Identifying biophysical determinants of virus-cell fusion through live-cell imaging

Thesis

The biophysical properties of both enveloped virus and cell membranes must be favourable for successful fusion and entry of the virus into its host. Characterising these properties in cells and virions is critical for understanding and manipulating target cell susceptibility to infection, as well as blocking infection by cell-autonomous antiviral proteins. To characterise such properties, we developed imaging assays multiplexing genetically-encoded biosensors concomitant with single virus tracking in live cells to uncover a link between the host cell membrane biophysical landscape, host metabolic state, and virus fusion. Expanding the utility of these assays, we characterised a conserved GxxxG oligomerisation motif in antiviral protein interferon-inducible transmembrane 3 (IFITM3), linking the oligomeric state of IFITM3 and its antiviral activity to its ability to rigidify host cell membranes. Interestingly, the GxxxG motif is not intact in human IFITM5, and this IFITM protein is traditionally not associated with antiviral immunity. Therefore, we restored the GxxxG motif in IFITM5 to determine if its oligomerisation capacity and antiviral activity was potentiated. Collectively, the results described in this dissertation connects the fusion of viruses with the biophysical properties of membranes of the host cell, which are dependent on host metabolic state and the ability of IFITM proteins to oligomerise and rigidify membranes.

Authors: Coomer, CA

• DOI: 10.5287/ora-aenoovaj2
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: Virus fusion; IFITM; Restriction factors
• Subjects: Microscopy; Virology