Matching Items (2)
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 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
Description
Coccidioidomycosis, or Valley fever, is an endemic pneumonia of the arid and semi-arid regions of North and South America and is responsible for up to 30% of community-acquired pneumonias in endemic and highly populated areas of the United States southwest. The causative agents of Valley fever are the dimorphic fungi Coccidioides immitis and Coccidioides posadasii, which grow as mycelia in the environment and spherules within the lungs of vulnerable hosts. The current diagnostics for Valley fever are severely lacking due to poor sensitivity and invasiveness, strongly contributing to a 23-day median time-to-diagnosis. There is a critical need for sensitive and non-invasive diagnostics for identifying Valley fever lung infections. The long-term goal of my work is to substantially shorten the time-to-diagnosis for Valley fever through the development of sensitive and specific breath-based diagnostics for coccidioidomycosis lung infections. Herein, I characterized the volatile organic compounds (VOCs) produced by C. immitis and C. posadasii in vitro and evaluated the relationship of the volatile metabolomes to lifecycle. I explored the VOC profiles of bronchoalveolar lavage fluid (BALF) samples from mouse model lung infections of Valley fever. Finally, I investigated the VOC profiles of BALF from persons with community-acquired pneumonia. All VOCs were analyzed by headspace solid-phase microextraction and comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (HS-SPME-GC×GC-TOFMS). The volatile metabolomes were compared using a variety of statistical analyses. For the in vitro samples, I detected a total of 353 VOCs that were at least two-fold more abundant in a Coccidioides culture versus medium controls and found the volatile metabolome of Coccidioides is more dependent on lifecycle than species. The mouse BALF samples indicate that lung infection VOCs are correlated to cytokine production and classify mice based on their individual level of infection. From the human BALF samples, I identified VOCs that were able to differentiate between Coccidioides and bacterial pneumonia. Combined, these studies suggest that Coccidioides spp. and the host produce volatile metabolites that may yield biomarkers for a Valley fever breath test.
ContributorsHiggins Keppler, Emily (Author) / Bean, Heather D (Thesis advisor) / Barker, Bridget M (Committee member) / Borges, Chad R (Committee member) / Lake, Douglas F (Committee member) / Arizona State University (Publisher)
Created2023