Document Type

Honors Thesis

Major

Biochemistry

Advisor(s)

Benjamin King

Committee Members

Edward Bernard, R.W. Estela, Sally Molloy, Robert Wheeler

Graduation Year

May 2020

Publication Date

Spring 5-2020

Abstract

Seasonal influenza A virus (IAV) infections and their associated respiratory diseases are the cause of an estimated 650,000 deaths each year, according to the World Health Organization. The zebrafish (Danio rerio) is a powerful vertebrate model to study innate immune function and host-pathogen interactions as the function of neutrophils and other phagocytes can be characterized in vivo. Preliminary studies have shown an increase in neutrophil respiratory burst activity to eliminate the invading pathogen, yet little is known of all of the mechanisms involved in neutrophil function. The NADPH oxidase complex, of which neutrophil cytosolic factor 1 (Ncf1) is a key component, regulates reactive oxygen species (ROS) to control neutrophil response to viral infection. Although necessary to fight infection, this elicits a hyperinflammatory response that can damage the infected host epithelial tissue, leaving high-risk individuals with increased mortality rates. Our hypothesis is that a fully functional Ncf1 protein is required for neutrophil function, but morpholino knockdown of the gene will limit the amount of damaging ROS hyperinflammation in host tissue. Our preliminary studies of systemic IAV infected embryos indicate that the survival of ncf1 morphants was increased compared to standard morphant control groups. Fluorescence confocal imaging and TCID50 assays reveal a decreased viral burden in ncf1 morphant groups compared to control morphant groups over a span of 96 hours post-infection. Finally, qRT-PCR studies assay the expression of nrf2, mxa, and cxcl8b revealing decreased expression of each gene in ncf1 morphants compared to controls. These studies aim to increase our understanding of neutrophil function that may eventually lead to new therapies for treating IAV infection.

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