Dissertation
Host Gene Variants and Sting-mediated Reactive Oxygen Species Affect Drosophila melanogaster Survival During Coxiella burnetii Infection
Washington State University
Doctor of Philosophy (PhD), Washington State University
2022
DOI:
https://doi.org/10.7273/000004989
Abstract
The first line of defense against pathogens is referred to as innate immunity. At the molecular level, innate immunity begins when pathogens are recognized by immune receptors which then activate signaling cascades to protect the host. Immune receptors like STimulator of Interferon Genes (STING), recognize cyclic-dinucleotides synthesized by cyclic GMP-AMP synthase (cGAS) upon detection of cytosolic DNA. STING is one of many nucleic acid sensors that have significant roles in human health as they protect against a wide variety of pathogens. Chapter Two in this body of work reviews known RNA and DNA nucleic acid sensors by focusing on their respective activation by different viruses and bacteria. Chapters Three and Four focus on the Gram-negative bacterium Coxiella burnetii, which is the causative agent of Query (Q) fever in humans and coxiellosis in livestock. It is known that C. burnetii evades host detection through its lipopolysaccharide O-antigen which is undetected by immunocompetent hosts. Nonetheless, little is known about specific host genes that confer susceptibility or tolerance to infection, and how specific host proteins like STING are needed for host survival. C. burnetii biomedical research is hindered due to the biosafety-level 3 facility requirement to work with the infectious strain. Moreover, there is a limited number of animal models available to study host-pathogen interactions during infection. We investigated C. burnetii infection using Drosophila melanogaster and the attenuated NMII strain of bacteria to allow us to study live host-pathogen interactions and innate immunity in a biosafety-level 2 facility. In the first study, we performed a genetic screen by injecting over 30,000 fruit flies from the Drosophila Genetic Reference Panel. We validated 15 novel fly host gene variants that confer susceptibility or tolerance to C. burnetii infection. In the second study, we utilized a CRISPR-Cas9 Sting-deleted fly line. We found that the role of Drosophila Sting during C. burnetii infection is to regulate reactive oxygen species. Together, these studies employed two complementary approaches to investigate live host-pathogen interactions during C. burnetii infection in D. melanogaster that highlight the importance of performing biomedical research with specific translatable human impact for challenging pathogens like C. burnetii.
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Details
- Title
- Host Gene Variants and Sting-mediated Reactive Oxygen Species Affect Drosophila melanogaster Survival During Coxiella burnetii Infection
- Creators
- Rosa Marena Guzman
- Contributors
- Alan G Goodman (Advisor)Erika Offerdahl (Committee Member)Anders Omsland (Committee Member)Jennifer L Watts (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Molecular Biosciences, School of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 318
- Identifiers
- 99901019236601842
- Language
- English
- Resource Type
- Dissertation