1. Klinische Forschergruppe, OE6711, Medizinische Hochschule Hannover, D-30625 Hannover, Germany
2. Flanders Interuniversity Institute of Biotechnology (VIB6), Laboratory of Microbial Interactions, Department of Molecular and Cellular Interactions, Flanders Interuniversity Institute of Biotechnology and Vrije Universiteit Brussel, B-1050 Brussels, Belgium