1. Institute of Virology, University of Bonn, Sigmund-Freud-Straße 25, D-53105 Bonn, Germany
2. Department of Surgery, University of Bonn, Sigmund-Freud-Straße 25, D-53105 Bonn, Germany
3. Institute of Pathology, University of Bonn, Sigmund-Freud-Straße 25, D-53105 Bonn, Germany
4. Paul-Ehrlich-Institut, Paul-Ehrlich-Straße 51-59, D-63225 Langen, Germany