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Coccidioides the causative agent of Valley Fever: characterization of parasitic behaviors in the lab and in the field

Mead, Heather Lynn (2021) Coccidioides the causative agent of Valley Fever: characterization of parasitic behaviors in the lab and in the field. Doctoral thesis, Northern Arizona University.

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The disease San Joaquin Valley Fever (Valley fever, coccidioidomycosis) is caused by the inhalation of arthroconidia of Coccidioides species, which are dimorphic fungi found in arid desert soil. My dissertation research is focused on using microbiological, molecular, and epidemiological tools to investigate the pathogenetic behaviors of these important fungal pathogens. After asexual arthroconidia are exposed the host respiratory system they transform into pathogenic structures termed spherules. The molecular determinants responsible for parasitic morphogenesis are not well characterized. In chapter two, my collaborators and I provide a detailed account of spherule growth using both species of Coccidioides. We investigated spherule density and diameter over time, thus providing a valuable tool which is easily reproducible and can be applied to future studies examining spherule development. Within the host, Coccidioides spherules cyclically rupture and release small structures called endospores. The molecular signaling pathways involved in this key step of development and establishment of infection remain largely obscure. In chapter three, we describe the transcriptome and volatile metabolome active during spherule remodeling and endospore formation. Subsequently, expression of genes of interest were confirmed in an in vivo model using NanoString technology. In summary, our results specify the first list of key target genes for future functional characterization that are active during endospore formation, a critical step in coccidioidomycosis. In chapter four, we conduct the first focused investigation of coccidioidomycosis in Northern Arizona. Arizona has some of the highest number of confirmed cases of coccidioidomycosis nationwide each year, which predominantly occur in the southern part of the state. In moderately or suspected endemic regions such as Northern Arizona, the risk of acquiring disease is lower, but still prevalent. The region may contain habitat which supports Coccidioides survival, but little focus has been placed on the current disease burden. We investigate susceptibility of various populations, geographic origins of infection using genomic epidemiology, and the potential for regions of northern Arizona to support the pathogen. Our goal is to document the region-specific implications for human health in regard to Valley fever, providing a reference for future investigations and public health awareness campaigns.

Item Type: Thesis (Doctoral)
Publisher’s Statement: © Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords: Coccidioides species; coccidioidomycosis; dimorphic fungi; fungal pathogen; Valley Fever
Subjects: R Medicine > RC Internal medicine
MeSH Subjects: C Diseases > C02 Virus Diseases
NAU Depositing Author Academic Status: Student
Department/Unit: Graduate College > Theses and Dissertations
College of the Environment, Forestry, and Natural Sciences > Biological Sciences
Date Deposited: 03 Mar 2022 19:12
Last Modified: 03 Mar 2022 19:12
URI: https://openknowledge.nau.edu/id/eprint/5795

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