LE3 .A278 2018

2018

Walker, Allison

Acadia University

Bachelor of Science

Honours

Biology

Biology

Aspergillus fumigatus Fresen (Trichocomaceae, Ascomycota) is a ubiquitous, saprophytic fungus and the causal agent of invasive aspergillosis (IA), one of the most serious clinical invasive fungal infections.Reports of increased prevalence of antifungal resistant strains of A. fumigatus have led to research on genes and proteins that could be used as potential targets for future antifungal treatments. Susceptibility screening was conducted on glycosylphosphatidylinositol (GPI) anchored protein, chitinase, and sterol regulatory element-binding protein (SrbA) gene knockout (KO) strains of A. fumigatus using the common triazole antifungal drug Itraconazole (ITC). Gene KO strains that displayed an abnormal minimum inhibitory concentration (MIC) in the presence of the antifungal drug were selected to undergo proteomic analysis consisting of liquid chromatography coupled with mass spectroscopy (LC-MS/MS) and two-dimensional (2D) differential gel electrophoresis (DIGE). The GPI-anchored protein, and chitinase gene KO strains tested displayed no observable variation in their MIC after exposure to ITC. The ΔsrbA mutant strain analyzed exhibited a MIC of 0.0625mg/ L, which differed from the wild-type strain MIC of 0.5mg/L. The 2-D DIGE electrophoresis revealed nine protein spots with variation in abundances between the ΔsrbA mutant strain and the wild-type strain. Comparative LC-MS/MS analysis revealed significant variation in protein abundances between the ΔsrbA mutant strain and the wild-type strain of A. fumigatus. Variation in the abundance of proteins related to mitochondrial function, iron regulation, and fatty acid biosynthesis, as well as DNA damage response, drug transport, and mycotoxin production represent interesting findings related to the functioning of the ΔsrbA mutant strain. These findings provide insights into metabolic pathways and proteins that have altered regulation in the ΔsrbA strain of A. fumigatus during triazole stress, and present an opportunity for future research to explore their uses as therapeutic targets and to broaden our understanding of the mechanisms of antifungal drug resistance.

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https://scholar.acadiau.ca/islandora/object/theses:2646