Investigating the role of RNA modifying enzymes in RNA virus infection

Jarmson, Innes Gordon (2025) Investigating the role of RNA modifying enzymes in RNA virus infection. PhD thesis, University of Glasgow.

Abstract

Viruses, as obligate intracellular parasites, rely heavily on their close interactions with host cells to replicate. To have a successful lifecycle, a virus must subvert the host machinery for its own use, while avoiding inducing an immune response in the cell. One mechanism of inducing an immune response is the sensing of foreign nucleic acid, whether that be through unusual nucleic acid structure or specific motifs on viral RNA and DNA. In the resting cell, all post transcriptional modifications of cellular RNA play an important role in the life cycle of RNA, and these modifications in turn act as a signal in the cell to avoid triggering an immune response. In the eternal battle of viruses and their hosts to adapt and counter adapt to overcome each other, viruses have evolved intricate mechanisms to avoid mounting an immune response. One such method is to mimic the cellular landscape of RNA to avoid being sensed by the host. To do this, viruses hijack cellular RNA modifying enzymes to ‘decorate’ their genomes. These modifications also serve a functional purpose in viral RNA and can enhance processes like translation of viral mRNAs. However, in the co-evolution of virus and host trying to counter each other, the host cell can also methylate viral RNA to initiate an innate immune mechanism to restrict viral growth. To understand the dynamicity of RNA modifications in viral infection, I have created a CRISPR-Cas9 knockout platform where I systematically knockout each known human RNA modifying enzyme and observe if the lack of the gene increases or decreases viral infection. This allows us to determine whether the gene of interest inhibits or enhances viral infection. Those genes that are identified as necessary for viral infection are subjected to further analysis to identify the function of these RNA modifications and if the same modifications are shared between viruses. Using this platform, I identified several RNA modifying enzymes and characterised one protein that had an antiviral effect against several viruses – NOP2. In the resting cell NOP2 is involved in ribosome biogenesis and I established that after infection it switches its activity to become an antiviral effector. The data in this thesis demonstrates the utility of arrayed CRISPR/Cas9 screening to identify new proteins involved in virus infection and how it can be used as a discovery-based platform to further characterise the host-virus arms race.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• 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: Castello, Professor Alfredo and Wilson, Professor Sam
• Date of Award: 2025
• Depositing User: Theses Team
• Unique ID: glathesis:2025-84872
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 07 Feb 2025 11:56
• Last Modified: 07 Feb 2025 12:01
• Thesis DOI: 10.5525/gla.thesis.84872
• URI: https://theses.gla.ac.uk/id/eprint/84872

Related URLs

• Data DOI