<i>Streptococcus equi</i> subsp. <i>zooepidemicus</i> Supernatant Containing Streptolysin S Alters the Equine Nasal and Vaginal Mucosa, Modulating Equine Herpesvirus 1, 3 and 4 Infections

The equine respiratory and reproductive tract microbiomes are complex and subject to constant fluctuations. Among the microbial inhabitants, <i>Streptococcus equi</i> subsp. <i>zooepidemicus</i> (SEZ) is recognized as the dominant bacterium. It is an opportunistic pathogen th...

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Main Authors: Eslam Mohamed, Jolien Van Cleemput, Burak Şahin, Wim Van den Broeck, Filip Boyen, Hans Nauwynck
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Viruses
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Online Access:https://www.mdpi.com/1999-4915/17/7/980
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author Eslam Mohamed
Jolien Van Cleemput
Burak Şahin
Wim Van den Broeck
Filip Boyen
Hans Nauwynck
author_facet Eslam Mohamed
Jolien Van Cleemput
Burak Şahin
Wim Van den Broeck
Filip Boyen
Hans Nauwynck
author_sort Eslam Mohamed
collection DOAJ
description The equine respiratory and reproductive tract microbiomes are complex and subject to constant fluctuations. Among the microbial inhabitants, <i>Streptococcus equi</i> subsp. <i>zooepidemicus</i> (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<sup>−2</sup>, 10<sup>−3</sup>, 10<sup>−4</sup>) 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<sup>−2</sup> and 10<sup>−3</sup> compromised epithelial integrity. Viral replication increased in explants treated with SLS 10<sup>−3</sup>, demonstrating SLS’s damaging effects on the epithelium, facilitating equine herpesvirus replication.
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spelling doaj-art-eacd99cc4f3a42ca92be19e31b6bcd722025-08-20T02:47:08ZengMDPI AGViruses1999-49152025-07-0117798010.3390/v17070980<i>Streptococcus equi</i> subsp. <i>zooepidemicus</i> Supernatant Containing Streptolysin S Alters the Equine Nasal and Vaginal Mucosa, Modulating Equine Herpesvirus 1, 3 and 4 InfectionsEslam Mohamed0Jolien Van Cleemput1Burak Şahin2Wim Van den Broeck3Filip Boyen4Hans Nauwynck5Department of Translational Physiology, Infectiology and Public Health, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, BelgiumDepartment of Translational Physiology, Infectiology and Public Health, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, BelgiumDepartment of Virology, Institute of Health Sciences, Burdur Mehmet Akif Ersoy University, 15100 Burdur, TurkeyDepartment of Morphology, Medical Imaging, Orthopedics and Nutrition, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, BelgiumDepartment of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, BelgiumDepartment of Translational Physiology, Infectiology and Public Health, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, BelgiumThe equine respiratory and reproductive tract microbiomes are complex and subject to constant fluctuations. Among the microbial inhabitants, <i>Streptococcus equi</i> subsp. <i>zooepidemicus</i> (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<sup>−2</sup>, 10<sup>−3</sup>, 10<sup>−4</sup>) 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<sup>−2</sup> and 10<sup>−3</sup> compromised epithelial integrity. Viral replication increased in explants treated with SLS 10<sup>−3</sup>, demonstrating SLS’s damaging effects on the epithelium, facilitating equine herpesvirus replication.https://www.mdpi.com/1999-4915/17/7/980SEZSLS toxinEHV-1EHV-3EHV-4horse mucosal microbiome
spellingShingle Eslam Mohamed
Jolien Van Cleemput
Burak Şahin
Wim Van den Broeck
Filip Boyen
Hans Nauwynck
<i>Streptococcus equi</i> subsp. <i>zooepidemicus</i> Supernatant Containing Streptolysin S Alters the Equine Nasal and Vaginal Mucosa, Modulating Equine Herpesvirus 1, 3 and 4 Infections
Viruses
SEZ
SLS toxin
EHV-1
EHV-3
EHV-4
horse mucosal microbiome
title <i>Streptococcus equi</i> subsp. <i>zooepidemicus</i> Supernatant Containing Streptolysin S Alters the Equine Nasal and Vaginal Mucosa, Modulating Equine Herpesvirus 1, 3 and 4 Infections
title_full <i>Streptococcus equi</i> subsp. <i>zooepidemicus</i> Supernatant Containing Streptolysin S Alters the Equine Nasal and Vaginal Mucosa, Modulating Equine Herpesvirus 1, 3 and 4 Infections
title_fullStr <i>Streptococcus equi</i> subsp. <i>zooepidemicus</i> Supernatant Containing Streptolysin S Alters the Equine Nasal and Vaginal Mucosa, Modulating Equine Herpesvirus 1, 3 and 4 Infections
title_full_unstemmed <i>Streptococcus equi</i> subsp. <i>zooepidemicus</i> Supernatant Containing Streptolysin S Alters the Equine Nasal and Vaginal Mucosa, Modulating Equine Herpesvirus 1, 3 and 4 Infections
title_short <i>Streptococcus equi</i> subsp. <i>zooepidemicus</i> Supernatant Containing Streptolysin S Alters the Equine Nasal and Vaginal Mucosa, Modulating Equine Herpesvirus 1, 3 and 4 Infections
title_sort i streptococcus equi i subsp i zooepidemicus i supernatant containing streptolysin s alters the equine nasal and vaginal mucosa modulating equine herpesvirus 1 3 and 4 infections
topic SEZ
SLS toxin
EHV-1
EHV-3
EHV-4
horse mucosal microbiome
url https://www.mdpi.com/1999-4915/17/7/980
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