Date of Award

12-2023

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Program

Biomedical Sciences

Track

Microbiology, Immunology, and Biochemistry

Research Advisor

Stacey Schultz-Cherry, PhD

Committee

Joanne Murphy-Ullrich, PhD; Jason W. Rosch, PhD; Elaine I. Tuomanen, M.D.; Michael A. Whitt, PhD

Keywords

Astrovirus;Autophagy;Cell Cycle;Endoplasmic Reticulum;Infectious Disease;Viral Replication

Abstract

Astrovirus is a non-enveloped positive-sense single-stranded RNA virus that infects the small intestine and causes gastrointestinal disease in most hosts. However, in immunocompromised patients, astrovirus can infect the brain, causing encephalitis and death. Here, we characterize astrovirus induction of replication organelles and dysregulation of cellular processes. It is known that autophagy can play a key role in the viral lifecycle, from entry to egress, and can be either pro-virus or pro-host depending on the virus. RNA viruses often exploit autophagy machinery to create double membrane vesicles (DMVs) as sites of replication and to protect viral RNAs from detection by innate immune sensors. In these studies, we provide the first evidence that astrovirus exploits some, but not all autophagy machinery to assist in viral replication at DMVs. Astrovirus replication and DMV formation relies upon induction of PI3KC3 machinery, but not LC3 conjugation machinery. Astrovirus also disrupts lysosomal enzyme expression. These are the first studies describing astrovirus replication mechanism, and we have shown that the machinery involved may span species infected with astrovirus. We have also shown that astrovirus DMV formation likely originates from the endoplasmic reticulum (ER) and may affect ER stress pathways involved in normal cellular function. These results relate DMV formation to autophagosome biogenesis and suggest that ER stress could play a role in DMV biogenesis. Finally, we have shown that astrovirus replication results in cell cycle arrest during G1 phase of the cell cycle. This is beneficial to the viral life cycle, because G1 phase may provide an environment of growth for the replicating virus. In all, our studies have significantly grown the understanding of astrovirus replication mechanism and disruption of host cellular machinery. This has resulted in relating astrovirus to other positive strand RNA viruses and potentially finding common therapeutics for these viral infections.

Declaration of Authorship

Declaration of Authorship is included in the supplemental files.

ORCID

0000-0002-7330-9872

DOI

10.21007/etd.cghs.2023.0641

Additional Files
2023-023-Bub-DOA.pdf (225 kB)
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