ABSTRACT

Cryptococcus neoformans is an invasive fungal pathogen that is inhaled through the lungs and often results in fungal meningitis when it spreads. The CDC estimates the yearly burden of cryptococcal meningitis to be nearly one million cases with greater than 190,000 deaths. C. neoformans can be known as an opportunistic pathogen because it takes advantage of individuals with compromised immune systems, specifically ones with HIV. The lungs provide a low-glucose environment for C. neoformans, so it is likely that it must use alternative carbon sources to survive. It is hypothesized that acetate is utilized when glucose is not readily available. The goal of this research is to identify specific genes that are necessary for acetate utilization as they might be expected to play a role in pathogenesis.

This project investigated the gene CNAG_00613 (cytosine deaminase) which was one of fifteen genes identified in a genetic screen as being necessary for growth on acetate. Cytosine deaminase catalyzes the reaction that turns cytosine into uracil. This deamination reaction often results in mutations in microorganisms and inherited human diseases. The observation of expression data and analysis of function prediction was used to identify the role cytosine deaminase may play in C. neoformans infection.