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Multiple Antibiotic Resistant Staphylococcus Spp. In Environmental Settings, Stephen Shost
Multiple Antibiotic Resistant Staphylococcus Spp. In Environmental Settings, Stephen Shost
Legacy Theses & Dissertations (2009 - 2024)
Ninety staphylococci carrying the mecA gene, including 17 strains of methicillin-resistant Staphylococcus aureus (MRSA), were isolated from environmental settings within New York State. Waterborne staphylococci harboring mecA were isolated from multiple sources: the Hudson River near a combined sewage overflow; urban streams; freshwater and marine beaches; a swimming pool; swimming pool decks; combined sewage; as well as wastewater treatment plant (WWTP) primary sewage influent, mixed liquor, aeration water, and final (unchlorinated) effluent. Environmental MRSA strains were isolated from beach water (n=3); swimming pool deck water (n=1); Hudson River water (n=2); combined sewage (n=3); as well as wastewater treatment plant mixed …
Effect Of Anti-Lipopolysaccharide Iga Antibodies On The Virulence And Physiology Of Salmonella Enterica And Shigella Flexneri, Stephen J. Forbes
Effect Of Anti-Lipopolysaccharide Iga Antibodies On The Virulence And Physiology Of Salmonella Enterica And Shigella Flexneri, Stephen J. Forbes
Legacy Theses & Dissertations (2009 - 2024)
Secretory IgA (SIgA) antibodies directed against the serotype-specific, O-antigen of lipopolysaccharide (LPS) are the primary determinants of mucosal immunity to enteric bacterial pathogens, including of Salmonella enterica serovar Typhimurium and Shigella flexneri. While the singular importance of SIgA in preventing enteric infections is recognized, the underlying mechanisms by which these antibodies protect the mucosal epithelium remains poorly understood. In this study, I demonstrated that Sal4, a protective, anti-LPS specific monoclonal IgA, is a potent inhibitor of S. Typhimurium flagella-based motility and type three secretion (T3S) mediated entry into epithelial cells. Sal4's effects on motility and invasion occurred rapidly (<15 min), and were independent of agglutination. I also present evidence the protective anti-LPS, monoclonal IgA, IgAC5, reduced S. flexneri T3S of IpaB and IpaC. Concurrent with the IgA-induced reduction in T3S, there was a decrease in both the proton motive force and ATP levels in both bacterial species examined. I also report that Sal4 and IgAC5 have effects on the bacterial envelope. Scanning, transmission, and cyro-electron microscopy revealed dramatic antibody-mediated alterations in the topology of the outer membrane (OM) of S.Typhimurium and S. flexneri. Furthermore, Sal4-treatment caused a ~5 fold increase in O-antigen, and elevated levels of lipid A, released into culture supernatants, consistent with the loss of LPS. Correspondingly, the OM of antibody-treated bacteria was ~50% more permeable than control cells. Based on these data, I proposed that Sal4 binding to the LPS destabilizes the outer leaflet of the OM of S. Typhimurium, thereby compromising the integrity of the bacterial envelope, disrupting bioenergetics by physical and/or mechanical stress, and arresting both flagella-based motility and T3S. This study reveals a previously unrecognized capacity of SIgA to "disarm" enteric pathogens in mucosal secretions, thereby preventing colonization and invasion of the intestinal epithelium.
Identification Of B-Cell Epitopes On Domain 4 Of Anthrax Protective Antigen, Cassandra D. Kelly-Cirino
Identification Of B-Cell Epitopes On Domain 4 Of Anthrax Protective Antigen, Cassandra D. Kelly-Cirino
Legacy Theses & Dissertations (2009 - 2024)
Protective Antigen (PA) is the receptor binding subunit common to both Lethal (LT) and Edema (ET) toxins, which contribute to the mortality associated with Bacillus anthracis infection. While recombinant PA (rPA) is likely to be an important constituent of second generation anthrax vaccines, evaluating the effectiveness of candidate vaccines is currently difficult, because the specific B cell epitopes involved in toxin neutralization have not been completely defined. The only well characterized antibody, 14B7, has been shown to disrupt the association of PA with the anthrax toxin receptors (ATR) by binding to domain 4 of PA. I hypothesized that other domain …
Generation And Maintenance Of Protective Igm Responses During Intracellular Bacterial Infection, Rachael Denise Racine
Generation And Maintenance Of Protective Igm Responses During Intracellular Bacterial Infection, Rachael Denise Racine
Legacy Theses & Dissertations (2009 - 2024)
It is widely accepted that IgM provides the first line of defense against during microbial infection prior to the generation of high-affinity, isotype-switched antibodies, which is the hallmark of long-lived lived immunity and immunological memory. The overall objective of these studies was to address the role of IgM in the generation and maintenance of protective immunity during intracellular bacterial infection. We have identified a population of CD11clo plasmablasts that were responsible for nearly all of the antigen-specific IgM production in the spleen. Moreover, selective depletion of the CD11c-expressing B cells during acute infection resulted in a complete loss in the …
The Impact Of Environment On Virulence Of The Pathogenic Yeast Cryptococcus Gattii, Deborah Jean Springer
The Impact Of Environment On Virulence Of The Pathogenic Yeast Cryptococcus Gattii, Deborah Jean Springer
Legacy Theses & Dissertations (2009 - 2024)
Four serotypes of Cryptococcus are responsible for most human and animal infections. C. gattii , serotype B and C, are the primary the causative agent of cryptococcosis in immune competent individuals whilst, C. neoformans var. neoformans serotype D, and C. neoformans var. grubii serotype A are most prevalent in immunocompromised hosts world-wide. C. gattii is recognized as a species distinct from C. neoformans based on differences in clinical manifestations, morphology, biological characteristics, and environmental niche. We used the plant model Arabidopsis thaliana plants and plant derived substrates as a model to explore C. gattii interactions in its ecological niche. C. …