1. Institute for Medical Microbiology, University Medical Center Göttingen, Kreuzbergring 57, 37075 Göttingen, Germany
2. Federal Institute for Occupational Safety and Health (BAuA), Biological Agents, Nöldnerstraße 40-42, 10317 Berlin, Germany
3. Institute for Occupational, Social and Evironmental Medicine, University Medical Center Göttingen, Waldweg 37b, 37073 Göttingen, Germany