Dissertation
THE CONTRIBUTION OF SPI-13 TO THE METABOLIC FITNESS AND PATHOGENCITY OF SALMONELLA ENTERITIDIS
Doctor of Philosophy (PhD), Washington State University
01/2016
Handle:
https://hdl.handle.net/2376/116737
Abstract
Salmonella Pathogenicity Island-13 (SPI-13) is a polymorphic genomic island found in most sequenced Salmonella genomes. SPI-13 is of particular interest because; (i) inactivation of genes within SPI-13 in three major Salmonella serotypes results in negative selection in different hosts, suggesting that SPI-13 may contribute to in vivo competitive fitness of Salmonella, (ii) bioinformatics analysis of SPI-13 shows that many SPI-13 genes are likely related to metabolism, suggesting that SPI-13 may contribute to metabolic fitness of Salmonella, and (iii) the gene composition of SPI-13 varies widely between different Salmonella serotypes which is presumably related to host adaptation. We hypothesized that SPI-13 contributes to the pathogenicity and metabolic fitness of Salmonella Enteritidis (SE). To test this hypothesis, we compared the pathogenicity of a wild-type (WT) and a mutant strain of Salmonella Enteritidis (SE) lacking SPI-13 (ΔSPI-13) in orally inoculated chickens and mice. The ΔSPI-13 colonized the organs (intestine, liver and spleen) of mice at significantly lower levels, induced less intestinal inflammation, and exhibited reduced survival in cultured murine macrophages when compared with the WT. However, the infection kinetics of ΔSPI-13 in chickens and the intra-macrophage survival in avian macrophages was not significantly different from WT. We also compared the respiratory activity (RA) of ΔSPI-13 and WT for 947 different metabolic phenotypes by OmniLog phenotype microarray (Biolog, USA). The ΔSPI-13 displayed significantly lower RA and impaired growth when D-glucuronic acid was provided as a sole source of carbon or tyramine as the sole source of carbon and/or nitrogen. Systematic deletion of ten individual operons (Op1-Op10) within SPI-13 revealed that Op-10 (SEN2977), encoding a predicted hexuronate transporter, is required for efficient utilization of D-glucuronic acid. However, deletion of Op4 (SEN2967), Op6 (SEN2970-SEN2971) or Op7 (SEN2972) resulted in impaired utilization of tyramine as sole carbon and nitrogen source, suggesting that tyramine utilization is governed by multiple genes within SPI-13. These data suggest that SPI-13 contributes to pathogenicity of SE in mice, but not in chickens. The SPI-13 also plays a role in utilization of D-glucuronic acid and tyramine. It is possible that the observed virulence attenuation is linked to metabolic fitness of SE in vivo.
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Details
- Title
- THE CONTRIBUTION OF SPI-13 TO THE METABOLIC FITNESS AND PATHOGENCITY OF SALMONELLA ENTERITIDIS
- Creators
- Jacob Robert Elder
- Contributors
- Devendra H Shah (Advisor)Leigh Knodler (Committee Member)Kelly A Brayton (Committee Member)Subramaniam Srikumaran (Committee Member)Jean Guard (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Veterinary Medicine, College of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 102
- Identifiers
- 99900581520801842
- Language
- English
- Resource Type
- Dissertation