Publication Date

2023

Document Type

Thesis

Committee Members

Abimbola O. Kolawole, Ph.D. (Advisor); Paula Ann Bubulya, Ph.D. (Committee Member); Shulin Ju, Ph.D. (Committee Member)

Degree Name

Master of Science (MS)

Abstract

During infection, viruses are released from infected cells and spread to neighboring cells either through a lytic pathway (by rupturing cells), a non-lytic pathway (such as the use of extracellular vesicles), or both pathways. Human astroviruses (HAstV) are highly prevalent non-enveloped positive sense RNA viruses. They are separated into three clades, classic-type, MLB-type and VA-type, in humans. They are identified as the third leading cause of viral gastroenteritis in children, the elderly, and immunocompromised patients. Yet, little is known about the replication, transmission, immunity, and epidemiology of these viruses. Thus, I sought to investigate the possible pathways HAstV utilize to exit infected cells. First, I investigated the role of cell lysis in HAstV release. To do this, I measured cell death in HAstV infected Caco2 and Huh7.5 cells WST-1 assay for cell proliferation, and Annexin V/propidium iodide staining for cell apoptosis using microscopy and flow cytometry. Interestingly, HAstV-1, MLB-2 and VA-1 did not show significant cytopathic effect in infected cells despite the several log increases in viral titer as determined by RT-qPCR. Second, we investigated the role of extracellular vesicles (EV) in HAstV release. Using pharmaceuticals to modulate EV synthesis, we found that HAstV release increased when Forskolin and Norepinephrine were used to enhance EV production in infected Caco2 and Huh7.5 cells. Conversely, inhibition of EV production by GW4869 significantly reduced HAstV release in infected cells. Additionally, EV isolated from infected cells support new infection without trypsin activation. Our data showed an association between EV produced by host cells and the released HAstV particles. This suggests that human astrovirus egress is non-lytic and may involve the use of EV

Page Count

86

Department or Program

Department of Biological Sciences

Year Degree Awarded

2023


Included in

Biology Commons

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