Identification of novel Salmonella Typhimurium genes required for survival during intestinal inflammation : a dissertation /
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[College Station, Tex.] :
[Texas A&M University System Health Science Center],
[2013]
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| Subjects: |
| Abstract: | ABSTRACT: Bovine ligated ileal loops provide the best model to examine Salmonella Typhimurium genes required for survival during the early stages of infection, as humans and cattle develop very similar intestinal pathogenesis in response to the organism. Utilizing pools of mutants, both single gene and multi-gene deletion mutants, much of the S. Typhimurium genome can be screened simultaneously. A library consisting of multi-gene deletion mutants was screened in ligated ileal loops in calves. Regions of the genome required for survival in this model were identified in mucus and tissue samples using microarray analysis. STM1187-90 was one such region identified as under selection in both mucus and tissue. A [delta]STM1188 mutant was confirmed to poorly colonize the intestinal mucus and tissue in the presence of inflammation in competitive infections with the wild type. Complementation in trans reversed the phenotype of the [delta]STM1188 mutant. The phenotype of the [delta]STM1188 mutant was replicated and complemented in trans in the murine colitis model. STM1188 is a Salmonella specific gene whose protein product we show to be located in the inner membrane. This gene is absent in host-adapted serovars S.Typhi and S. Paratyphi A. Mutation of the putative lipobox cysteine to alanine resulted in mislocalization of STM1188C24A to the cytoplasm, and the inability to complement [delta]STM1188 in trans in mice. A second screen of a single gene deletion pool (SGD) identified many novel genes with potential roles during inflammation as well as many predicted genes with defined roles during the early stages of infection. Several novel gene phenotypes were confirmed and subsequently complemented in competitive infections with wild type. [delta]hilE was identified during SGD screening and confirmed in bovine ligated ileal loops as being selected against during competitive infections with extensive inflammation, however, it was not selected against when the inflammatory immune response was limited. HilE has been previously shown to negatively regulate SPI-1 expression. Utilizing the murine colitis model, the [delta]hilE phenotype was confirmed and complemented during competitive infection with wild type. By using [beta]-galactosidase assays, [delta]hilE was confirmed to overexpress SPI-1, however, surprisingly [delta]hilE also overexpressed SPI-2 during SPI-1 inducing conditions. In the current studies we performed Salmonella screens in bovine ligated ileal loops and confirmed novel virulence genes required for survival during inflammation. |
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| Item Description: | Vita. "Major Subject: Biomedical Sciences". "Submitted to the Office of Research and Graduate Studies of The Texas A&M University Health Science Center In partial fulfillment of the requirements for the degree of Doctor of Philosopy May 2013." Approved as to style and content by: Helene Andrews-Polymenis, Jonathon Skare, James Samuel, L. Garry Adams, Vernon Tesh. |
| Physical Description: | xv, 118 leaves : illustrations (some color) ; 28 cm. |
| Bibliography: | Includes bibliographical references (leaves 91-116). |