Abstract
The Coronaviridae viral family has been the source of seven zoonotic human coronaviruses, all resulting in substantial economic and health burdens for the global population. The emergence of SARS-CoV-2 and the resulting COVID-19 pandemic caused global disruption, emphasising the urgent need for research investigating the evolution, origin, and immune escape mechanisms of coronaviruses. One protein of particular interest, the spike glycoprotein, plays an important role in all three of these areas. This protein, which gives coronaviruses their characteristic ‘crown’ and name, is heavily involved in determining viral entry into host cells and by extension, their ability to infect novel hosts. Despite the importance of the spike glycoprotein, very little research has been done to investigate the structure of these proteins from animal coronaviruses within the sarbecovirus subgenus. At the commencement of this project, only the spike glycoproteins from three animal coronaviruses, in addition to the SARS and SARS-CoV-2 spike, had been structurally analysed.
This project aimed to address the gap in spike protein structural research via a multi-pronged approach. First, by producing an optimised workflow of protocols to successfully produce high-resolution cryo-electron microscopy structures of spike glycoproteins, from plasmid design through to data processing. Second, to increase the number of spike glycoprotein structures publicly available on the Protein Database, improving the fundamental knowledge surrounding the structure of spike protein. Third, to review the current knowledge surrounding all publicly available spike glycoprotein structures and how they contribute to expanding our understanding of viral evolution, zoonotic origins, and immune escape mechanisms.
These approaches resulted in the publication of multiple scientific articles addressing both the current state of the field and the novel structures produced as a result of this project. Of particular note is that these structures have the highest resolution of all spike glycoproteins published to date.
As a result, this thesis not only contributes fundamental structural knowledge regarding spike glycoproteins from animal coronaviruses with zoonotic potential but also offers the framework for further advancements in the field of structural virology.