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Jiang X, Ma X, Su L, Zhang B, He Z, Su Y. Analysis of distinct variants of immunoglobulin G binding protein EAG on humoral immunity and bacterial clearance of Streptococcus equi subspecies equi. Microb Pathog 2025; 205:107726. [PMID: 40409431 DOI: 10.1016/j.micpath.2025.107726] [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: 03/03/2025] [Revised: 04/30/2025] [Accepted: 05/19/2025] [Indexed: 05/25/2025]
Abstract
OBJECTIVE Streptococcus equi subspecies equi (S. equi) causes strangles, one of the most prevalent and highly contagious equine infectious diseases with significant welfare and economic impacts. Alpha 2-macroglobulin and immunoglobulin G binding protein (EAG) has been identified as a key antigen and plays a crucial role in the immune evasion of S. equi. In this study, we aimed to investigate the genetic polymorphism of EAG and to determine the effects of genetic variation on its function and immunogenicity. METHODS Phylogenetic analysis indicated these EAG mutants belong to two clades, respectively. Three recombinant EAG mutants-EAG5012 (K123E and 155-169), EAG823 (A73V), and EAGHT1112 (T196I)-were expressed and purified. A mouse model and equine were then used to evaluate the immunogenicity and protection efficacy of these mutants. Antibody levels, phagocytosis inhibition, and opsonophagocytosis were assayed. RESULTS Our results showed that the EAG5012 mutant elicited the highest levels of specific immunoglobulin G (IgG), IgG1, and IgG2a, protecting immunized mice against intraperitoneal challenge of three different S. equi strains, with a protection rate of 80 %-86.7 %. Additionally, the EAG5012 mutant exhibited significantly enhanced phagocytic inhibition, and its antisera showed increased opsonophagocytic activity. Conversely, the EAG823 mutant displayed the lowest IgG levels, opsonophagocytic capability, and protection rate (66.7 %-73 %). The results suggest that the variations located at K123E and 155-169 in the EAG5012 mutant are significantly affected the opsonophagocytic activity of PMNs. CONCLUSION The conformational epitope altered by these variations significantly impacts IgG immune responses and antibody-mediated opsonophagocytic activity. Our findings may be useful for the future development of effective multivalent subunit vaccines against strangles.
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Affiliation(s)
- Xinyu Jiang
- Department of Microbiology and Immunology, College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, Xinjiang, 830052, China
| | - Xiaohui Ma
- Department of Microbiology and Immunology, College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, Xinjiang, 830052, China
| | - Lingling Su
- Xinjiang Academy of Animal Science, Urumqi, Xinjiang, 830000, China
| | - Baojiang Zhang
- Department of Microbiology and Immunology, College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, Xinjiang, 830052, China
| | - Zehang He
- Department of Microbiology and Immunology, College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, Xinjiang, 830052, China
| | - Yan Su
- Department of Microbiology and Immunology, College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, Xinjiang, 830052, China.
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Seeger MG, Correa DC, Barcelos RAD, Werle J, Masuda EK, Bordin AI, Cohen ND, Vogel FSF, Cargnelutti JF. Variation in SeM genotype is associated with virulence of Streptococcus equi subspecies equi in mice. Microb Pathog 2025; 205:107541. [PMID: 40203958 DOI: 10.1016/j.micpath.2025.107541] [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: 11/06/2024] [Revised: 03/07/2025] [Accepted: 04/02/2025] [Indexed: 04/11/2025]
Abstract
Strangles is a common infectious disease caused by Streptococcus equi subspecies equi (S. equi) that primarily affects the upper respiratory system. To date, 271 alleles of the M protein (seM) have been identified that may be related to antigenic differences of isolates. This study evaluated the virulence of S. equi isolates from different alleles of the M protein in an experimental mouse model. Thirty-six Swiss mice were allocated into 12 groups (G1-G12) and each infected group received a different isolate of S. equi recovered from horses with strangles: G1: seM-117; G2: seM-61; G3: seM-123; G4: seM-115; G5: seM-271; G6: seM-124; G7: seM-158, and G8: seM-39, G9: no allele, G10: seM-28, G11: control (no infection - Brazil), G12: control (no infection - Texas). Mice were infected intranasally with 2 × 106 CFU/mL and monitored for clinical signs, weight, and nasal culture over 10 days. Clinical signs varied among mice inoculated with different isolates of S. equi, ranging from lethargy, serous ocular discharge, and rhinitis to tachypnea and neurological alterations. Isolates from alleles seM-158 (G7), seM-39 (G8), and seM-271 (G5) were classified as highly virulent, frequently resulting in death or euthanasia, along with consistent bacterial excretion and enlargement of lymph nodes. Mice in G4 (seM-115), G6 (seM-124), G9 (no allele), and G10 (seM-28) showed moderately severe clinical signs of disease, whereas clinical signs for mice in G1 (seM-117), G2 (seM-61), and G3 (seM-123) were mild or absent. Results demonstrate that isolates of S. equi with different M protein alleles exhibit varying levels of virulence in mice, ranging from asymptomatic infection to severe illness and mortality. Additional investigations should be conducted to assess whether virulence in horses is associated with S. equi M protein variability and whether the association of M protein genotype with virulence is causal.
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Affiliation(s)
- Marlane Geribone Seeger
- Programa de Pós-Graduação em Medicina Veterinária, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Diego Cristiano Correa
- Programa de Pós-Graduação em Medicina Veterinária, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | | | - Júlia Werle
- Programa de Pós-Graduação em Medicina Veterinária, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Eduardo Kenji Masuda
- Laboratório Axys Análises Diagnóstico Veterinário e Consultoria, Alberto Silva, 332, Porto Alegre, RS, 91370-000, Brazil
| | - Angela Ilha Bordin
- Departmento de Ciências Clínicas de Grandes Animais, Texas A&M School of Veterinary Medicine & Biomedical Sciences, 4475 TAMU, College Station, TX, 77843-4475, USA
| | - Noah D Cohen
- Departmento de Ciências Clínicas de Grandes Animais, Texas A&M School of Veterinary Medicine & Biomedical Sciences, 4475 TAMU, College Station, TX, 77843-4475, USA
| | | | - Juliana Felipetto Cargnelutti
- Departamento de Medicina Veterinária Preventiva (DMVP), Centro de Ciências Rurais (CCR), UFSM, Santa Maria, RS, Brazil.
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Frosth S, Morris ERA, Wilson H, Frykberg L, Jacobsson K, Parkhill J, Flock JI, Wood T, Guss B, Aanensen DM, Boyle AG, Riihimäki M, Cohen ND, Waller AS. Conservation of vaccine antigen sequences encoded by sequenced strains of Streptococcus equi subsp. equi. Equine Vet J 2023; 55:92-101. [PMID: 35000217 PMCID: PMC10078666 DOI: 10.1111/evj.13552] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 12/08/2021] [Accepted: 12/30/2021] [Indexed: 12/16/2022]
Abstract
BACKGROUND Streptococcus equi subspecies equi (S equi) is the cause of Strangles, one of the most prevalent diseases of horses worldwide. Variation within the immunodominant SeM protein has been documented, but a new eight-component fusion protein vaccine, Strangvac, does not contain live S equi or SeM and conservation of the antigens it contains have not been reported. OBJECTIVE To define the diversity of the eight Strangvac antigens across a diverse S equi population. STUDY DESIGN Genomic description. METHODS Antigen sequences from the genomes of 759 S equi isolates from 19 countries, recovered between 1955 and 2018, were analysed. Predicted amino acid sequences in the antigen fragments of SEQ0256(Eq5), SEQ0402(Eq8), SEQ0721(EAG), SEQ0855(SclF), SEQ0935(CNE), SEQ0999(IdeE), SEQ1817(SclI) and SEQ2101(SclC) in Strangvac and SeM were extracted from the 759 assembled genomes and compared. RESULTS The predicted amino acid sequences of SclC, SclI and IdeE were identical across all 759 genomes. CNE was truncated in the genome of five (0.7%) isolates. SclF was absent from one genome and another encoded a single amino acid substitution. EAG was truncated in two genomes. Eq5 was truncated in four genomes and 123 genomes encoded a single amino acid substitution. Eq8 was truncated in three genomes, one genome encoded four amino acid substitutions and 398 genomes encoded a single amino acid substitution at the final amino acid of the Eq8 antigen fragment. Therefore, at least 1579 (99.9%) of 1580 amino acids in Strangvac were identical in 743 (97.9%) genomes, and all genomes encoded identical amino acid sequences for at least six of the eight Strangvac antigens. MAIN LIMITATIONS Three hundred and seven (40.4%) isolates in this study were recovered from horses in the UK. CONCLUSIONS The predicted amino acid sequences of antigens in Strangvac were highly conserved across this collection of S equi.
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Affiliation(s)
- Sara Frosth
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Ellen Ruth A Morris
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, Texas, USA
| | | | - Lars Frykberg
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Karin Jacobsson
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | | | - Jan-Ingmar Flock
- Department of Microbiology, Tumour and Cell Biology, Karolinska Institutet, Stockholm, Sweden.,Intervacc AB, Stockholm, Sweden
| | | | - Bengt Guss
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - David M Aanensen
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Ashley G Boyle
- Department of Clinical Studies New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Miia Riihimäki
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Noah D Cohen
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, Texas, USA
| | - Andrew S Waller
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden.,Intervacc AB, Stockholm, Sweden
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Xu S, Liu Y, Gao J, Zhou M, Yang J, He F, Kastelic JP, Deng Z, Han B. Comparative Genomic Analysis of Streptococcus dysgalactiae subspecies dysgalactiae Isolated From Bovine Mastitis in China. Front Microbiol 2021; 12:751863. [PMID: 34745056 PMCID: PMC8570283 DOI: 10.3389/fmicb.2021.751863] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 09/24/2021] [Indexed: 12/11/2022] Open
Abstract
Streptococcus dysgalactiae subsp. dysgalactiae (SDSD) is one of the most prevalent pathogens causing bovine mastitis worldwide. However, there is a lack of comprehensive information regarding genetic diversity, complete profiles of virulence factors (VFs), and antimicrobial resistance (AMR) genes for SDSD associated with bovine mastitis in China. In this study, a total of 674 milk samples, including samples from 509 clinical and 165 subclinical mastitis cases, were collected from 17 herds in 7 provinces in China from November 2016 to June 2019. All SDSD isolates were included in phylogenetic analysis based on 16S rRNA and multi-locus sequence typing (MLST). In addition, whole genome sequencing was performed on 12 representative SDSD isolates to screen for VFs and AMR genes and to define pan-, core and accessory genomes. The prevalence of SDSD from mastitis milk samples was 7.57% (51/674). According to phylogenetic analysis based on 16S rRNA, 51 SDSD isolates were divided into 4 clusters, whereas based on MLST, 51 SDSD isolates were identified as 11 sequence types, including 6 registered STs and 5 novel STs (ST521, ST523, ST526, ST527, ST529) that belonged to 2 distinct clonal complexes (CCs) and 4 singletons. Based on WGS information, 108 VFs genes in 12 isolates were determined in 11 categories. In addition, 23 AMR genes were identified in 11 categories. Pan-, core and accessory genomes were composed of 2,663, 1,633 and 699 genes, respectively. These results provided a comprehensive profiles of SDSD virulence and resistance genes as well as phylogenetic relationships among mastitis associated SDSD in North China.
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Affiliation(s)
- Siyu Xu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Yang Liu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Jian Gao
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Man Zhou
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Jingyue Yang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Fumeng He
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - John P Kastelic
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Zhaoju Deng
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Bo Han
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China
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5
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Durham AE, Kemp-Symonds J. Failure of serological testing for antigens A and C of Streptococcus equi subspecies equi to identify guttural pouch carriers. Equine Vet J 2020; 53:38-43. [PMID: 32374892 DOI: 10.1111/evj.13276] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 04/05/2020] [Accepted: 04/23/2020] [Indexed: 01/08/2023]
Abstract
BACKGROUND Serology is commonly used as a means of identifying horses that might be chronic and silent carriers of S. equi but its sensitivity is rarely examined. OBJECTIVES The study was designed to investigate the sensitivity of serological testing for antibodies against S. equi antigens A and C to detect guttural pouch carriers of S. equi. STUDY DESIGN Retrospective clinical study. METHODS As part of routine surveillance and quarantine procedures horses arriving at a welfare charity quarantine unit were subject to both microbiological sampling of guttural pouches and also serological testing for antibodies directed at S. equi antigens A and C. Laboratory results and endoscopic findings were examined to determine associations between serological results and guttural pouch carriage of S. equi. RESULTS Of 287 included horses, 9 (3.1%) were found to be guttural pouch carriers. There was no significant association between serological status and guttural pouch carriage of S. equi Only one of the nine carriers (11%) was seropositive using a cut-off of OD ≥ 0.5, and only three of nine (33%) using a cut-off of OD ≥ 0.3. MAIN LIMITATIONS Horses examined in this study were new arrivals at a welfare centre rather than from a general, well-managed, equid population. As a retrospective clinical study, the laboratory test results could not be repeated for further confirmation. CONCLUSIONS Caution is advised when relying on seronegativity to antigens A and C in order to discount the possibility of chronic carriage of S. equi in guttural pouches.
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Tartor YH, El-Naenaeey ESY, Gharieb NM, Ali WS, Ammar AM. Novel Streptococcus equi strains causing strangles outbreaks in Arabian horses in Egypt. Transbound Emerg Dis 2020; 67:2455-2466. [PMID: 32304282 DOI: 10.1111/tbed.13584] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 04/04/2020] [Accepted: 04/06/2020] [Indexed: 11/28/2022]
Abstract
Strangles displays a major challenge to veterinary medicine worldwide. However, no data on Streptococcus equi subsp. equi (S. equi) M protein alleles have been reported so far from Arabian horses. We report here for the first time the S. equi SeM alleles causing strangles in Arabian horses, and the associated risk factors for the disease. Duplicate samples from one hundred Arabian horses with acute strangles in confirmed outbreaks and sporadic cases were analysed by phenotypic methods and multiplex polymerase chain reaction (PCR) targeting streptokinase precursor, seeI and sodA genes. PCR and sequencing of S. equi SeM gene were employed for strains typing, and the four superantigens were determined among the allelic variants. Direct-sample PCR confirmed and highly positively correlated (r = .85) with the phenotypic results, and detected S. equi in five samples more than the conventional culture. A combination of multiplex PCR from samples and culture could successfully identify S. equi (92%), S. zooepidemicus (5%) and S. equisimilis (3%). SeM typing demonstrated five SeM alleles, including four previously unidentified alleles that were deposited in the PubMLST-SeM database. SeM-139 and SeM-141 are related to some strains that were recently recovered from donkeys in China. SeM-140 and SeM-199 are related to a group of alleles from horses in Europe. Variation in the presence of seeM, seeH and seeL superantigens was found across the four novel alleles without interference with the severity of strangles and clinical presentation seen in different outbreaks. Horse age was the most important factor in developing strangles, followed by seasonality and the diagnosis of strangles in the previous year. These new findings comprise a significant contribution to the horse industry through the identification of novel S. equi SeM types that may bolster measures for strangles control as the identified SeM alleles will certainly help in the development of SeM-containing vaccine.
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Affiliation(s)
- Yasmine H Tartor
- Department of Microbiology, Faculty of Veterinary Medicine, Zagazig University, Zagazig, 44511, Egypt
| | - El-Sayed Y El-Naenaeey
- Department of Microbiology, Faculty of Veterinary Medicine, Zagazig University, Zagazig, 44511, Egypt
| | - Nesreen M Gharieb
- Department of Animal Management and Treatment, Kafr Saqr Veterinary Administration, Sharkia Governorate, Zagazig, Egypt
| | - Wessam S Ali
- Department of Animal Management and Treatment, Diarb Negm Veterinary Administration, Sharkia Governorate, Zagazig, Egypt
| | - Ahmed M Ammar
- Department of Microbiology, Faculty of Veterinary Medicine, Zagazig University, Zagazig, 44511, Egypt
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Dong J, Gao N, Waller AS, Cook FR, Fan S, Yuan D, Du Y, Li F, Norimine J, Zhu W. An outbreak of strangles associated with a novel genotype of Streptococcus equi subspecies equi in donkeys in China during 2018. Equine Vet J 2019; 51:743-748. [PMID: 30900775 DOI: 10.1111/evj.13114] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 03/15/2019] [Indexed: 11/30/2022]
Abstract
BACKGROUND Strangles is a highly contagious respiratory disease of equids caused by the bacterium Streptococcus equi subspecies equi. OBJECTIVES To identify the cause of an outbreak of strangles that occurred on donkey farms within the Shandong Province of China and determine the prevalence of the disease. STUDY DESIGN Cross-sectional. METHODS Samples were taken from clinically affected animals to measure the prevalence of strangles within the population of donkeys at six intensive farms in China and identify the SeM type of isolate recovered from affected animals. Diagnosis was confirmed by bacterial isolation, biochemical tests and PCR. Epidemiological data were analysed using Chi-square test and a Fisher's exact two-sided test. The SeM gene of S. equi isolates recovered from affected animals was determined and compared with the SeM database PubMLST-seM. RESULTS In July and August 2018, an outbreak of strangles occurred on six donkey farms within the Shandong Province of China. The overall prevalence of disease within the different donkey herds was 13.4%. Younger animals were worst affected with 40.3% (83/206) of donkey foals aged under 1 year exhibiting clinical signs compared with 12.5% (191/1525) of donkeys aged one to 2 years and 3.8% (17/442) of donkeys over 2 years of age. Analysis of SeM sequencing data identified that the farms were affected by the same strain of S. equi, SD201807, which contains the novel 136 allele of SeM. MAIN LIMITATIONS Healthy donkeys were not sampled in this study. CONCLUSIONS The number of intensive donkey breeding farms in China has risen recently. The higher numbers of animals that are in closer proximity to one another raise the potential for the transmission of infectious diseases such as strangles. This is the first description of a strangles outbreak among donkey herds in China. The Summary is available in Chinese - see Supporting information.
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Affiliation(s)
- J Dong
- Department of Veterinary Medical Science, Shandong Vocational Animal Science and Veterinary College, Weifang, China.,Shandong Donkey Industry Technology Collaborative Innovation Center, College of Agronomy, Liaocheng University, Liaocheng, China.,Center for Animal Disease Control, University of Miyazaki, Miyazaki, Japan
| | - N Gao
- Department of Veterinary Medical Science, Shandong Vocational Animal Science and Veterinary College, Weifang, China
| | | | - F R Cook
- Department of Veterinary Science, Gluck Equine Research Center, University of Kentucky, Lexington, Kentucky, USA
| | - S Fan
- Department of Veterinary Medical Science, Shandong Vocational Animal Science and Veterinary College, Weifang, China
| | - D Yuan
- Department of Veterinary Medical Science, Shandong Vocational Animal Science and Veterinary College, Weifang, China
| | - Y Du
- Department of Veterinary Medical Science, Shandong Vocational Animal Science and Veterinary College, Weifang, China
| | - F Li
- Department of Veterinary Medical Science, Shandong Vocational Animal Science and Veterinary College, Weifang, China
| | - J Norimine
- Center for Animal Disease Control, University of Miyazaki, Miyazaki, Japan
| | - W Zhu
- Department of Veterinary Medical Science, Shandong Vocational Animal Science and Veterinary College, Weifang, China.,Shandong Donkey Industry Technology Collaborative Innovation Center, College of Agronomy, Liaocheng University, Liaocheng, China
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Tonpitak W, Sornklien C, Wutthiwithayaphong S. Characterization of a Streptococcus equi ssp. equi Isolate From a Strangles Outbreak in Thailand. J Equine Vet Sci 2016. [DOI: 10.1016/j.jevs.2016.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Comparison of specificities of serum antibody responses of horses to clinical infections caused by Streptococcus equi or zooepidemicus. Vet Microbiol 2015; 180:253-9. [DOI: 10.1016/j.vetmic.2015.09.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 09/04/2015] [Accepted: 09/09/2015] [Indexed: 11/20/2022]
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B-cell-specific peptides of leptospira interrogans LigA for diagnosis of patients with acute leptospirosis. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2014; 21:354-9. [PMID: 24403522 DOI: 10.1128/cvi.00456-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Leptospirosis is a reemerging infectious disease that is underdiagnosed and under-recognized due to low-sensitivity and cumbersome serological tests. Rapid reliable alternative tests are needed for early diagnosis of the disease. Considering the importance of the pathogenesis-associated leptospiral LigA protein expressed in vivo, we have evaluated its application in the diagnosis of the acute form of leptospirosis. The C-terminal coding sequence of ligA (ligA-C) was cloned into pET15b and expressed in Escherichia coli. Furthermore, the B-cell-specific epitopes were predicted and were synthesized as peptides for evaluation along with recombinant LigA-C. Epitope 1 (VVIENTPGK), with a VaxiJen score of 1.3782, and epitope 2 (TALSVGSSK), with a score of 1.2767, were utilized. A total of 140 serum samples collected from leptospirosis cases during the acute stage of the disease and 138 serum samples collected from normal healthy controls were utilized for evaluation. The sensitivity, specificity, positive predictive value, and negative predictive value were calculated for the recombinant LigA-C-specific IgM enzyme-linked immunosorbent assay (ELISA) and were found to be 92.1%, 97.7%, 92.8%, and 97.5%, respectively. Epitopes 1 and 2 used in the study showed 5.1 to 5.8% increased sensitivity over recombinant LigA-C in single and combination assays for IgM antibody detection. These findings suggest that these peptides may be potential candidates for the early diagnosis of leptospirosis.
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Characterization and protective immunogenicity of the SzM protein of Streptococcus zooepidemicus NC78 from a clonal outbreak of equine respiratory disease. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2013; 20:1181-8. [PMID: 23740925 DOI: 10.1128/cvi.00069-13] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Streptococcus zooepidemicus of Lancefield group C is a highly variable tonsillar and mucosal commensal that usually is associated with opportunistic infections of the respiratory tract of vertebrate hosts. More-virulent clones have caused epizootics of severe respiratory disease in dogs and horses. The virulence factors of these strains are poorly understood. The antiphagocytic protein SeM is a major virulence factor and protective antigen of Streptococcus equi, a clonal biovar of an ancestral S. zooepidemicus strain. Although the genome of S. zooepidemicus strain H70, an equine isolate, contains a partial homolog (szm) of sem, expression of the gene has not been documented. We have identified and characterized SzM from an encapsulated S. zooepidemicus strain from an epizootic of equine respiratory disease in New Caledonia. The SzM protein of strain NC78 (SzM(NC78)) has a predicted predominantly alpha-helical fibrillar structure with an LPSTG cell surface anchor motif and resistance to hot acid. A putative binding site for plasminogen is present in the B repeat region, the sequence of which shares homology with repeats of the plasminogen binding proteins of human group C and G streptococci. Equine plasminogen is activated in a dose-dependent manner by recombinant SzM(NC78). Only 23.20 and 25.46% DNA homology is shared with SeM proteins of S. equi strains CF32 and 4047, respectively, and homology ranges from 19.60 to 54.70% for SzM proteins of other S. zooepidemicus strains. As expected, SzM(NC78) reacted with convalescent-phase sera from horses with respiratory disease associated with strains of S. zooepidemicus. SzM(NC78) resembles SeM in binding equine fibrinogen and eliciting strong protective antibody responses in mice. Sera of vaccinated mice opsonized S. zooepidemicus strains NC78 and W60, the SzM protein of which shared partial amino acid homology with SzM(NC78). We conclude that SzM is a protective antigen of NC78; it was strongly reactive with serum antibodies from horses during recovery from S. zooepidemicus-associated respiratory disease.
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Moloney E, Kavanagh KS, Buckley TC, Cooney JC. Lineages of Streptococcus equi ssp. equi in the Irish equine industry. Ir Vet J 2013; 66:10. [PMID: 23731628 PMCID: PMC3679875 DOI: 10.1186/2046-0481-66-10] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 05/24/2013] [Indexed: 11/19/2022] Open
Abstract
Background Streptococcus equi ssp. equi is the causative agent of ‘Strangles’ in horses. This is a debilitating condition leading to economic loss, yard closures and cancellation of equestrian events. There are multiple genotypes of S. equi ssp. equi which can cause disease, but to date there has been no systematic study of strains which are prevalent in Ireland. This study identified and classified Streptococcus equi ssp. equi strains isolated from within the Irish equine industry. Results Two hundred veterinary isolates were subjected to SLST (single locus sequence typing) based on an internal sequence from the seM gene of Streptococcus equi ssp equi. Of the 171 samples which successfully gave an amplicon, 162 samples (137 Irish and 24 UK strains) gave robust DNA sequence information. Analysis of the sequences allowed division of the isolates into 19 groups, 13 of which contain at least 2 isolates and 6 groups containing single isolates. There were 19 positions where a DNA SNP (single nucleotide polymorphism) occurs, and one 3 bp insertion. All groups had multiple (2–8) SNPs. Of the SNPs 17 would result in an amino acid change in the encoded protein. Interestingly, the single isolate EI8, which has 6 SNPs, has the three base pair insertion which is not seen in any other isolate, this would result in the insertion of an Ile residue at position 62 in that protein sequence. Comparison of the relevant region in the determined sequences with the UK Streptococcus equi seM MLST database showed that Group B (15 isolates) and Group I (2 isolates), as well as the individual isolates EI3 and EI8, are unique to Ireland, and some groups are most likely of UK origin (Groups F and M), but many more probably passed back and forth between the two countries. Conclusions The strains occurring in Ireland are not clonal and there is a considerable degree of sequence variation seen in the seM gene. There are two major clades causing infection in Ireland and these strains are also common in the UK.
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Affiliation(s)
- Emma Moloney
- Department of Life Sciences, University of Limerick, Limerick, Ireland
| | | | - Tom C Buckley
- Irish Equine Centre, Johnstown, Naas, Co. Kildare, Ireland
| | - Jakki C Cooney
- Department of Life Sciences, University of Limerick, Limerick, Ireland ; Materials and Surface Sciences Institute, University of Limerick, Limerick, Ireland
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13
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Waller AS. Strangles: taking steps towards eradication. Vet Microbiol 2013; 167:50-60. [PMID: 23642414 DOI: 10.1016/j.vetmic.2013.03.033] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 03/26/2013] [Accepted: 03/29/2013] [Indexed: 10/27/2022]
Abstract
Strangles, caused by the host adapted Lancefield group C bacterium Streptococcus equi sub-species equi (S. equi), is one of the oldest recognised infectious diseases of horses and continues to cause significant welfare and economic cost throughout the world. The ability of S. equi to establish sub-clinical persistent infections primarily in the guttural pouches of convalescent horses has been instrumental to its success. However, the implementation of simple control measures that permit the identification and treatment of persistently infected carriers can prevent further outbreaks of disease at a local level. This review summarises some of the molecular mechanisms exploited by S. equi to cause disease. New qPCR and iELISA diagnostic tests replace culture methodologies as the gold standard for the detection of infected animals. A strategy to maximise the effective application of these tests to direct management methods for the eradication of S. equi infection is presented and the role of preventative vaccines is discussed. In contrast to current understanding, emerging data illustrates the dynamism of the global S. equi population and potential consequences for the effectiveness of currently available vaccines. The ability to use modern vaccines alongside conventional biosecurity and screening procedures will be critical to the large-scale prevention and even eradication of strangles, providing an opportunity to finally break the stranglehold that this disease has on the world's equine industry.
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Affiliation(s)
- Andrew S Waller
- Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU, United Kingdom.
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14
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Diversity of seM in Streptococcus equi subsp. equi isolated from strangles outbreaks. Vet Microbiol 2013; 162:663-669. [DOI: 10.1016/j.vetmic.2012.09.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 09/06/2012] [Accepted: 09/08/2012] [Indexed: 11/22/2022]
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15
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Abstract
Zoonotic infections caused by Streptococcus spp. have been neglected in spite of the fact that frequency and severity of outbreaks increased dramatically in recent years. This may be due to non-identification since respective species are often not considered in human medical diagnostic procedures. On the other hand, an expanding human population concomitant with an increasing demand for food and the increased number of companion animals favour conditions for host species adaptation of animal streptococci. This review aims to give an overview on streptococcal zoonoses with focus on epidemiology and pathogenicity of four major zoonotic species, Streptococcus canis, Streptococcus equi sub. zooepidemicus, Streptococcus iniae and Streptococcus suis.
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16
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Waller AS, Paillot R, Timoney JF. Streptococcus equi: a pathogen restricted to one host. J Med Microbiol 2011; 60:1231-1240. [DOI: 10.1099/jmm.0.028233-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Andrew S. Waller
- Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU, UK
| | - Romain Paillot
- Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU, UK
| | - John F. Timoney
- Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA
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17
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Parkinson NJ, Robin C, Newton JR, Slater J, Waller AS. Molecular epidemiology of strangles outbreaks in the UK during 2010. Vet Rec 2011; 168:666. [PMID: 21672953 DOI: 10.1136/vr.d1485] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The sequence of the Streptococcus equi subspecies equi (S equi) M-like protein (SeM) gene was determined for 105 isolates of S equi from strangles outbreaks in the UK during 2010 and compared with previous data from 2007 to 2008. Twenty-three distinct alleles were identified, including 11 novel alleles. One allele giving rise to a putative truncated M protein was identified from the guttural pouch of an asymptomatic carrier. Allele 9 was the most prevalent, comprising 57.7 per cent of isolates, followed by allele 6 (10.3 per cent). Significant changes in allele prevalence were found between 2007, 2008 and 2010, with an increasing prevalence in SeM-9-related alleles and a corresponding decreasing prevalence in SeM-6-related alleles observed over the period (P<0.001). Geographical proximity of outbreaks caused by some uncommon alleles was apparent between 2007, 2008 and 2010.
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Affiliation(s)
- N J Parkinson
- Centre for Preventive Medicine, Animal Health Trust, Landwades Park, Kentford, Newmarket, Suffolk CB8 7UU
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18
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Ijaz M, Velineni S, Timoney JF. Selective pressure for allelic diversity in SeM of Streptococcus equi does not affect immunoreactive proteins SzPSe or Se18.9. INFECTION GENETICS AND EVOLUTION 2011; 11:1159-63. [PMID: 21256981 DOI: 10.1016/j.meegid.2011.01.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Revised: 12/22/2010] [Accepted: 01/16/2011] [Indexed: 01/25/2023]
Abstract
Streptococcus equi, a clone or biovar of an ancestral Streptococcus zooepidemicus of Lancefield group C causes equine strangles, a highly contagious tonsillitis and lymphadenitis of the head and neck. At least 74 alleles based on N-terminal amino acid sequence of the anti-phagocytic SeM have been observed among isolates of S. equi from N. America, Europe and Japan. A d(N)/d(S) ratio of 5.93 for the 5' region of sem is indicative of positive selective pressure. The aim of this study was to determine whether variations in SeM were accompanied by variations in the surface exposed SzPSe and secreted Se18.9, both of which bind to equine tonsillar epithelium and, along with SeM, elicit strong nasopharyngeal IgA responses during convalescence. Sequences of genes for these proteins from 25 S. equi expressing 19 different SeM alleles isolated over 40 years in different countries were compared. No variation was observed in szpse, except for an Australian isolate with a deletion of a single repeat in the 3' end of the gene. Interestingly, only two SNP loci were detected in se18.9 compared to 93 and 55 in sem and szpse, respectively. The high frequency of nucleotide substitutions in szpse may be related to its mosaic structure since this gene in S. zooepidemicus exists in a variety of combinations of sequence segments and has a central hypervariable region that includes exogenous DNA sequence based on an atypical G-C percentage. In summary, the results of this study document very different responses of streptococcal genes for 3 immunoreactive proteins to selection pressure of the nasopharyngeal mucosal immune response.
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Affiliation(s)
- Muhammad Ijaz
- Maxwell H Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546-0099, United States
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