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In vivo pathogenicity and resistance to phagocytosis of Streptococcus equi strains with different levels of capsule expression.
Abstract: The glossy non-encapsulated strain of Steptococcus equi, NCTC 9682, was compared with the matt strain Hidaka/95/2 which expresses a medium sized capsule and with the mucoid CF32 which expresses a large sized capsule in phagocytosis assays and for virulence in inoculated horses. The three strains, NCTC 9682, Hidaka /95/2 and CF32 produced 2.0, 3.1, and 5.3 mg/g wet cells respectively after 3 h incubation, but similar amounts of M-like proteins, cytotoxin and mitogen. NCTC 9682 showed no resistance to phagocytosis by equine neutrophils regardless of the presence of opsonin while strains Hidaka /95/2 and CF32 showed almost complete resistance to phagocytosis. Furthermore, NCTC 9682 produced no clinical disease although it infected the guttural pouch and caused seroconversion. Typical strangles with guttural pouch invasion was observed in all horses infected with encapsulated strains.
Publication Date: 1999-08-31 PubMed ID: 10466503DOI: 10.1016/s0378-1135(99)00051-6Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Comparative Study
- Journal Article
Summary
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This study compares the pathogenicity and resistance to phagocytosis of different strains of Streptococcus equi—NCTC 9682 (non-encapsulated), Hidaka /95/2 (medium capsule), and CF32 (large capsule)—and reveals how capsule size affects disease progression in horses.
Introduction
- The research revolves around understanding the pathogenicity—that is, the capacity to cause disease—of different strains of bacteria Streptococcus equi, which is primarily responsible for a condition known as strangles in horses.
- The strains under investigation were categorized according to their capsule sizes: non-encapsulated, medium, and large capsule. The capsule on a bacterium can offer protection from the immune system and is a major factor in bacterial virulence.
Methodology and Results
- The researchers compared these strains in terms of their resistance to phagocytosis, a process by which cells of the immune system (like neutrophils) engulf and destroy bacteria.
- They discovered that the non-encapsulated strain NCTC 9682 had no resistance to phagocytosis regardless of the presence of opsonin (a substance that enhances phagocytosis), while the encapsulated strains (Hidaka /95/2 and CF32) showed nearly complete resistance.
- All three strains produced similar amounts of M-like proteins, cytotoxin, and mitogen after three hours of incubation, but with different yields of bacteria at 2.0, 3.1, and 5.3 mg/g wet cells for NCTC 9682, Hidaka /95/2, and CF32, respectively.
Clinical Observations
- From a clinical viewpoint, it was seen that while NCTC 9682 infected the guttural pouch (an air sac in the equine respiratory tract) and led to seroconversion (the period during which antibodies develop and become detectable), it did not produce clinical disease.
- On the contrary, the encapsulated strains (Hidaka /95/2 and CF32) caused typical strangles with guttural pouch invasion in all infected horses. This indicates that the encapsulated strains were more virulent.
Conclusion
- Ultimately, this research indicates that the presence and size of the capsule in Streptococcus equi strains can significantly influence their resistance to phagocytosis and their potential to cause disease.
- This finding may contribute to the development of more effective strategies in treating and preventing strangles in horses.
Cite This Article
APA
Anzai T, Timoney JF, Kuwamoto Y, Fujita Y, Wada R, Inoue T.
(1999).
In vivo pathogenicity and resistance to phagocytosis of Streptococcus equi strains with different levels of capsule expression.
Vet Microbiol, 67(4), 277-286.
https://doi.org/10.1016/s0378-1135(99)00051-6 Publication
Researcher Affiliations
- Epizootic Research Station, Equine Research Institute, Japan Racing Association, Tochigi. anzai@epizoo.equinst.go.jp
MeSH Terms
- Animals
- Antibodies, Bacterial / blood
- Bacterial Capsules / genetics
- Blotting, Western / veterinary
- Carbazoles / chemistry
- Carbon
- Colony Count, Microbial / veterinary
- Coloring Agents / chemistry
- Enzyme-Linked Immunosorbent Assay / veterinary
- Female
- Formazans / chemistry
- Gene Expression Regulation, Bacterial
- Horse Diseases / microbiology
- Horses
- Hyaluronic Acid / analysis
- Hyaluronic Acid / genetics
- Japan
- Lymph Nodes / microbiology
- Palatine Tonsil / microbiology
- Phagocytosis / genetics
- Streptococcal Infections / microbiology
- Streptococcal Infections / veterinary
- Streptococcus equi / genetics
- Streptococcus equi / immunology
- Streptococcus equi / pathogenicity
- Tetrazolium Salts / chemistry
- United States
Citations
This article has been cited 12 times.- Gao W, Zhang X, Zhang G, Zuo M, Cao W, Xie Z, Liu H. Is hyaluronic acid production transcriptionally regulated? A transcriptional repressor gene deletion study in Streptococcus zooepidemicus. Appl Microbiol Biotechnol 2021 Nov;105(21-22):8495-8504.
- Kasuya K, Tanaka N, Oshima F, Fujisawa N, Saito M, Tagami K, Niwa H, Sasai K. Genetic analysis of Streptococcus equi subsp. equi isolated from horses imported into Japan. J Vet Med Sci 2019 Jun 28;81(6):924-927.
- Timoney JF, Suther P, Velineni S, Artiushin SC. The Antiphagocytic Activity of SeM of Streptococcus equi Requires Capsule. J Equine Sci 2014;25(2):53-6.
- Cress BF, Englaender JA, He W, Kasper D, Linhardt RJ, Koffas MA. Masquerading microbial pathogens: capsular polysaccharides mimic host-tissue molecules. FEMS Microbiol Rev 2014 Jul;38(4):660-97.
- Marcellin E, Gruber CW, Archer C, Craik DJ, Nielsen LK. Proteome analysis of the hyaluronic acid-producing bacterium, Streptococcus zooepidemicus. Proteome Sci 2009 Mar 28;7:13.
- Liu M, McClure MJ, Zhu H, Xie G, Lei B. The Two-Component Regulatory System VicRK is Important to Virulence of Streptococcus equi Subspecies equi. Open Microbiol J 2008;2:89-93.
- Locke JB, Colvin KM, Datta AK, Patel SK, Naidu NN, Neely MN, Nizet V, Buchanan JT. Streptococcus iniae capsule impairs phagocytic clearance and contributes to virulence in fish. J Bacteriol 2007 Feb;189(4):1279-87.
- Lannergård J, Flock M, Johansson S, Flock JI, Guss B. Studies of fibronectin-binding proteins of Streptococcus equi. Infect Immun 2005 Nov;73(11):7243-51.
- Buchanan JT, Stannard JA, Lauth X, Ostland VE, Powell HC, Westerman ME, Nizet V. Streptococcus iniae phosphoglucomutase is a virulence factor and a target for vaccine development. Infect Immun 2005 Oct;73(10):6935-44.
- He L, Khine NO, Song J, Loubière C, Butaye P. Geographic diversity of the Streptococcus equi subsp. equi accessory genome: implications for vaccines and global surveillance. Front Vet Sci 2025;12:1721958.
- Seeger MG, de Vargas APC, Vogel FSF, Cargnelutti JF. Streptococcus equi subsp. equi isolated from horses in Southern Brazil: molecular and phenotypic analyses. Braz J Microbiol 2025 Dec;56(4):2987-2996.
- Abdul-Latif SAK, Yousif AA. Molecular study of Streptococcus equi isolated from horses with strangles in Iraq. Open Vet J 2025 Feb;15(2):731-737.
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