>> *To: The George Mason University Community* >> >> *Anne B. Verhoeven >> PhD Biosciences Candidate >> * >> *Date: Thursday June 17, 2010 >> Time: 10:30 a.m. >> Place: George Mason University >> ** Room 256, Bull Run Hall >> Prince William campus <http://www.gmu.edu/resources/visitors/findex.html> >> >> Dissertation Chair: Dr. Monique van Hoek >> Committee members: Dr. Emanuel Petricoin III, Dr. Yuntao Wu, Dr. Timothy Born* >> >> *Title: "An Analysis of Early Signaling Pathways Activated by /Francisella Tularensis/ Infection"* >> >> A copy of the dissertation is on reserve in the Johnson Center >> Library, Fairfax campus. The doctoral project will not be read at >> the meeting, but should be read in advance. >> >> All members of the George Mason University community are invited to >> attend.* >> * >> >> *ABSTRACT: >> * >> /Francisella tularensis /is a zoonotic, gram negative pathogen that >> in recent years has become a pathogen of increasing interest because >> of its bioterrorism implications. /Francisella /has been classified >> as a Type A pathogen by the CDC. It is capable of producing severe >> infection with doses as low as 10 organisms. The possible threat of >> /Francisella /as a biological weapon makes understanding its specific >> pathogenicity of utmost importance. >> /Francisella /is an intracellular pathogen that enters the cell >> through an unknown method. Infection from /Francisella /occurs in >> many different cell types, including macrophages, hepatocytes, and >> endothelial cells. Once in the cell, /Francisella /is encapsulated >> in a phagosome. Between 2-4 hours after the initial infection >> /Francisella /escapes the phagosome and proceeds to replicate in the >> hosts cytosol. Previous studies have demonstrated that /Francisella >> /inhibits the release of pro-inflammatory cytokines such as >> TNF-alpha, IL-1, IL-12, and IL-8, thus hampering the ability of the >> innate immune system to respond to infection. Also, there is an >> increase of IL-10 seen during /Francisella /infection. IL-10 is an >> anti-inflammatory cytokine that further decreases the innate immune >> system response. The lack of proper cytokine production might be >> caused by /Francisella/'s ability to block the TLR pathways, CR3 >> pathways, and the apoptosis pathways, further impeding the innate >> immune response. Interestingly, /Francisella /does not employ any >> known secretion systems, such as type III or type IV secretion >> systems that are commonly found in pathogenic bacteria. Nor does it >> produce toxins that could explain its ability to block cell signaling >> pathways. The mechanism used by /Francisella /to directly interact >> with host cell pathways is still unknown. >> *We hypothesize that by looking at specific pathways that are >> activated during infection of J774A.1 macrophages by /Francisella >> tularensis /LVS and /Francisella novicida, /we will be able to obtain >> a phosphorylation map of activated host cell responses which could >> lead to novel therapeutics.* The steps that we will use to accomplish >> this task are: 1) the use of Reverse Phase Protein Microarray >> analysis to generate a phosphorylation map of /Francisella /LVS and >> /Francisella novicida/ infection in J774A.1 cells, 2) validation of >> this map through western blots and analysis of previous reported data >> on specific signaling pathways, 3) comparison of different >> phosphorylation maps of /Francisella novicida /and /Francisella /LVS >> to determine differences between the strains, and 4) in a separate >> study, we will examing changes in gene expression in human lung >> epithelial cells through the use of microarrays to determine the >> difference in host cell gene transcription between uninfected A549 >> cells and /Francisella /LVS infected A549 cells. >> >> >> ###