1. Division of Molecular and Experimental Surgery, Department of Surgery, University of Erlangen-Nuremberg, 91054 Erlangen, Germany.
2. University of Veterinary Medicine, Research Institute of Virology and Biomedicine, A-1210 Vienna, Austria.
3. Austrianova Biotechnology GmbH, A-1210 Vienna, Austria.
4. Department of Virus Research, Max-Planck-Institute of Biochemistry, Martinsried, Germany.