1. Institute of Virology, Justus Liebig University Giessen, Germany
2. Institute of Virology and Immunology (IVI), Bern and Mittelhäusern, Switzerland
3. Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Switzerland
4. Institute of Animal Pathology, Vetsuisse-Faculty, University of Bern, Switzerland
5. Institute of Medical Virology, University of Zürich, Switzerland
6. COMPATH, University of Bern, Switzerland