1. Division of Viral Transformation Mechanisms, Research Program “Infection, Inflammation and Cancer”, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 242, 69120 Heidelberg, Germany
2. Institute of Virology, Medical Faculty and University Hospital Cologne, University of Cologne, Fürst-Pückler-Str. 56, 50935 Cologne, Germany