Research focus: |
Lehrstuhl für Mikrobiologie
Am Hubland, 97074 Würzburg Mail: goebel@biozentrum.uni-wuerzburg.de Url: http://www.biozentrum.uni-wuerzburg.de/microbiology/ |
Scientific members:
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Research foci (and basic equipment-based research projects):
Research at the Chair of Microbiology is carried out with the aim of understanding at the molecular level the virulence mechanisms of Listeria monocytogenes, a gram-positive, facultative intracellular bacterium which causes systemic infections (listeriosis) in humans and animals.
In the period under report our research was financed by the Deutsche Forschungsgemeinschaft (DFG Schwerpunktprogramme, Normalverfahren and Sonderforschungsbereiche), the Federal Ministry for Research (BMBF) and the European Union and dealt with the following aspects:
- Invasion of L. monocytogenes in different animal and human cell types
- Prerequisites for the growth of the bacteria in the cytosol of the eukaryotic host cell
- Differential regulation of virulence genes
- Comparative genomics of pathogenic and nonpathogenic Listeria species
- Development of bacterial carrier systems for the generation of recombinant life vaccines
Results:
Using different in vitro cell culture systems we could show that human hematopoietic stem cells in the bone marrow which are the precursors of dendritic cells and macrophages (the most important host cells of L. monocytogenes), are resistant to L. monocytogenes. Only at later stages of development they will allow the infection with L. monocytogenes. The uptake into normally non-phagocytic cells (epithelial cells, endothelial cells and hepatocytes were investigated) is mediated by sevaral Listeria-specific surface proteins (internalins). Here we could show that internalin B is sufficient for the uptake of L. monocytogenes by several host cells like enothelial cells and hepatocytes. However, in the case of uptake of L. monocytogenes by cells requiring internalin A, the support by other internalins is needed some of which were initially described and characterized in our laboratory.
By direct microinjection of bacteria into the cytosol of epithelial cells we could demonstrate that this cellular compartment does not represent a suitable environment allowing the growth of heterotrophic bacteria. Instead, specific physiological adaptations by the bacteria are needed. In the case of L. monocytogenes a specifically regulated gene which is needed for intracellular growth was identified which codes for a hexose-phosphate transporter (hpt).
The most of the known virulence genes of L. monocytogenes, including the recently identified hpt gene are activated on the transcriptional level by a central transcriptional regulator, called PrfA. This activation is differentially regulated and allows a timely and spatial control of expression of specific virulence factors during infection. An in vitro-transcription system was established now allowing the identification of additional factors necessary for the differential gene expression.
Using comparative genomics and high-throughput methods (especially transcriptome- and proteome analyses) we are currently trying - within the frame of the compentence network “Pathogenomics“ located in Würzburg – to develop new approaches to understand the role and the regulation of all genes involved in the infection process of L. monocytogenes and of enteroinvasive E. coli strains.
During the last years our group developed several new approaches for the generation of recombinant life vaccines. In addition to the improvement of a system based on the delivery of heterologous protein antigens via typeI-secretion from attenuated Salmonella strains, our research focused on the development of carriers on the basis of attenuated L. monocytogenes strains. These strains either expose antigens or antigenic epitopes on their surface or deliver antigen-encoding plasmid DNA directly into antigen-presenting cells.
Rewards and prizes:
Prof. Dr. Werner Goebel: Robert-Koch-Preis (1983)
ASM Lecture Award (1984)
Equipment:
Standart equipment for microbiological and cell biological research under S2-conditions is present at the chair of microbiology. The special eqipment includes among others several light microscopes with digital cameras, two microinjection workstations, a real-time PCR machine, a cell sorter, equipment for 2-dimensional gelelectrophoresis and a automatic sequencing machine
Links:
Homepage Microbiology