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Mitchell C, Steward KF, Charbonneau ARL, Walsh S, Wilson H, Timoney JF, Wernery U, Joseph M, Craig D, van Maanen K, Hoogkamer-van Gennep A, Leon A, Witkowski L, Rzewuska M, Stefańska I, Żychska M, van Loon G, Cursons R, Patty O, Acke E, Gilkerson JR, El-Hage C, Allen J, Bannai H, Kinoshita Y, Niwa H, Becú T, Pringle J, Guss B, Böse R, Abbott Y, Katz L, Leggett B, Buckley TC, Blum SE, Cruz López F, Fernández Ros A, Marotti Campi MC, Preziuso S, Robinson C, Newton JR, Schofield E, Brooke B, Boursnell M, de Brauwere N, Kirton R, Barton CK, Abudahab K, Taylor B, Yeats CA, Goater R, Aanensen DM, Harris SR, Parkhill J, Holden MTG, Waller AS. Globetrotting strangles: the unbridled national and international transmission of Streptococcus equi between horses. Microb Genom 2021; 7:mgen000528. [PMID: 33684029 PMCID: PMC8190609 DOI: 10.1099/mgen.0.000528] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 01/13/2021] [Indexed: 02/02/2023] Open
Abstract
The equine disease strangles, which is characterized by the formation of abscesses in the lymph nodes of the head and neck, is one of the most frequently diagnosed infectious diseases of horses around the world. The causal agent, Streptococcus equi subspecies equi, establishes a persistent infection in approximately 10 % of animals that recover from the acute disease. Such 'carrier' animals appear healthy and are rarely identified during routine veterinary examinations pre-purchase or transit, but can transmit S. equi to naïve animals initiating new episodes of disease. Here, we report the analysis and visualization of phylogenomic and epidemiological data for 670 isolates of S. equi recovered from 19 different countries using a new core-genome multilocus sequence typing (cgMLST) web bioresource. Genetic relationships among all 670 S. equi isolates were determined at high resolution, revealing national and international transmission events that drive this endemic disease in horse populations throughout the world. Our data argue for the recognition of the international importance of strangles by the Office International des Épizooties to highlight the health, welfare and economic cost of this disease. The Pathogenwatch cgMLST web bioresource described herein is available for tailored genomic analysis of populations of S. equi and its close relative S. equi subspecies zooepidemicus that are recovered from horses and other animals, including humans, throughout the world. This article contains data hosted by Microreact.
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Affiliation(s)
| | - Karen F. Steward
- Animal Health Trust, Newmarket, UK
- Present address: Technology Networks, Sudbury, UK
| | | | - Saoirse Walsh
- Animal Health Trust, Newmarket, UK
- Present address: University of Berlin, Berlin, Germany
| | - Hayley Wilson
- Animal Health Trust, Newmarket, UK
- Present address: University of Cambridge, Cambridge, UK
| | | | - Ulli Wernery
- Central Veterinary Research Laboratory, Dubai, UAE
| | | | | | | | | | | | - Lucjan Witkowski
- Institute of Veterinary Medicine, Warsaw University of Life Sciences – SGGW, Warsaw, Poland
| | - Magdalena Rzewuska
- Institute of Veterinary Medicine, Warsaw University of Life Sciences – SGGW, Warsaw, Poland
| | - Ilona Stefańska
- Institute of Veterinary Medicine, Warsaw University of Life Sciences – SGGW, Warsaw, Poland
| | - Monika Żychska
- Institute of Veterinary Medicine, Warsaw University of Life Sciences – SGGW, Warsaw, Poland
| | | | - Ray Cursons
- University of Waikato, Hamilton, New Zealand
| | | | - Els Acke
- Massey University, Palmerston North, New Zealand
| | | | | | | | | | | | | | | | - John Pringle
- Department of Biomedical Science and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Bengt Guss
- Department of Biomedical Science and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | | | | | - Lisa Katz
- University College Dublin, Dublin, Ireland
| | | | | | | | | | | | | | | | | | | | - Ellen Schofield
- Animal Health Trust, Newmarket, UK
- Present address: University of Cambridge, Cambridge, UK
| | | | | | | | - Roxane Kirton
- Redwings Horse Sanctuary, Norwich, UK
- Present address: Royal Society for the Prevention of Cruelty to Animals, Horsham, UK
| | | | - Khalil Abudahab
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Centre for Genomic Pathogen Surveillance, Wellcome Trust Sanger Institute, Cambridge, UK
| | - Ben Taylor
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Centre for Genomic Pathogen Surveillance, Wellcome Trust Sanger Institute, Cambridge, UK
| | - Corin A. Yeats
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Centre for Genomic Pathogen Surveillance, Wellcome Trust Sanger Institute, Cambridge, UK
| | - Richard Goater
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Centre for Genomic Pathogen Surveillance, Wellcome Trust Sanger Institute, Cambridge, UK
| | - David M. Aanensen
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Centre for Genomic Pathogen Surveillance, Wellcome Trust Sanger Institute, Cambridge, UK
| | - Simon R. Harris
- Centre for Genomic Pathogen Surveillance, Wellcome Trust Sanger Institute, Cambridge, UK
- Present address: Microbiotica Limited, Cambridge, UK
| | | | - Matthew T. G. Holden
- Centre for Genomic Pathogen Surveillance, Wellcome Trust Sanger Institute, Cambridge, UK
- University of St Andrews, St Andrews, UK
| | - Andrew S. Waller
- Animal Health Trust, Newmarket, UK
- Department of Biomedical Science and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
- Intervacc AB, Stockholm, Sweden
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Steward KF, Robinson C, Holden MTG, Harris SR, Ros AF, Pérez GC, Baselga R, Waller AS. Diversity of Streptococcus equi subsp. zooepidemicus strains isolated from the Spanish sheep and goat population and the identification, function and prevalence of a novel arbutin utilisation system. Vet Microbiol 2017; 207:231-238. [PMID: 28757029 DOI: 10.1016/j.vetmic.2017.06.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 06/27/2017] [Accepted: 06/28/2017] [Indexed: 01/01/2023]
Abstract
The zoonotic bacterium Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is a diverse, opportunistic pathogen that can cause mastitis in dairy sheep and goats. We used multilocus sequence typing (MLST) to define the genetic diversity of 60 isolates of S. zooepidemicus, which were recovered from sheep and goats in Spain between 2003 and 2010. We identify a novel clonal complex based on sequence type (ST), ST-236, which accounted for 39 of the 60 isolates. A representative ST-236 strain, S. zooepidemicus strain C7 (SzC7), was sequenced and interrogated for the presence of novel nutritional uptake or utilisation systems, the acquisition of which have previously been shown to be important for environmental adaptation in other streptococcal pathogens. A novel phosphoenolpyruvate sugar phosphotransferase system (PTS), which enabled the utilisation of arbutin, was identified. Functionality of the PTS was confirmed following deletion of the PTS from SzC7. Arbutin is found in multiple animal foodstuffs and we propose that the ability to utilise arbutin may have conferred a selective advantage to strains infecting animals, the diet of which contains this sugar.
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Affiliation(s)
- Karen F Steward
- Centre for Preventative Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, United Kingdom
| | - Carl Robinson
- Centre for Preventative Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, United Kingdom.
| | - Matthew T G Holden
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Simon R Harris
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Ana Fernández Ros
- Microbiology Department, Exopol, 50840 San Mateo de Gállego, Zaragoza, Spain
| | - Gema Chacón Pérez
- Microbiology Department, Exopol, 50840 San Mateo de Gállego, Zaragoza, Spain
| | - Rafael Baselga
- Microbiology Department, Exopol, 50840 San Mateo de Gállego, Zaragoza, Spain
| | - Andrew S Waller
- Centre for Preventative Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, United Kingdom
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Tirosh-Levy S, Blum SE, Steward KF, Waller AS, Steinman A. Streptococcus equi subspecies equi in horses in Israel: seroprevalence and strain types. Vet Rec Open 2016; 3:e000187. [PMID: 27651915 PMCID: PMC5013422 DOI: 10.1136/vetreco-2016-000187] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 07/20/2016] [Accepted: 07/22/2016] [Indexed: 11/04/2022] Open
Abstract
The purpose of this cross-sectional study was to determine the seroprevalence of Streptococcus equi in Israel, to monitor seropositive horses over time and to identify archived strains that were recovered from Israeli horses. A serological survey of 200 healthy horses on 20 farms throughout Israel was performed to detect recent exposure to S equi antigens A and C via indirect ELISA. Seroprevalence was 9.5 per cent (19/200) and positive horses were found in 30 per cent (6/20) of the farms. Sixteen horses that returned a positive serology result were retested three and six months later. Most (12/16) positive horses remained positive, which suggests the presence of animals with persistent infection. Molecular characterisation of S equi strains by sequencing of the SeM gene of 16 archived isolates of S equi that were recovered from clinical cases of strangles between 2008 and 2012 identified two strains: SeM-2 and SeM-28.
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Affiliation(s)
- S Tirosh-Levy
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem , Rehovot , Israel
| | - S E Blum
- Department of Bacteriology , Kimron Veterinary Institute , Bet Dagan , Israel
| | - K F Steward
- Centre for Preventive Medicine, Animal Health Trust , Newmarket, Suffolk , UK
| | - A S Waller
- Centre for Preventive Medicine, Animal Health Trust , Newmarket, Suffolk , UK
| | - A Steinman
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem , Rehovot , Israel
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Steward KF, Robinson C, Waller AS. Transcriptional changes are involved in phenotype switching in Streptococcus equi subspecies equi. Mol Biosyst 2016; 12:1194-200. [PMID: 26854112 DOI: 10.1039/c5mb00780a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Phenotypic heterogeneity within a population of bacteria, through genetic or transcriptional variation, enables survival and persistence in challenging and changing environments. We report here that a recent clinical isolate of S. equi, strain 1691 (Se1691), yielded a mixture of reduced capsule and mucoid colonies on primary isolation when grown on colistin-oxolinic acid blood agar (COBA) streptococcal selective plates. Passaging colonies of Se1691, with a reduced capsule phenotype maintained this mixed phenotype. In contrast, passaging mucoid colonies fixed the mucoid phenotype, suggesting adaptive genetic or transcriptional changes in response to growth on artificial media. However, despite obvious phenotypic and transcriptional differences, there were no apparent differences in the genome sequences of Se1691 recovered from colonies with a mucoid or reduced capsule phenotype. We identified 105 differentially transcribed genes in the transcriptomes of reduced capsule and mucoid colonies. The reduced capsule phenotype was associated with a significant reduction in transcription of the has locus (SEQ_0269 Q = 0.0015, SEQ_0270 Q = 0.0015, SEQ_0271 Q = 0.0285) and the amount of hyaluronic acid on the surface of S. equi recovered from non-mucoid colonies (P = 0.017). Significant differences in the transcription of 21 surface and secreted proteins were also observed. Our data show that changes in the bacterial transcriptome are linked to the mixed colony phenotype of Se1691.
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Affiliation(s)
- Karen F Steward
- Animal Health Trust, Kentford, NewmarketSuffolk, CB8 7UU, UK.
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Harris SR, Robinson C, Steward KF, Webb KS, Paillot R, Parkhill J, Holden MTG, Waller AS. Genome specialization and decay of the strangles pathogen, Streptococcus equi, is driven by persistent infection. Genome Res 2015; 25:1360-71. [PMID: 26160165 PMCID: PMC4561494 DOI: 10.1101/gr.189803.115] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 07/01/2015] [Indexed: 11/25/2022]
Abstract
Strangles, the most frequently diagnosed infectious disease of horses worldwide, is caused by Streptococcus equi. Despite its prevalence, the global diversity and mechanisms underlying the evolution of S. equi as a host-restricted pathogen remain poorly understood. Here, we define the global population structure of this important pathogen and reveal a population replacement in the late 19th or early 20th Century. Our data reveal a dynamic genome that continues to mutate and decay, but also to amplify and acquire genes despite the organism having lost its natural competence and become host-restricted. The lifestyle of S. equi within the horse is defined by short-term acute disease, strangles, followed by long-term infection. Population analysis reveals evidence of convergent evolution in isolates from post-acute disease samples as a result of niche adaptation to persistent infection within a host. Mutations that lead to metabolic streamlining and the loss of virulence determinants are more frequently found in persistent isolates, suggesting that the pathogenic potential of S. equi reduces as a consequence of long-term residency within the horse post-acute disease. An example of this is the deletion of the equibactin siderophore locus that is associated with iron acquisition, which occurs exclusively in persistent isolates, and renders S. equi significantly less able to cause acute disease in the natural host. We identify several loci that may similarly be required for the full virulence of S. equi, directing future research toward the development of new vaccines against this host-restricted pathogen.
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Affiliation(s)
- Simon R Harris
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, United Kingdom
| | - Carl Robinson
- The Animal Health Trust, Lanwades Park, Kentford, Newmarket CB8 7UU, United Kingdom
| | - Karen F Steward
- The Animal Health Trust, Lanwades Park, Kentford, Newmarket CB8 7UU, United Kingdom
| | - Katy S Webb
- The Animal Health Trust, Lanwades Park, Kentford, Newmarket CB8 7UU, United Kingdom
| | - Romain Paillot
- The Animal Health Trust, Lanwades Park, Kentford, Newmarket CB8 7UU, United Kingdom
| | - Julian Parkhill
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, United Kingdom
| | - Matthew T G Holden
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, United Kingdom; School of Medicine, University of St Andrews, North Haugh, St. Andrews KY16 9TF, United Kingdom
| | - Andrew S Waller
- The Animal Health Trust, Lanwades Park, Kentford, Newmarket CB8 7UU, United Kingdom
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Steward KF, Harrison T, Robinson C, Slater J, Maskell DJ, Harris SR, Holden MTG, Waller AS. PinR mediates the generation of reversible population diversity in Streptococcus zooepidemicus. Microbiology (Reading) 2015; 161:1105-1112. [PMID: 25701732 DOI: 10.1099/mic.0.000057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 02/10/2015] [Indexed: 11/18/2022]
Abstract
Opportunistic pathogens must adapt to and survive in a wide range of complex ecosystems. Streptococcus zooepidemicus is an opportunistic pathogen of horses and many other animals, including humans. The assembly of different surface architecture phenotypes from one genotype is likely to be crucial to the successful exploitation of such an opportunistic lifestyle. Construction of a series of mutants revealed that a serine recombinase, PinR, inverts 114 bp of the promoter of SZO_08560, which is bordered by GTAGACTTTA and TAAAGTCTAC inverted repeats. Inversion acts as a switch, controlling the transcription of this sortase-processed protein, which may enhance the attachment of S. zooepidemicus to equine trachea. The genome of a recently sequenced strain of S. zooepidemicus, 2329 (Sz2329), was found to contain a disruptive internal inversion of 7 kb of the FimIV pilus locus, which is bordered by TAGAAA and TTTCTA inverted repeats. This strain lacks pinR and this inversion may have become irreversible following the loss of this recombinase. Active inversion of FimIV was detected in three strains of S. zooepidemicus, 1770 (Sz1770), B260863 (SzB260863) and H050840501 (SzH050840501), all of which encoded pinR. A deletion mutant of Sz1770 that lacked pinR was no longer capable of inverting its internal region of FimIV. The data highlight redundancy in the PinR sequence recognition motif around a short TAGA consensus and suggest that PinR can reversibly influence the wider surface architecture of S. zooepidemicus, providing this organism with a bet-hedging solution to survival in fluctuating environments.
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Affiliation(s)
| | | | - Carl Robinson
- Animal Health Trust, Kentford, Newmarket CB8 7UU, UK
| | - Josh Slater
- Royal Veterinary College, Hawkshead Lane, Hatfield AL9 7TA, UK
| | - Duncan J Maskell
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 OES, UK
| | - Simon R Harris
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton CB10 1SA, UK
| | - Matthew T G Holden
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton CB10 1SA, UK
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Robinson C, Heather Z, Slater J, Potts N, Steward KF, Maskell DJ, Fontaine MC, Lee JJ, Smith K, Waller AS. Vaccination with a live multi-gene deletion strain protects horses against virulent challenge with Streptococcus equi. Vaccine 2015; 33:1160-7. [PMID: 25597942 DOI: 10.1016/j.vaccine.2015.01.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 01/05/2015] [Accepted: 01/06/2015] [Indexed: 10/24/2022]
Abstract
Strangles, caused by Streptococcus equi subspecies equi (S. equi) is one of the most frequently diagnosed infectious diseases of horses and there remains a significant need to develop new preventative vaccines. We generated a live vaccine strain of S. equi containing deletions in six genes: sagA, hasA, aroB, pyrC, seM and recA, which was administered to nine Welsh mountain ponies via the intramuscular route. Four vaccinated ponies developed adverse reactions following the first vaccination from which the live vaccine strain was isolated. Two of these ponies were withdrawn from the study and seven ponies received a second vaccination, one of which then developed an adverse reaction. Nine control ponies injected with culture media alone developed no adverse reactions. Following challenge with a virulent strain of S. equi, none of the seven vaccinated ponies had developed clinical signs of strangles eleven days post-challenge, compared to six of nine control ponies over the same period (P=0.0114). A lymph node abscess was identified in one of the seven vaccinated ponies at post-mortem examination, whilst all nine control ponies had at least one lymph node abscess (P=0.0009). Three of the six vaccinated ponies that were protected from strangles had not developed an adverse reaction following vaccination, suggesting that a better understanding of the pro-inflammatory responses to S. equi could lead to the development of a live attenuated vaccine against strangles that is safe for administration via intramuscular injection.
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Affiliation(s)
- Carl Robinson
- Animal Health Trust, Lanwades Park, Kentford, Newmarket CB8 7UU, United Kingdom
| | - Zoe Heather
- Animal Health Trust, Lanwades Park, Kentford, Newmarket CB8 7UU, United Kingdom
| | - Josh Slater
- Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Herts AL9 7TA, United Kingdom
| | - Nicola Potts
- Animal Health Trust, Lanwades Park, Kentford, Newmarket CB8 7UU, United Kingdom
| | - Karen F Steward
- Animal Health Trust, Lanwades Park, Kentford, Newmarket CB8 7UU, United Kingdom
| | - Duncan J Maskell
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 OES, United Kingdom
| | - Michael C Fontaine
- Institute for Cell and Molecular Biosciences, The Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Jeong-Jin Lee
- Institute for Cell and Molecular Biosciences, The Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Ken Smith
- Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Herts AL9 7TA, United Kingdom
| | - Andrew S Waller
- Animal Health Trust, Lanwades Park, Kentford, Newmarket CB8 7UU, United Kingdom.
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Robinson C, Steward KF, Potts N, Barker C, Hammond TA, Pierce K, Gunnarsson E, Svansson V, Slater J, Newton JR, Waller AS. Combining two serological assays optimises sensitivity and specificity for the identification of Streptococcus equi subsp. equi exposure. Vet J 2013; 197:188-91. [DOI: 10.1016/j.tvjl.2013.01.033] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 01/25/2013] [Accepted: 01/29/2013] [Indexed: 11/29/2022]
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Webb K, Barker C, Harrison T, Heather Z, Steward KF, Robinson C, Newton JR, Waller AS. Detection of Streptococcus equi subspecies equi using a triplex qPCR assay. Vet J 2012; 195:300-4. [PMID: 22884566 PMCID: PMC3611602 DOI: 10.1016/j.tvjl.2012.07.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 06/12/2012] [Accepted: 07/07/2012] [Indexed: 12/04/2022]
Abstract
Genome sequencing data for Streptococcus equi subspecies equi and zooepidemicus were used to develop a novel diagnostic triplex quantitative PCR (qPCR) assay targeting two genes specific to S. equi (eqbE and SEQ2190) and a unique 100 base pair control DNA sequence (SZIC) inserted into the SZO07770 pseudogene of S. zooepidemicus strain H70. This triplex strangles qPCR assay can provide results within 2 h of sample receipt, has an overall sensitivity of 93.9% and specificity of 96.6% relative to the eqbE singlex assay and detects S. equi at levels below the threshold of the culture assay, even in the presence of contaminating bacteria.
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Affiliation(s)
- Katy Webb
- Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU, UK
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Holden MTG, Heather Z, Paillot R, Steward KF, Webb K, Ainslie F, Jourdan T, Bason NC, Holroyd NE, Mungall K, Quail MA, Sanders M, Simmonds M, Willey D, Brooks K, Aanensen DM, Spratt BG, Jolley KA, Maiden MCJ, Kehoe M, Chanter N, Bentley SD, Robinson C, Maskell DJ, Parkhill J, Waller AS. Genomic evidence for the evolution of Streptococcus equi: host restriction, increased virulence, and genetic exchange with human pathogens. PLoS Pathog 2009; 5:e1000346. [PMID: 19325880 PMCID: PMC2654543 DOI: 10.1371/journal.ppat.1000346] [Citation(s) in RCA: 171] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Accepted: 02/24/2009] [Indexed: 11/19/2022] Open
Abstract
The continued evolution of bacterial pathogens has major implications for both human and animal disease, but the exchange of genetic material between host-restricted pathogens is rarely considered. Streptococcus equi subspecies equi (S. equi) is a host-restricted pathogen of horses that has evolved from the zoonotic pathogen Streptococcus equi subspecies zooepidemicus (S. zooepidemicus). These pathogens share approximately 80% genome sequence identity with the important human pathogen Streptococcus pyogenes. We sequenced and compared the genomes of S. equi 4047 and S. zooepidemicus H70 and screened S. equi and S. zooepidemicus strains from around the world to uncover evidence of the genetic events that have shaped the evolution of the S. equi genome and led to its emergence as a host-restricted pathogen. Our analysis provides evidence of functional loss due to mutation and deletion, coupled with pathogenic specialization through the acquisition of bacteriophage encoding a phospholipase A2 toxin, and four superantigens, and an integrative conjugative element carrying a novel iron acquisition system with similarity to the high pathogenicity island of Yersinia pestis. We also highlight that S. equi, S. zooepidemicus, and S. pyogenes share a common phage pool that enhances cross-species pathogen evolution. We conclude that the complex interplay of functional loss, pathogenic specialization, and genetic exchange between S. equi, S. zooepidemicus, and S. pyogenes continues to influence the evolution of these important streptococci. Streptococci colonize a diverse range of animals and tissues, and this association is normally harmless. Occasionally some strains of streptococci have an increased ability to cause disease that is often associated with a reduction in the ability to colonize and the acquisition of new genes, which enable the strain to inhabit a new niche. S. equi is the causative agent of strangles, one of the most frequently diagnosed and feared infectious diseases of horses, which is believed to have evolved from the closely related and usually harmless S. zooepidemicus. We aim to understand the mechanisms by which S. equi causes disease by studying and comparing the genomes of these different strains. Here we identify specific genes that have been lost and gained by S. equi, which may have directed its transition from colonizer to invader. Several of the novel genes acquired by S. equi have also been identified in strains of the closely related bacterium S. pyogenes that are associated with increased morbidity and mortality in humans. Our research highlights the role of genetic exchange in cross-species bacterial evolution and argues that the evolution of human pathogens cannot be considered in isolation.
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Affiliation(s)
- Matthew T. G. Holden
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Zoe Heather
- Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, United Kingdom
| | - Romain Paillot
- Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, United Kingdom
| | - Karen F. Steward
- Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, United Kingdom
| | - Katy Webb
- Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, United Kingdom
| | - Fern Ainslie
- Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, United Kingdom
| | - Thibaud Jourdan
- Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, United Kingdom
| | - Nathalie C. Bason
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Nancy E. Holroyd
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Karen Mungall
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Michael A. Quail
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Mandy Sanders
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Mark Simmonds
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - David Willey
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Karen Brooks
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - David M. Aanensen
- Department of Infectious Disease Epidemiology, Imperial College London, St. Mary's Hospital Campus, London, United Kingdom
| | - Brian G. Spratt
- Department of Infectious Disease Epidemiology, Imperial College London, St. Mary's Hospital Campus, London, United Kingdom
| | - Keith A. Jolley
- The Peter Medawar Building for Pathogen Research and Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Martin C. J. Maiden
- The Peter Medawar Building for Pathogen Research and Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Michael Kehoe
- Institute for Cell and Molecular Biosciences, The Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom
| | - Neil Chanter
- Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, United Kingdom
| | - Stephen D. Bentley
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Carl Robinson
- Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, United Kingdom
| | - Duncan J. Maskell
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Julian Parkhill
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Andrew S. Waller
- Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, United Kingdom
- * E-mail:
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Heather Z, Holden MTG, Steward KF, Parkhill J, Song L, Challis GL, Robinson C, Davis-Poynter N, Waller AS. A novel streptococcal integrative conjugative element involved in iron acquisition. Mol Microbiol 2009; 70:1274-92. [PMID: 18990191 PMCID: PMC3672683 DOI: 10.1111/j.1365-2958.2008.06481.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In this study, we determined the function of a novel non-ribosomal peptide synthetase (NRPS) system carried by a streptococcal integrative conjugative element (ICE), ICESe2. The NRPS shares similarity with the yersiniabactin system found in the high-pathogenicity island of Yersinia sp. and is the first of its kind to be identified in streptococci. We named the NRPS product 'equibactin' and genes of this locus eqbA-N. ICESe2, although absolutely conserved in Streptococcus equi, the causative agent of equine strangles, was absent from all strains of the closely related opportunistic pathogen Streptococcus zooepidemicus. Binding of EqbA, a DtxR-like regulator, to the eqbB promoter was increased in the presence of cations. Deletion of eqbA resulted in a small-colony phenotype. Further deletion of the irp2 homologue eqbE, or the genes eqbH, eqbI and eqbJ encoding a putative ABC transporter, or addition of the iron chelator nitrilotriacetate, reversed this phenotype, implicating iron toxicity. Quantification of (55)Fe accumulation and sensitivity to streptonigrin suggested that equibactin is secreted by S. equi and that the eqbH, eqbI and eqbJ genes are required for its associated iron import. In agreement with a structure-based model of equibactin synthesis, supplementation of chemically defined media with salicylate was required for equibactin production.
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Affiliation(s)
- Zoe Heather
- Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, UK
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