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Clinical Progression of Theileria haneyi in Splenectomized Horses Reveals Decreased Virulence Compared to Theileria equi

The global importance of the hemoparasite Theileria haneyi to equine health was recently shown by its resistance to imidocarb dipropionate (ID) and its interference with T. equi clearance by ID in some co-infected horses. Genetic characterization of T. haneyi revealed marked genomic reduction compar...

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Autores principales: Sears, Kelly P., Knowles, Donald P., Fry, Lindsay M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8879895/
https://www.ncbi.nlm.nih.gov/pubmed/35215197
http://dx.doi.org/10.3390/pathogens11020254
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author Sears, Kelly P.
Knowles, Donald P.
Fry, Lindsay M.
author_facet Sears, Kelly P.
Knowles, Donald P.
Fry, Lindsay M.
author_sort Sears, Kelly P.
collection PubMed
description The global importance of the hemoparasite Theileria haneyi to equine health was recently shown by its resistance to imidocarb dipropionate (ID) and its interference with T. equi clearance by ID in some co-infected horses. Genetic characterization of T. haneyi revealed marked genomic reduction compared to T. equi, and initial experiments demonstrated reduced clinical severity in spleen-intact horses. Furthermore, in early experiments, splenectomized horses survived T. haneyi infection and progressed to an asymptomatic carrier state, in stark contrast to the high fatality rate of T. equi in splenectomized horses. Thus, we hypothesized that T. haneyi is less virulent than T. equi. To objectively assess virulence, clinical data from nine splenectomized, T. haneyi-infected horses were evaluated and compared to published data on T. equi-infected, splenectomized horses. Seven of eight splenectomized, T. haneyi-infected horses survived. Further, in six horses co-infected with T. equi and T. haneyi, only horses cleared of T. equi by ID survived splenectomy and became asymptomatic carriers. The reduced virulence of T. haneyi in splenectomized horses instructs why T. haneyi was, until recently, undetected. This naturally occurring comparative reduction in virulence in a natural host provides a foundation for defining virulence mechanisms of theileriosis and Apicomplexa in general.
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spelling pubmed-88798952022-02-26 Clinical Progression of Theileria haneyi in Splenectomized Horses Reveals Decreased Virulence Compared to Theileria equi Sears, Kelly P. Knowles, Donald P. Fry, Lindsay M. Pathogens Article The global importance of the hemoparasite Theileria haneyi to equine health was recently shown by its resistance to imidocarb dipropionate (ID) and its interference with T. equi clearance by ID in some co-infected horses. Genetic characterization of T. haneyi revealed marked genomic reduction compared to T. equi, and initial experiments demonstrated reduced clinical severity in spleen-intact horses. Furthermore, in early experiments, splenectomized horses survived T. haneyi infection and progressed to an asymptomatic carrier state, in stark contrast to the high fatality rate of T. equi in splenectomized horses. Thus, we hypothesized that T. haneyi is less virulent than T. equi. To objectively assess virulence, clinical data from nine splenectomized, T. haneyi-infected horses were evaluated and compared to published data on T. equi-infected, splenectomized horses. Seven of eight splenectomized, T. haneyi-infected horses survived. Further, in six horses co-infected with T. equi and T. haneyi, only horses cleared of T. equi by ID survived splenectomy and became asymptomatic carriers. The reduced virulence of T. haneyi in splenectomized horses instructs why T. haneyi was, until recently, undetected. This naturally occurring comparative reduction in virulence in a natural host provides a foundation for defining virulence mechanisms of theileriosis and Apicomplexa in general. MDPI 2022-02-16 /pmc/articles/PMC8879895/ /pubmed/35215197 http://dx.doi.org/10.3390/pathogens11020254 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Sears, Kelly P.
Knowles, Donald P.
Fry, Lindsay M.
Clinical Progression of Theileria haneyi in Splenectomized Horses Reveals Decreased Virulence Compared to Theileria equi
title Clinical Progression of Theileria haneyi in Splenectomized Horses Reveals Decreased Virulence Compared to Theileria equi
title_full Clinical Progression of Theileria haneyi in Splenectomized Horses Reveals Decreased Virulence Compared to Theileria equi
title_fullStr Clinical Progression of Theileria haneyi in Splenectomized Horses Reveals Decreased Virulence Compared to Theileria equi
title_full_unstemmed Clinical Progression of Theileria haneyi in Splenectomized Horses Reveals Decreased Virulence Compared to Theileria equi
title_short Clinical Progression of Theileria haneyi in Splenectomized Horses Reveals Decreased Virulence Compared to Theileria equi
title_sort clinical progression of theileria haneyi in splenectomized horses reveals decreased virulence compared to theileria equi
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8879895/
https://www.ncbi.nlm.nih.gov/pubmed/35215197
http://dx.doi.org/10.3390/pathogens11020254
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