Understanding equine influenza pathogenesis within the respiratory tract of the horse

Masdefiol Garriga, Andreu (2024) Understanding equine influenza pathogenesis within the respiratory tract of the horse. PhD thesis, University of Glasgow.

Abstract

The pathogenesis of equine influenza in the horse has not been studied in depth. Equine influenza is a relevant, highly contagious viral respiratory disease of the horse that has notable sanitary and economic consequences. As a rarely lethal infection, research has not focused on describing lesions and understanding its pathogenesis, but on developing preventive tools (i.e., vaccines).

I used FFPE respiratory sections of EI-infected horses to describe and study viral spread, histological lesions and expression of specific proteins during the course of the infection, and image analysis software to quantify these lesions and immunostaining in sections from experimentally infected individuals stained with H&E and immunomarkers for viral antigens, innate immunity, apoptosis, mitosis, T and B lymphocytes and type II pneumocytes.

The results obtained showed that EIV spread throughout the entire respiratory tract by 2dpi and the viral nucleoprotein was detectable at least until 14dpi, in high amounts in the lung and intrapulmonary airways, including their surrounding smooth muscle and hyaline cartilage. A transient and fast activation of the innate immunity at 3dpi decelerated its spread for a limited time, although it likely contributed to the development of histological changes too, whereas at late timepoints an increase in T lymphocytes was highlighted, with no apparent direct effect on viral levels. Lesions were evident in the airways at 3dpi and became more severe at 7dpi, showing signs of recovery by 14dpi. On the other hand, infected horses developed pneumonia, likely of bacterial origin, that was identifiable at 7dpi, with extensive areas of oedema, inflammation, haemorrhage and type II pneumocyte proliferation that gained extension and severity at 14dpi.

This study showed that the initial disruption of the respiratory epithelia of the airways caused by EIV impairs the mucociliary system, which leads to the accumulation of mucus and debris that ultimately create the conditions for a secondary bacterial pneumonia to be developed.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Supported by funding from the University of Glasgow Vet Fund, with Dr Pamela Johnston as the recipient, and the Horseracing Betting Levy Board small grants funding scheme.
• Subjects: S Agriculture > SF Animal culture > SF600 Veterinary Medicine
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Supervisor's Name: Murcia, Professor Pablo and Johnston, Dr. Pamela
• Date of Award: 2024
• Depositing User: Theses Team
• Unique ID: glathesis:2024-84732
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 03 Dec 2024 15:03
• Last Modified: 03 Dec 2024 15:07
• Thesis DOI: 10.5525/gla.thesis.84732
• URI: https://theses.gla.ac.uk/id/eprint/84732

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