equine IgG4 and IgG7 subclasses through interaction with the CH2-CH3 interdomain region of IgG-Fc, and possesses overlapping Fc-binding sites with protein A and protein G. In this study, FgBP truncates containing defined internal deletions were used to identify a stretch of 14 aa (residues 335-348) critical for IgG binding. Protein chimeras consisting of the non-IgG-binding alpha-helical coiled-coil M5 protein fused to FgBP sequences were used to identify a minimal equine IgG-binding domain consisting of residues 329-360. Competition ELISA tests suggested that IgG does not compromise Fg binding and vice versa.
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Affiliation(s)
- Mary Meehan
- Department of Microbiology, Moyne Institute of Preventative Medicine, Trinity College, Dublin 2, Ireland
| | - Melanie J Lewis
- Division of Medical Sciences, University of Dundee Medical School, Ninewells Hospital, Dundee DD1 9SY, UK
| | - Caroline Byrne
- Department of Microbiology, Moyne Institute of Preventative Medicine, Trinity College, Dublin 2, Ireland
| | - David O'Hare
- Department of Microbiology, Moyne Institute of Preventative Medicine, Trinity College, Dublin 2, Ireland
| | - Jenny M Woof
- Division of Medical Sciences, University of Dundee Medical School, Ninewells Hospital, Dundee DD1 9SY, UK
| | - Peter Owen
- Department of Microbiology, Moyne Institute of Preventative Medicine, Trinity College, Dublin 2, Ireland
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10
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Oliver MA, Rojo JM, Rodríguez de Córdoba S, Alberti S. Binding of complement regulatory proteins to group A Streptococcus. Vaccine 2009; 26 Suppl 8:I75-8. [PMID: 19388169 DOI: 10.1016/j.vaccine.2008.11.054] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Streptococcus pyogenes or Group A Streptococcus (GAS) is the etiologic agent of important human infections such as acute pharyngitis, impetigo, rheumatic fever and the streptococcal toxic shock syndrome. Binding of the complement regulatory proteins factor H, factor H-like protein 1 (FHL-1), C4b-binding protein (C4BP), or CD46 is a crucial step in the pathogenesis of these infections. M protein is the GAS protein that generally mediates these interactions. However, a detailed analysis of the reports that have investigated the binding of complement regulatory components to GAS indicates that this microorganism has evolved alternative mechanisms for the recruitment of complement regulatory proteins to the bacterial surface. This article summarizes these data to provide a starting point for future research aimed at the characterization of additional mechanisms developed by GAS to evade the immune system.
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Affiliation(s)
- Maria A Oliver
- Institut Universitari d'Investigacions en Ciències de la Salut, Universitat de les Illes Balears, Crtra. Valldemosa, km 7.5, 07122 Palma de Mallorca, Spain
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11
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Inactivation of DltA modulates virulence factor expression in Streptococcus pyogenes. PLoS One 2009; 4:e5366. [PMID: 19401780 PMCID: PMC2671602 DOI: 10.1371/journal.pone.0005366] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Accepted: 04/02/2009] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND D-alanylated lipoteichoic acid is a virtually ubiquitous component of gram-positive cell walls. Mutations in the dltABCD operon of numerous species exhibit pleiotropic effects, including reduced virulence, which has been attributed to increased binding of cationic antimicrobial peptides to the more negatively charged cell surface. In this study, we have further investigated the effects that mutating dltA has on virulence factor expression in Streptococcus pyogenes. METHODOLOGY/PRINCIPAL FINDINGS Isogenic Delta dltA mutants had previously been created in two distinct M1T1 isolates of S. pyogenes. Immunoblots, flow cytometry, and immunofluorescence were used to quantitate M protein levels in these strains, as well as to assess their ability to bind complement. Bacteria were tested for their ability to interact with human PMN and to grow in whole human blood. Message levels for emm, sic, and various regulatory elements were assessed by quantitative RT-PCR. Cell walls of Delta dltA mutants contained much less M protein than cell walls of parent strains and this correlated with reduced levels of emm transcripts, increased deposition of complement, increased association of bacteria with polymorphonuclear leukocytes, and reduced bacterial growth in whole human blood. Transcription of at least one other gene of the mga regulon, sic, which encodes a protein that inactivates antimicrobial peptides, was also dramatically reduced in Delta dltA mutants. Concomitantly, ccpA and rofA were unaffected, while rgg and arcA were up-regulated. CONCLUSIONS/SIGNIFICANCE This study has identified a novel mechanism for the reduced virulence of dltA mutants of Streptococcus pyogenes in which gene regulatory networks somehow sense and respond to the loss of DltA and lack of D-alanine esterification of lipoteichoic acid. The mechanism remains to be determined, but the data indicate that the status of D-alanine-lipoteichoic acid can significantly influence the expression of at least some streptococcal virulence factors and provide further impetus to targeting the dlt operon of gram-positive pathogens in the search for novel antimicrobial compounds.
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12
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Relationship between expression of the family of M proteins and lipoteichoic acid to hydrophobicity and biofilm formation in Streptococcus pyogenes. PLoS One 2009; 4:e4166. [PMID: 19132104 PMCID: PMC2613554 DOI: 10.1371/journal.pone.0004166] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Accepted: 12/06/2008] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Hydrophobicity is an important attribute of bacteria that contributes to adhesion and biofilm formation. Hydrophobicity of Streptococcus pyogenes is primarily due to lipoteichoic acid (LTA) on the streptococcal surface but the mechanism(s) whereby LTA is retained on the surface is poorly understood. In this study, we sought to determine whether members of the M protein family consisting of Emm (M protein), Mrp (M-related protein), Enn (an M-like protein), and the streptococcal protective antigen (Spa) are involved in anchoring LTA in a manner that contributes to hydrophobicity of the streptococci and its ability to form biofilms. METHODOLOGY/PRINCIPAL FINDINGS Isogenic mutants defective in expression of emm, mrp, enn, and/or spa genes of eight different serotypes and their parental strains were tested for differences in LTA bound to surface proteins, LTA released into the culture media, and membrane-bound LTA. The effect of these mutations on the ability of streptococci to form a hydrophobic surface and to generate biofilms was also investigated. A recombinant strain overexpressing Emm1 was also engineered and similarly tested. The serotypes tested ranged from those that express only a single M protein gene to those that express two or three members of the M protein family. Overexpression of Emm1 led to enhanced hydrophobicity and biofilm formation. Inactivation of emm in those serotypes expressing only a single emm gene reduced biofilm formation, and protein-bound LTA on the surface, but did not alter the levels of membrane-bound LTA. The results were more varied in those serotypes that express two to three members of the M protein family. CONCLUSIONS/SIGNIFICANCE Our findings suggest that the formation of complexes with members of the M protein family is a common mechanism for anchoring LTA on the surface in a manner that contributes to hydrophobicity and to biofilm formation in S. pyogenes, but these activities in some serotypes are dependent on a trypsin-sensitive protein(s) that remains to be identified. The need for interactions between LTA and M proteins may impose functional constraints that limit variations in the sequence of the M proteins, major virulence factors of S. pyogenes.
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13
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Kotloff KL. Streptococcus group A vaccines. Vaccines (Basel) 2008. [DOI: 10.1016/b978-1-4160-3611-1.50062-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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14
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McMillan DJ, Sriprakash KS, Chhatwal GS. Genetic variation in group A streptococci. Int J Med Microbiol 2007; 297:525-32. [PMID: 17459766 DOI: 10.1016/j.ijmm.2007.02.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 02/19/2007] [Accepted: 02/19/2007] [Indexed: 10/23/2022] Open
Abstract
Group A streptococcus (GAS) is responsible for a range of human diseases that vary in their clinical manifestations and severity. While numerous virulence factors have been described, the way these factors interact to promote different streptococcal diseases is less clear. In order to identify multifactorial relationships between GAS and the human host, novel high-throughput techniques such as microarrays are necessary. We have performed comparative studies using custom-designed virulence arrays to enhance our understanding of the high degree of genotypic variation that occurs in streptococci. This study has pointed to mobile genetic elements as the major agents that promote variation. Our results show that multiple combinations of genes might bring about similar clinical pictures. This adds further complexity to the intricate relationship between pathogen and host.
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Affiliation(s)
- David J McMillan
- Department of Microbial Pathogenesis, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, D-38124 Braunschweig, Germany
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McMillan DJ, Beiko RG, Geffers R, Buer J, Schouls LM, Vlaminckx BJM, Wannet WJB, Sriprakash KS, Chhatwal GS. Genes for the majority of group a streptococcal virulence factors and extracellular surface proteins do not confer an increased propensity to cause invasive disease. Clin Infect Dis 2006; 43:884-91. [PMID: 16941370 DOI: 10.1086/507537] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2006] [Accepted: 06/15/2006] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND The factors behind the reemergence of severe, invasive group A streptococcal (GAS) diseases are unclear, but it could be caused by altered genetic endowment in these organisms. However, data from previous studies assessing the association between single genetic factors and invasive disease are often conflicting, suggesting that other, as-yet unidentified factors are necessary for the development of this class of disease. METHODS In this study, we used a targeted GAS virulence microarray containing 226 GAS genes to determine the virulence gene repertoires of 68 GAS isolates (42 associated with invasive disease and 28 associated with noninvasive disease) collected in a defined geographic location during a contiguous time period. We then employed 3 advanced machine learning methods (genetic algorithm neural network, support vector machines, and classification trees) to identify genes with an increased association with invasive disease. RESULTS Virulence gene profiles of individual GAS isolates varied extensively among these geographically and temporally related strains. Using genetic algorithm neural network analysis, we identified 3 genes with a marginal overrepresentation in invasive disease isolates. Significantly, 2 of these genes, ssa and mf4, encoded superantigens but were only present in a restricted set of GAS M-types. The third gene, spa, was found in variable distributions in all M-types in the study. CONCLUSIONS Our comprehensive analysis of GAS virulence profiles provides strong evidence for the incongruent relationships among any of the 226 genes represented on the array and the overall propensity of GAS to cause invasive disease, underscoring the pathogenic complexity of these diseases, as well as the importance of multiple bacteria and/or host factors.
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Affiliation(s)
- David J McMillan
- German Research Centre for Biotechnology, Braunschweig, Germany.
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Courtney HS, Hasty DL, Dale JB. Anti-phagocytic mechanisms of Streptococcus pyogenes: binding of fibrinogen to M-related protein. Mol Microbiol 2006; 59:936-47. [PMID: 16420362 DOI: 10.1111/j.1365-2958.2005.04977.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A key attribute of invasive Streptococcus pyogenes is their ability to resist phagocytosis and multiply in human blood. M-related protein (Mrp) is a major anti-phagocytic factor but the mechanism whereby it helps streptococci to evade phagocytosis has not been demonstrated. We investigated phagocytosis resistance in a strain of serotype M4 by inactivating the mrp gene and also the emm, enn, sof and sfbX genes and by analysing the effect on streptococcal growth in blood and on complement deposition on the bacterial surface. Inactivation of enn4 and sfbX4 had little impact on growth in blood, but ablation of mrp4, emm4 or sof4 reduced streptococcal growth in human blood, confirming that Mrp and Emm are required for optimal resistance to phagocytosis and providing the first indication that Sof may be an anti-phagocytic factor. Moreover, antisera against Mrp4, Emm4 and Sof4 promoted the killing of S. pyogenes, but anti-SfbX serum had no effect. Growth of S. pyogenes in blood was dependent on the presence of fibrinogen and in the absence of fibrinogen there was a twofold increase in complement deposition. Inactivation of mrp4 resulted in a loss of fibrinogen-binding and caused a twofold increase in the binding of C3b that was inhibited by Mg-EGTA. Mrp contained two fibrinogen-binding sites, one of which is within a highly conserved region. These findings indicate that Mrp-fibrinogen interactions prevent surface deposition of complement via the classical pathway, thereby contributing to the ability of these streptococci to resist phagocytosis. This may be a common mechanism for evasion of phagocytosis because Mrp is expressed by approximately half of the clinical isolates of S. pyogenes.
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Affiliation(s)
- Harry S Courtney
- Veterans Affairs Medical Center, University of Tennessee Health Science Center, Memphis, TN 38104, USA.
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Courtney HS, Hasty DL, Dale JB. Serum opacity factor (SOF) of Streptococcus pyogenes evokes antibodies that opsonize homologous and heterologous SOF-positive serotypes of group A streptococci. Infect Immun 2003; 71:5097-103. [PMID: 12933852 PMCID: PMC187301 DOI: 10.1128/iai.71.9.5097-5103.2003] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Serum opacity factor (SOF) is a protein expressed by Streptococcus pyogenes that opacifies mammalian serum. SOF is also a virulence factor of S. pyogenes, but it has not been previously shown to elicit a protective immune response. Herein, we report that SOF evokes bactericidal antibodies against S. pyogenes in humans, rabbits, and mice. Rabbit antiserum against purified recombinant SOF2 opsonized SOF-positive M type 2, 4, and 28 S. pyogenes in human blood but had no effect on SOF-negative M type 5 S. pyogenes. Furthermore, affinity-purified human antibodies against SOF2 also opsonized SOF-positive streptococci. A combination of antisera against M2 and SOF2 proteins was dramatically more effective in killing streptococci than either antiserum alone, indicating that antibodies against SOF2 enhance the opsonic efficiency of M protein antibodies. Mice tolerated an intravenous injection of 100 microg of SOF without overt signs of toxicity, and immunization with SOF protected mice against challenge infections with M type 2 S. pyogenes. These data indicate that SOF evokes opsonic antibodies that may protect against infections by SOF-positive serotypes of group A streptococci and suggest that different serotypes of SOF have common epitopes that may be useful vaccine candidates to protect against group A streptococcal infections.
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Affiliation(s)
- Harry S Courtney
- Veterans Affairs Medical Center and Department of Medicine, University of Tennessee, Memphis, Tennessee 38104, USA.
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Dale JB, Chiang EY, Hasty DL, Courtney HS. Antibodies against a synthetic peptide of SagA neutralize the cytolytic activity of streptolysin S from group A streptococci. Infect Immun 2002; 70:2166-70. [PMID: 11895983 PMCID: PMC127879 DOI: 10.1128/iai.70.4.2166-2170.2002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Virtually all group A streptococci (GAS) produce streptolysin S (SLS), a cytolytic toxin that is responsible for the beta-hemolysis surrounding colonies of the organisms grown on blood agar. SLS is an important virulence determinant of GAS, and recent studies have identified a nine-gene locus that is responsible for synthesis and transport of the toxin. SLS is not immunogenic; thus, no neutralizing antibodies are evoked during the course of natural infection. In the present study, we show that a synthetic peptide containing amino acid residues 10 to 30 of the putative SLS (SagA) propeptide [SLS(10-30)] coupled to keyhole limpet hemocyanin evoked antibodies in rabbits that completely neutralized the hemolytic activity of the toxin in vitro. Inhibition of hemolysis was reversed by preincubation of the immune serum with soluble, unconjugated peptide, indicating the specificity of the antibodies. In addition, antibodies that were affinity purified over an SLS(10-30) peptide column completely inhibited SLS-mediated hemolysis. The SLS(10-30) antisera did not opsonize group A streptococci; however, when combined with type-specific M protein antisera, the SLS antibodies significantly enhanced phagocytosis mediated by M protein antibodies. Thus, we have shown for the first time that it is possible to raise neutralizing antibodies against one of the most potent bacterial cytolytic toxins known. Our data also provide convincing evidence that the sagA gene actually encodes the SLS peptide of GAS. The synthetic peptide may prove to be an important component of vaccines designed to prevent GAS infections.
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Affiliation(s)
- James B Dale
- Department of Veterans Affairs Medical Center and Department of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee 38104, USA.
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Barnett TC, Scott JR. Differential recognition of surface proteins in Streptococcus pyogenes by two sortase gene homologs. J Bacteriol 2002; 184:2181-91. [PMID: 11914350 PMCID: PMC134975 DOI: 10.1128/jb.184.8.2181-2191.2002] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The interaction of Streptococcus pyogenes (group A streptococcus [GAS]) with its human host requires several surface proteins. In this study, we isolated mutations in a gene required for the surface localization of protein F by transposon mutagenesis of the M6 strain JRS4. This gene (srtA) encodes a protein homologous to Staphylococcus aureus sortase, which covalently links proteins containing an LPXTG motif to the cell wall. The GAS srtA mutant was defective in anchoring the LPXTG-containing proteins M6, protein F, ScpA, and GRAB to the cell surface. This phenotype was complemented when a wild-type srtA gene was provided in trans. The surface localization of T6, however, was unaffected by the srtA mutation. The M1 genome sequence contains a second open reading frame with a motif characteristic of sortase proteins. Inactivation of this gene (designated srtB) in strain JRS4 affected the surface localization of T6 but not M6, protein F, ScpA, or GRAB. This phenotype was complemented by srtB in trans. An srtA probe hybridized with DNA from all GAS strains tested (M types 1, 3, 4, 5, 6, 18, 22, and 50 and nontypeable strain 64/14) and from streptococcal groups C and G, while srtB hybridized with DNA from only a few GAS strains. We conclude that srtA and srtB encode sortase enzymes required for anchoring different subsets of proteins to the cell wall. It seems likely that the multiple sortase homologs in the genomes of other gram-positive bacteria have a similar substrate-specific role.
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Affiliation(s)
- Timothy C Barnett
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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Hu MC, Walls MA, Stroop SD, Reddish MA, Beall B, Dale JB. Immunogenicity of a 26-valent group A streptococcal vaccine. Infect Immun 2002; 70:2171-7. [PMID: 11895984 PMCID: PMC127884 DOI: 10.1128/iai.70.4.2171-2177.2002] [Citation(s) in RCA: 185] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2001] [Revised: 12/19/2001] [Accepted: 01/18/2002] [Indexed: 11/20/2022] Open
Abstract
A multivalent vaccine containing amino-terminal M protein fragments from 26 different serotypes of group A streptococci was constructed by recombinant techniques. The vaccine consisted of four different recombinant proteins that were formulated with alum to contain 400 microg of protein per dose. Rabbits were immunized via the intramuscular route at 0, 4, and 16 weeks. Immune sera were assayed for the presence of type-specific antibodies against the individual recombinant M peptides by enzyme-linked immunosorbent assay and for opsonic antibodies by in vitro opsonization tests and indirect bactericidal tests. The 26-valent vaccine was highly immunogenic and elicited fourfold or greater increases in antibody levels against 25 of the 26 serotypes represented in the vaccine. The immune sera were broadly opsonic and were bactericidal against the majority of the 26 different serotypes. Importantly, none of the immune sera cross-reacted with human tissues. Our results indicate that type-specific, protective M protein epitopes can be incorporated into complex, multivalent vaccines designed to elicit broadly protective opsonic antibodies in the absence of tissue-cross-reactive antibodies.
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Affiliation(s)
- Mary C Hu
- ID Biomedical Corporation, Bothell, Washington, USA
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