Currently, human norovirus is the leading cause of acute gastroenteritis and accounts for
most cases of foodborne illnesses in the United States each year. Due to its tissue culture
inefficiency, studies of human norovirus have been crippled for more than forty years.Tulane virus
(TV) stands out as a suitable surrogate of human norovirus given its high amino acid identity with
human norovirus and its well-established cell culture system. It was first isolated from rhesus
macaques (Macaca mulatta) in 2008 and identified as a novel Calicivirusrepresenting a new genus,
Recovirus genus (Farkas et al., 2008). However, there are still unanswered questions about its
infectious cycle and the essential factors for its infection.
In this study, we have obtained a TV variant (the 9-6-17 strain) that has lost the binding
ability to the B-type histo-blood group antigen (HBGA), which was proposed to be the receptor of
both TV and human norovirus. In the first chapter, we outline how the sequence analysis,structural
biology studies, and mutagenesis studies of the 9-6-17 TV strain have shed light on the interaction
with its host cell receptor. To investigate the key residues for HBGA binding, we established the
full-length infectious clone of the 9-6-17 TV strain. We present a highly selective transformation
of serine 367, located in the predicted HBGA binding site, into a lysine residu e. Our results
advance the understanding of genetic changes in TV required for adaptation to cell culture
environments.
Cryo-EM is an awarding winning technique that has been the greatest scientific breakthrough
in recent years. It was awarded the Nobel Prize in Chemistry in 2017. Despite the technological
advances of the direct electron detector and image processing software, several major roadblocks
remain for high-resolution structure determination with cryo-EM. In the later chapters, we
explored the most efficient way of using VPP to enhance image contrast, how to tackle the airwater interface problem by encapsulating target protein, how to reach a higher resolution by
refining high order parameters, and the helical indexing problem in real space. These technical
advances would benefit the whole cryo-EM community by providing convenient tools or insights
for future directions.
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/17096810 |
| Date | 30 November 2021 |
| Creators | Chen Sun (11768708) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY-ND 4.0 |
| Relation | https://figshare.com/articles/thesis/Structural_Study_of_Tulane_Virus_and_Its_Host_Cell_Factors_and_Applications_in_Cryo-EM/17096810 |
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