The ability of Salmonella to invade and survive in epithelial cells is critical to their virulence and for their use in vaccine development. Salmonella encode two protein secretion systems that inject a variety of proteins into host cells. Recent in vitro studies have revealed that some of these secreted proteins affect cell function by interacting with host cell proteins but their precise role in pathogenesis is not yet known. Similarly the role of Salmonella surface proteins in infection of intestinal epithelia remains to be fully elucidated.
A research project is available to examine how Salmonella proteins interact with epithelial cells and contribute to intestinal infection. Comparison will be made of the ability of Salmonella strains lacking one or more secreted or surface proteins to enter and survive in epithelial cells. We will also apply molecular cell biology techniques to examine the role of host cell proteins in invasion and subsequent intracellular trafficking and replication.
Techniques to be used include: 1) imaging changes in cytoskeletal and trafficking proteins and cellular morphology during infection by confocal microscopy, immunofluorescence and electron microscopy, 2) mutation of bacterial genes encoding secreted proteins, 3) expression of GFP-tagged and functionally modified forms of proteins in eukaryotic cells, 4) suppression of host protein expression using siRNA, 5) use of GFP reporter constructs to localise Salmonella and investigate virulence gene expression at the single cell level.
This research project is appropriate for someone interested in applying molecular biology and cell imaging techniques to the study of microbial pathogenesis. It will make major use of imaging systems (including confocal and electron microscopes) in our exceptionally well-equipped Bioimaging Facility.
1. Clark, L., Perrett, C.A., Malt, L., Harward, C., Humphrey, S., Jepson, C.A., Martinez-Argudo, I., Carney, L.J., La Ragione, R.M., Humphrey, T.J. & Jepson, M.A. (2011) Differences in Salmonella enterica serovar Typhimurium strain invasiveness are associated with heterogeneity in SPI-1 gene expression. Microbiology 157: 2072-83
2. Perrett, C.A. & Jepson, M.A. (2009) Regulation of Salmonella-induced membrane ruffling by SipA differs in strains lacking other effectors. Cellular Microbiology 11: 475-87
3. Bujny, M.V., Ewels, P., Humphrey, S., Attar, N., Jepson, M.A. & Cullen, P.J. (2008) Tubular-based early phase re-modelling of the Salmonella-containing vacuole is dependent upon sorting nexin-1. J. Cell Sci. 121: 2027-36
4. Martinez-Argudo, I. & Jepson, M.A. (2008) Salmonella translocates across an in vitro M cell model independently of SPI-1 and SPI-2. Microbiology 154: 3887-94