1. 1 From the Department of Virology, Max Planck Institute for Biochemistry, Martinsried, Germany; the Institute of Molecular Virology, GSF-National Research Center for Environment and Health, Neuherberg, Germany; the Policlinic of the Ludwig Maximilians University, Munich, Germany; the Department of Dermatology, University of Vienna, Medical School, Vienna, Austria; the Laboratory of Virology, Istituto Superiore di Sanità, Rome, Italy; and the Bavarian Nordic Research Institute/AS, Martinsried, Germany.