Date of Award
5-1-2024
Degree Name
Master of Science
Department
Molecular Biology Microbiology and Biochemistry
First Advisor
Vargas-Muniz, José
Second Advisor
Fisher, Derek
Abstract
Aspergillus fumigatus is the major etiology of invasive aspergillosis, a leading cause of death in immunocompromised patients. Septins are conserved GTPases that could be mediating host-spore interactions in A. fumigatus. To test this hypothesis, we are using a combination of microscopy techniques and cell culture-based methods. Using Atomic Force Microscopy, we found that spores from the ∆aspB strain have a disorganized rodlet layer compared to the parent strain. Disorganized rodlet layer can lead to an increase in immune recognition of common pathogen associated molecular patterns (PAMPs), chitin and β-glucan. It is unknown whether the increase in immune recognition of ∆aspB spores is due to more exposure to the host or if they total quantity of PAMPs has increased. To test this, we used several staining methods to compare total and exposed levels of PAMPs in the conidia. Our work shows that there is an increase in exposed chitin and total levels of chitin and β-glucan. To evaluate how this plays a role in vitro, we first exposed macrophage-like cells (J744.1) to septin deletion strain’s spores and measured the TNF-a to determine spore immunogenicity using an ELISA. As expected, only the deletions that abolish all septin complexes had a significant increase in TNF-a. Then, we determine how effective macrophages were at killing the spores. We found that the deletion strains were more susceptible to killing by the macrophages. A murine study revealed that ∆aspB infection results in more lung inflammation than the wildtype. Taken together, these results suggest the septin cytoskeleton is involved in A. fumigatus spore cell wall organization and immune evasion.
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