Streptococcus equi subsp. zooepidemicus Supernatant Containing Streptolysin S Alters the Equine Nasal and Vaginal Mucosa, Modulating Equine Herpesvirus 1, 3 and 4 Infections.
Abstract: The equine respiratory and reproductive tract microbiomes are complex and subject to constant fluctuations. Among the microbial inhabitants, subsp. (SEZ) is recognized as the dominant bacterium. It is an opportunistic pathogen that may occasionally lead to various types of infections. A key virulence factor of SEZ is the streptolysin S (SLS) toxin, which is responsible for the characteristic β-hemolysis on blood agar and tissue damage. Viruses and bacteria may interact and aggravate lesions and disease. This study aimed to evaluate the impact of an SLS-containing supernatant from SEZ on the nasal and vaginal mucosa and the subsequent replication of equine herpesviruses. The SLS-containing supernatant was prepared, and three 10-fold dilutions (optical density "OD" 10, 10, 10) were applied to equine nasal and vaginal explants. Untreated and EGTA-treated explants served as controls. Epithelial integrity was assessed by measuring the thickness and intercellular spaces. Nasal explants were inoculated with EHV-1 and EHV-4, while vaginal explants received EHV-1 and EHV-3. Viral replication was estimated via immunofluorescence staining and confocal microscopy. SLS-containing supernatants 10 and 10 compromised epithelial integrity. Viral replication increased in explants treated with SLS 10, demonstrating SLS's damaging effects on the epithelium, facilitating equine herpesvirus replication.
Publication Date: 2025-07-14 PubMed ID: 40733597PubMed Central: PMC12299918DOI: 10.3390/v17070980Google Scholar: Lookup
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Summary
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This research evaluates how a toxin created by a common bacteria in horses’ respiratory and reproductive tracts influences infection rates of several types of equine herpesviruses. They found that this toxin compromises the physical integrity of these tracts, which can enable higher rates of viral replication.
Research Background
- The tracts where an animal breathes and reproduces are home to multiple types of microbes. In horses, one particular bacteria known as Streptococcus equi subsp. zooepidemicus (SEZ) frequently predominates.
- While this bacterium can coexist with the horse without issues, it can occasionally cause infections. A toxin named streptolysin S (SLS) that this bacterium produces can damage tissue and cause a specific type of damage to red blood cells, known as β-hemolysis.
- The researchers note that bacteria and viruses can sometimes interact to worsen tissue damage and disease. This particular study was designed to evaluate how the SLS toxin might impact herpesviruses’ ability to infect the nasal and vaginal mucosa of horses.
Methodology
- The research team prepared a concoction inclusive of the SLS toxin. Several dilutions of this mixture were applied to tissue samples from horse nasal and vaginal linings respectively.
- Tissue samples that weren’t treated with the toxin, and samples that received a chemical treatment to cancel out the toxin’s action were used as controls.
- The researchers evaluated the tissue’s integrity by assessing its thickness and intercellular spaces.
- These tissue samples were then exposed to three types of equine herpesviruses for potentially initiating infections. The replication of these viruses was then estimated using a staining technique that helps visualize proteins and a microscopy technique that allows 3D visualization of the samples.
Findings
- Two specific dilutions of the SLS-containing concoction were found to compromise the integrity of the tissue samples.
- An increase in viral replication was observed specifically in the tissue samples that were treated with the highest concentration of the SLS toxin. This finding indicates the potential for this toxin to increase susceptibility to herpesvirus infection by damaging the protective lining of the horse’s nasal and vaginal tracts.
Cite This Article
APA
Mohamed E, Van Cleemput J, Şahin B, Van den Broeck W, Boyen F, Nauwynck H.
(2025).
Streptococcus equi subsp. zooepidemicus Supernatant Containing Streptolysin S Alters the Equine Nasal and Vaginal Mucosa, Modulating Equine Herpesvirus 1, 3 and 4 Infections.
Viruses, 17(7), 980.
https://doi.org/10.3390/v17070980 Publication
Researcher Affiliations
- Department of Translational Physiology, Infectiology and Public Health, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium.
- Department of Animal Medicine, Faculty of Veterinary Medicine, Benha University, Moshtohor 13736, Egypt.
- Department of Translational Physiology, Infectiology and Public Health, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium.
- Department of Virology, Institute of Health Sciences, Burdur Mehmet Akif Ersoy University, 15100 Burdur, Turkey.
- Department of Morphology, Medical Imaging, Orthopedics and Nutrition, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium.
- Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium.
- Department of Translational Physiology, Infectiology and Public Health, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium.
MeSH Terms
- Animals
- Horses
- Female
- Vagina / virology
- Vagina / microbiology
- Herpesviridae Infections / veterinary
- Herpesviridae Infections / virology
- Herpesvirus 1, Equid / physiology
- Herpesvirus 1, Equid / drug effects
- Streptolysins / pharmacology
- Streptolysins / metabolism
- Horse Diseases / virology
- Horse Diseases / microbiology
- Virus Replication / drug effects
- Nasal Mucosa / virology
- Nasal Mucosa / drug effects
- Nasal Mucosa / microbiology
- Mucous Membrane / virology
- Mucous Membrane / drug effects
- Bacterial Proteins / pharmacology
- Bacterial Proteins / metabolism
- Herpesvirus 4, Equid / physiology
- Herpesvirus 4, Equid / drug effects
- Streptococcus
- Streptococcus equi
- Varicellovirus / physiology
- Varicellovirus / drug effects
Grant Funding
- 2021060310 / Egyptian Ministry of Higher Education and Scientific Research
- GOA013-17 / Ghent University
- G035920N / Research Foundation - Flanders
Conflict of Interest Statement
The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of the data; in the writing of the manuscript; or in the decision to publish the results.
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