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"The Proteomic Profile of Aspergillus fumigatus"

Steven E. Cagas
Department of Microbiology and Molecular Genetics
B.S. 2003, Rutgers University

Thesis Advisor: David S. Perlin, Ph.D.
Department of Microbiology and Molecular Genetics

Thursday, January 27, 2011
ICPH Auditorium, 10:00 a.m.


Aspergillus fumigatus is a saprophytic fungus that causes a range of diseases in humans. It has approximately 10,000 open reading frames, and, from our studies, at any one particular time, several thousand proteins are being expressed. Most proteins are expressed only under a particular set of conditions. Some of these proteins can be exploited as biomarkers for various disease states. We hypothesize that biomarkers for early infection and efficacy of treatment can be identified by using various proteomic methods. In this respect, we have chosen to examine, in detail, various cellular compartments including total membranes, cell wall components, cytoplasmic and secreted proteins. To provide a qualitative assessment of expressed proteins, we have used conventional 2D gel electrophoresis. This approach provides a gross overview of abundant proteins but is limited in scope and quantitation. In addition, this system is limited by the ability to run the gels and excise and analyze all protein spots manually. A more comprehensive and quantitative approach was undertaken using isobaric tagging. The gel-free system called iTRAQ has been implemented to identify large numbers of proteins with higher confidence levels. Proteins that are expressed early in development can be used as biomarkers of active infection since all people are colonized with conidia. Furthermore, as a consequence of therapy, proteins that increase or decrease during antifungal treatment can be scored as potential markers for treatment efficacy. As the number of people that can be infected with Aspergillus increases due to increased immune suppression, the demand for these types of biomarkers is very high. Very few biomarkers are available for Aspergillus and all are present during a later phase of infection where treatments and outcomes become dire. If treatment can be started earlier, patient outcome is better. Current efficacy markers are usually more invasive and if an easier, faster, molecular-based assay can be used, both the research community and patients would benefit.

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