Salmonella enterica remains a major source of human and animal infection worldwide. Despite the identification of over 2,500 Salmonella serovars, the majority of our knowledge on Salmonella pathogenicity and host response mechanisms has developed through studies on a limited number of strains from a few serovars. Strain variation within and between serovars has not been fully investigated. Here, 18 Salmonella strains representing six serovars frequently recovered from human cases of infection have been characterised. All strains exhibited similar growth and motility characteristics but significant variation was observed in their abilities to form biofilms and to invade epithelial cells. Strain heterogeneity was evident both within and between serovars. Furthermore, the overall invasion profiles observed were conserved between epithelial cell lines and did not alter with the application of mild centrifugation. GFP reporter constructs confirmed that the Salmonella Pathogenicity Island (SPI) 1 structural gene, prgH, was only expressed in a subpopulation of Salmonella and this bistable expression returned after populations were sorted based on GFP expression and then allowed to recover. GFP and LacZ reporter constructs revealed a close correlation between SPI-l prgH promoter transcription at")d invasion in MDCK I cells at late log phase in the majority of strains examined, with low invasion associated with low levels of prgH promoter activity. Strains which lacked the effector protein, Salmonella outer protein E1 (SopEl) induced slower and smaller membrane ruffles in comparison to SopEl positive strain (SopEl +) S. Tm SL1344. However some SopE1+ strains were observed inducing membrane ruffles with comparable induction kinetics and ruffle diameters as strains which lacked SopEl. The presence of SopEl, large membrane ruffles or the fast induction of membrane ruffles did not ,correlate with invasion. These data demonstrate that significant strain variation exists between strains and serovars which may have important implications for Salmonella and other microbial infection studies
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:665154 |
| Date | January 2014 |
| Creators | Malt, Layla |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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