Investigating equine host barriers to infection with influenza A viruses

Crispell, Joanna Lorna (2018) Investigating equine host barriers to infection with influenza A viruses. PhD thesis, University of Glasgow.

Abstract

Influenza A viruses (IAVs) are significant pathogens of humans and animals whose main natural host is considered to be wild waterfowl. IAVs have jumped the species barrier on multiple occasions, sometimes with devastating consequences. Successful infection and onward transmission (i.e. viral emergence) requires highly specific interactions between virus and host proteins. However, how an avian virus adapts to a mammalian host to establish as a novel pathogen after initial interspecies transmission is not yet clear.

It was hypothesized that adaptation of an avian virus to mammals would involve changes in virus-host interactions that would result in more efficient viral replication and counteraction of immune responses. To test this hypothesis this thesis firstly describes the characterization of an equine dermal cell line (E.Derm) for the study of infection with EIVs. A panel of H3N8 AIVs was selected to investigate how equine host barriers affect the replication kinetics of distinct viruses. Finally, the transcriptome of the equine cells was investigated after infection with two evolutionary distinct H3N8 equine influenza viruses (H3N8 EIVs), and treatment with interferon-alpha (IFN-α). H3N8 EIV is an avian-origin virus that emerged in 1960s and has been circulating in horses for over 50 years, thus providing a natural model system to study the interspecies transmission and post-transfer adaptation of an avian influenza virus to a mammalian host.

To examine the cellular response to infection, equine dermal cells (E.Derm) were infected with either A/equine/Uruguay/63 or A/equine/Ohio/2003. Total RNA was extracted at 4 and 24 hours post-infection for RNA sequencing and downstream transcriptomics analysis. Mock-infected cells and interferon-treated cells were also included for comparison purposes. RNA-seq data were analysed using CuffDiff2 to identify differentially expressed (DE) genes between samples. Ingenuity Pathway Analysis was used to determine the intracellular pathways in which DE genes were involved. The results showed clear differences on the intracellular pathways affected between the viruses, which were especially evident during the eclipse phase of virus replication. Distinct intracellular pathways were identified as important for EIV adaptation to the horse, which in turn could be employed by other avian influenza viruses to establish in mammals.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: influenza, equine, evolution, RNASeq, transcriptomics, virus.
• Subjects: Q Science > QR Microbiology > QR355 Virology
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Infection & Immunity > Centre for Virus Research
• Supervisor's Name: Murcia, Dr. Pablo and Bhella, Dr. David
• Date of Award: 2018
• Depositing User: Dr Joanna Crispell
• Unique ID: glathesis:2018-30622
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 06 Jun 2018 12:18
• Last Modified: 01 Aug 2022 08:42
• URI: https://theses.gla.ac.uk/id/eprint/30622

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