1. Institute of Microbiology, ETH Zürich, 8092 Zürich, Switzerland
2. Max von Pettenkofer-Institut, Ludwig Maximilians Universität, 80336 Munich
3. GSF-Research Center for Environment and Health, 85764 Neuherberg
4. Institute of Medical Microbiology, Immunology, and Hygiene
5. GBF, 38124 Braunschweig, Germany
6. Institute of Pathology, Technical University of Munich, 81675 Munich