1. Institute for Medical Virology and Epidemiology of Viral Diseases, University Hospital Tübingen, Tübingen, Germany
2. Institute of Applied Physics, Eberhard-Karls-University, Tübingen, Germany
3. Quantitative Biology Center, Eberhard-Karls-University, Tübingen, Germany
4. Institute for Virology, Hannover Medical School, Hannover, Germany