1. Department of Infectious Diseases and Pathobiology, University of Bern, Bern, Switzerland
2. Institute of Virology and Immunology IVI, Mittelhäusern, Switzerland
3. Institute of Food Safety and Hygiene, National Reference Centre for Poultry and Rabbit Diseases, Vetsuisse Faculty, University of Zürich, Zürich, Switzerland
4. Institute of Diagnostic Virology, Friedrich Loeffler-Institut, Greifswald, Germany