Dissertation
ELUCIDATION OF CAMPYLOBACTER JEJUNI PATHOGENESIS IN HUMANS AND COMMENSAL COLONIZATION IN CHICKENS
Doctor of Philosophy (PhD), Washington State University
01/2011
Handle:
https://hdl.handle.net/2376/3510
Abstract
Campylobacter jejuni is the most common culture-proven cause of bacterial foodborne illness in the United States and worldwide. Campylobacter-mediated gastroenteritis, campylobacteriosis, is characterized by diarrhea containing blood and leukocytes, abdominal cramps, and fever. While C. jejuni causes disease in humans, it is able to colonize the gastrointestinal tract of birds without causing illness. This dissertation is composed of two studies that examine the virulence mechanisms of C. jejuni in human disease, and two studies
that examine the commensal colonization of C. jejuni in broiler chicks.
The first study examined the secretion properties of the major (FlaA) and minor (FlaB)
flagellar filament proteins, which are secreted through the flagellar type III secretion system (T3SS), and are recognized by an amino-terminal sequence in protein. We found that specific residues in the amino-termini of FlaA and FlaB dictated the efficiency of export through the flagellum, a novel mechanism by which bacteria can regulate the export efficiency of proteins. The second study demonstrated that the flagellar T3SS of C. jejuni is used to deliver the Campylobacter invasion antigens (Cia), virulence proteins, to host cells. This result is a paradigm shift in our understanding of bacterial pathogenesis, as it was previously thought that only injectisome T3SS were capable of delivering proteins to the cytosol of mammalian cells.
The third study determined the distribution of putative adhesin genes in C. jejuni, and the relative contribution of each gene to the colonization of chickens. The majority of C. jejuni strains possessed all seven putative adhesins, and only the presence of jlpA and capA varied between strains. The CadF and FlpA proteins contribute most to the binding of INT 407 epithelial cells, and are required for colonization of broiler chicks. The fourth study examined the use of Lactobacillus strains as potential probiotics to reduce the colonization of C. jejuni in
broiler chicks. Each strain of Lactobacillus tested provided some protection against colonization. The predominant mechanism of inhibition of C. jejuni by Lactobacillus appears to be the production of lactic acid. Using novel vibrational spectroscopy techniques, we found that lactic
acid altered the membrane properties of C. jejuni.
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Details
- Title
- ELUCIDATION OF CAMPYLOBACTER JEJUNI PATHOGENESIS IN HUMANS AND COMMENSAL COLONIZATION IN CHICKENS
- Creators
- Jason Neal-McKinney
- Contributors
- Michael E. Konkel (Advisor)Michael E. Konkel (Committee Member)Michael Kahn (Committee Member)Lisa Gloss (Committee Member)Scott Minnich (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Molecular Biosciences, School of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 259
- Identifiers
- 99900581658201842
- Language
- English
- Resource Type
- Dissertation