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Description
Valley Fever (VF), is a potentially lethal fungal pneumonia caused by Coccidioides spp., which is estimated to cause ~15-30% of all community-acquired pneumonias in the highly endemic Greater Phoenix and Tucson areas of Arizona. However, an accurate antigen-based diagnostic is still lacking. In order to identify protein and glycan antigen

Valley Fever (VF), is a potentially lethal fungal pneumonia caused by Coccidioides spp., which is estimated to cause ~15-30% of all community-acquired pneumonias in the highly endemic Greater Phoenix and Tucson areas of Arizona. However, an accurate antigen-based diagnostic is still lacking. In order to identify protein and glycan antigen biomarkers of infection, I used a combination of genomics, proteomics and glycomics analyses to provide evidence of genus-specific proteins and glycosylations. The next goal was to determine if Coccidioides-specific glycans were present in biological samples from VF patients. Urine collected from 77 humans and 63 dogs were enriched for glycans and evaluated by mass spectrometry for Coccidioides-specific glycans and evaluated against a panel of normal donor urines, urines from patients infected with other fungi, and fungal cultures from closely related pneumonia-causing fungi. A combination of 6 glycan biomarkers was 100% sensitive and 100% specific in the diagnosis of human VF subjects, while only 3 glycan biomarkers were needed for 100% sensitivity and 100 specificity in the diagnosis of dog VF subject. Additionally, a blinded trial of 23 human urine samples was correctly able to classify urine samples with 93.3% sensitivity and 100% specificity. The results of this research provides evidence that Coccidioides genus-specific glycosylations have potential as antigens in diagnostic assays.
ContributorsMitchell, Natalie M (Author) / Lake, Douglas F (Thesis advisor) / Bean, Heather D (Committee member) / Grys, Thomas E (Committee member) / Magee, Dewey M (Committee member) / Arizona State University (Publisher)
Created2019
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Description
Coccidioidomycosis, or valley fever (VF), is a fungal infection caused by Coccidioides that is highly endemic in southern Arizona and central California. The antibody response to infection in combination with clinical presentation and radiographic findings are often used to diagnose disease, as a highly sensitive and specific antigen-based assay has

Coccidioidomycosis, or valley fever (VF), is a fungal infection caused by Coccidioides that is highly endemic in southern Arizona and central California. The antibody response to infection in combination with clinical presentation and radiographic findings are often used to diagnose disease, as a highly sensitive and specific antigen-based assay has yet to be developed and commercialized. In this dissertation, a panel of monoclonal antibodies (mAbs) was generated in an attempt to identify circulating antigen in VF-positive patients. Despite utilizing a mixture of antigens, almost all mAbs obtained were against chitinase 1 (CTS1), a protein previously identified as a main component in serodiagnostic reagents. While CTS1 was undoubtedly a dominant seroreactive antigen, it was not successfully detected in circulation in patient samples prompting a shift toward further understanding the importance of CTS1 in antibody-based diagnostic assays. Interestingly, depletion of this antigen from diagnostic antigen preparations resulted in complete loss of patient IgG reactivity by immunodiffusion. This finding encouraged the development of a rapid, 10-minute point-of-care test in lateral flow assay (LFA) format to exclusively detect anti-CTS1 antibodies from human and non-human animal patients with coccidioidal infection. A CTS1 LFA was developed that demonstrated 92.9% sensitivity and 97.7% specificity when compared to current quantitative serologic assays (complement fixation and immunodiffusion). A commercially available LFA that utilizes a proprietary mixture of antigens was shown to be less sensitive (64.3%) and less specific (79.1%). This result provides evidence that a single antigen can be used to detect antibodies consistently and accurately from patients with VF. The LFA presented here shows promise as a helpful tool to rule-in or rule-out a diagnosis of VF such that patients may avoid unnecessary antibacterial treatments, improving healthcare efficiency.
ContributorsGrill, Francisca J (Author) / Lake, Douglas F (Thesis advisor) / Magee, D Mitch (Committee member) / Grys, Thomas (Committee member) / Chen, Qiang (Committee member) / Arizona State University (Publisher)
Created2023