1. Institute for Medical Microbiology, Georg-August-University, Kreuzbergring 57, D-37075 Göttingen, Germany
2. Institute for Medical Microbiology, Immunology, and Hygiene, Technische Universität München, Trogerstrasse 30, D-81675 Munich, Germany
3. Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong