Browsing by Subject "agr"
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Item Lethality of Staphylococcus in Murine Pneumonia is Due to Alpha-Toxin and Other Secreted Factors Regulated by AGR and SAR(2003-08-01) Overheim, Katie A.; Dan Dimitrijevich; Glenn Dillon; James CaffreyOverheim, Katie A., Lethality of Staphlococcus aureus in Murine Pneumonia is Due to Alpha-Toxin and Other Secreted Factors Regulated by agr and sar. Doctor of Philosophy (Biomedical Sciences), August, 2003, 91 pp, 6 Tables, 9 illustrations, bibliography, 106. The purpose of these studies was to determine if the S. aureus global regulators agr and sar play a role in staphylococcal pneumonia and if the virulence factors regulated by them contributed to the severity of staphylococcal pneumonia. To determine this, we established a pneumonia model in mice in order to identify if S. aureus global regulators agr and sar play a role in the pathogenesis of staphylococcal pneumonia. As well, we took steps to identify the extracellular factors responsible for the lethality in a murine model of staphylococcal pneumonia and determine if these factors involved in disease process could be used as targets for immune therapy. My work revealed that lethal pneumonia in a mouse model is dependent on the S. aureus global regulators agr and sar. This study also revealed that the lethality associated with our model is due to secreted factors, regulated by S. aureus global regulators agr and sar. Further investigation demonstrated the alpha-toxin is a major virulence factor involved in the lethality in our model. By generating an alpha-toxin deficient strain in S. aureus RN6390, we show a reduced virulence in our disease model. As well, antiserum to alpha-toxin, when administered with a lethal dose of S. aureus RN6390, we show a reduced virulence in our disease model. As well, antiserum to alpha-toxin, when administered a lethal dose of S. aureus RN6390, we show a reduced virulence in our disease model. As well, antiserum to alpha-toxin, when administered with a lethal dose of S. aureus RN6390 protected animals from death. By evaluating the role of alpha-toxin’s ability to contribute to lethality, we assessed numerous strains of S. aureus in our pneumonia model. We discovered that there was a correlation to alpha-toxin production levels and lethality in our pneumonia model. However, our study also demonstrated that alpha-toxin is not the only factor involved in the disease process.Item The Effects of Two Staphylococcal Global Regulators (agr and sar) on Acid Phosphatase production in Staphylococcus aureus(2003-05-01) Agouna-Deciat, Bahrka Olivier; Jerry Simecka; Michael SmithAgouna-Deciat, B. Olivier, The Effect of Two Staphylococcal Global Regulators (agr and sar) on Acid Phosphatase Production in Staphylococcus aureus. Master of Science (Molecular Biology and Immunology), May 2003, 75 pp., 3 tables, 14 illustrations, 16 titles. Staphylococcus aureus produces an extensive number of cell-surface associated proteins, extracellular proteins and enzymes that contribute to its virulence. The key to better preventative or curative approaches resides in identifying and targeting the very genes and their products that play major roles in the survival of the bacteria within the host and the establishment of diseases. Two well known regulatory loci, the accessory gene regulatory (agr) and the staphylococcal accessory regulator (sar), control the expression of most S. aureus genes that encode for its virulence factors. Other virulence gene regulators have recently been isolated. Over 40 proteins and enzymes produced by S. aureus have been identified and several of them have been linked to staphylococcal pathogenesis. In this study, we attempt to determine the role of agr and sar in the regulation of the production of a secreted staphylococcal acid phosphatase (Sap) suspected to contribute to virulence.