1. Institute of Virology, Technische Universität München/Helmholtz Zentrum München, Trogerstrasse 30, D-81675 München, Germany
2. Department of Epidemiology, Helmholtz Centre for Infection Research, D-38124 Braunschweig, Germany; Hannover Medical School, D-30625 Hannover, Germany
3. German Center for Infection Research (DZIF), Munich Partner Site