Streptococcus equi with truncated M-proteins isolated from outwardly healthy horses.
Abstract: The M-protein genes of Streptococcus equi isolated from 17 outwardly healthy horses after 4 strangles outbreaks had ended, including a quarantined animal, were compared with those of S. equi isolates from 167 active cases of strangles across 4 countries. The healthy horses included 16 persistent S. equi carriers, at least one from each of the four outbreaks. These carriers, despite being outwardly healthy, had empyema of the guttural pouch(es), an enlargement of the equine Eustachian tube. A persistent carrier from two of these outbreaks, the quarantined animal and a healthy animal with normal guttural pouches, from which S. equi was isolated only once, were colonized by variant S. equi with truncated M-protein genes (24% of outwardly healthy animals with S. equi). The truncated M-protein genes had in-frame deletions in slightly different positions between the signal sequence and the central repeat region, equivalent to approximately 20% of the mature expressed protein. Immunoblotting with antibody to recombinant M-protein confirmed that the variants expressed a truncated form of the M-protein. In contrast to the outwardly healthy S. equi carriers, only 1/167 of S. equi isolates from strangles cases possessed a truncated M-protein gene (<1%; Fisher's exact test, P=0.0002). Compared with isolates from healthy horses with a truncated M-protein, much more of the N terminus of the truncated M-protein was retained in the variant S. equi from a strangles case. Variant S. equi from outwardly healthy animals were more susceptible to phagocytosis by neutrophils in vitro than typical isolates. This is the first report of detection of S. equi with a truncated M-protein. The distribution of the variants between strangles cases and carriers suggests that the 80% of the M-protein retained in the variants may contribute to colonization whilst the deleted portion of the gene may be needed for full virulence.
Publication Date: 2000-06-10 PubMed ID: 10846214DOI: 10.1099/00221287-146-6-1361Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The study focuses on the variant Streptococcus equi bacteria with truncated M-protein genes observed in outwardly healthy horses. The researchers suggest that while a significant portion of the M-protein might contribute to the bacterium’s colonization, the deleted parts may be necessary for its full virulence.
Scope of the Study
- The research involved the examination of Streptococcus equi isolated from 17 healthy horses after the conclusion of four strangles outbreaks.
- These horses, despite appearing healthy, exhibited empyema of the guttural pouches, a condition characterized by an enlarged Eustachian tube.
- The comparative aspect of the study included Streptococcus equi isolates from 167 active strangles cases across four countries.
Findings about the M-Protein
- The researchers have focused their attention on M-proteins as these are essential for the bacterium’s virulence (ability to cause disease).
- The horses appearing healthy were found to harbor variant Streptococcus equi, characterized by truncated M-protein genes, i.e., these genes had in-frame deletions in different positions between their signal sequence and the central repeat region.
- These variants constituted approximately 24% of the total, and the immune response against these confirmed that these variants express a shortened form of the M-protein.
Variations of M-Protein in Healthy Carriers and Strangles Cases
- In contrast to outwardly healthy horses, only 1 out of 167 of isolates from strangles cases possessed a truncated M-protein gene, indicating that the condition is much less common in diseased individuals.
- Moreover, the strangles-related variant retained a larger part of the N terminus of the truncated M-protein compared to the healthy horse isolate.
Implications for Disease Susceptibility
- In laboratory conditions, it was found that variant Streptococcus equi isolated from outwardly healthy animals were more susceptible to phagocytosis (a process that destroys pathogens) by neutrophils, compared to typical isolates.
- The results suggest that the retained 80% of the M-protein may assist in the bacterium’s colonization, while the deleted parts could be crucial for full virulence.
- This is the first report detecting Streptococcus equi with truncated M-protein, hence, it yields a significant contribution to the understanding of bacterial behavior and potential disease prevention in horses.
Cite This Article
APA
Chanter N, Talbot NC, Newton JR, Hewson D, Verheyen K.
(2000).
Streptococcus equi with truncated M-proteins isolated from outwardly healthy horses.
Microbiology (Reading), 146 ( Pt 6), 1361-1369.
https://doi.org/10.1099/00221287-146-6-1361 Publication
Researcher Affiliations
- Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU, UK1.
- Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU, UK1.
- Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU, UK1.
- Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU, UK1.
- Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU, UK1.
MeSH Terms
- Amino Acid Sequence
- Animals
- Antibodies, Bacterial
- Antigens, Bacterial
- Bacterial Outer Membrane Proteins
- Bacterial Proteins / genetics
- Bacterial Proteins / immunology
- Base Sequence
- Carrier Proteins / genetics
- Carrier Proteins / immunology
- Carrier State / immunology
- Carrier State / microbiology
- DNA Primers / genetics
- DNA, Bacterial / genetics
- Genes, Bacterial
- Genetic Variation
- Horse Diseases / immunology
- Horse Diseases / microbiology
- Horses / microbiology
- In Vitro Techniques
- Molecular Sequence Data
- Neutrophils / immunology
- Phagocytosis
- Polymerase Chain Reaction
- Recombinant Proteins / genetics
- Recombinant Proteins / immunology
- Sequence Deletion
- Sequence Homology, Amino Acid
- Streptococcal Infections / immunology
- Streptococcal Infections / microbiology
- Streptococcal Infections / veterinary
- Streptococcus equi / genetics
- Streptococcus equi / isolation & purification
- Streptococcus equi / pathogenicity
- Virulence / genetics
Citations
This article has been cited 10 times.- Wan J, Weldon E, Ganser G, Morris ERA, Hughes EV, Bordin AI, Heine PA, Hust M, Cohen ND, Gill JJ, Liu M. Immunogenic Streptococcus equi cell surface proteins identified by ORFeome phage display. mSphere 2025 Dec 23;10(12):e0062625.
- Rotinsulu DA, Ewers C, Kerner K, Amrozi A, Soejoedono RD, Semmler T, Bauerfeind R. Molecular Features and Antimicrobial Susceptibilities of Streptococcus equi ssp. equi Isolates from Strangles Cases in Indonesia. Vet Sci 2023 Jan 10;10(1).
- 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 Jan;55(1):92-101.
- Morris ERA, Boyle AG, Riihimäki M, Aspán A, Anis E, Hillhouse AE, Ivanov I, Bordin AI, Pringle J, Cohen ND. Differences in the genome, methylome, and transcriptome do not differentiate isolates of Streptococcus equi subsp. equi from horses with acute clinical signs from isolates of inapparent carriers. PLoS One 2021;16(6):e0252804.
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- Höner OP, Wachter B, Goller KV, Hofer H, Runyoro V, Thierer D, Fyumagwa RD, Müller T, East ML. The impact of a pathogenic bacterium on a social carnivore population. J Anim Ecol 2012 Jan;81(1):36-46.
- Kelly C, Bugg M, Robinson C, Mitchell Z, Davis-Poynter N, Newton JR, Jolley KA, Maiden MC, Waller AS. Sequence variation of the SeM gene of Streptococcus equi allows discrimination of the source of strangles outbreaks. J Clin Microbiol 2006 Feb;44(2):480-6.
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