1. Federal Research Centre for Virus Diseases of Animals (BFAV), Jena
2. Institute of Medical Microbiology and Hygiene, University of Regensburg, Regensburg
3. Bavarian State Office for Health and Food Safety, Oberschleissheim
4. Institute of Medical Microbiology, University of Leipzig, Leipzig
5. Germany; Veterinary Research Institute, Brno, Czech Republic
6. Central Veterinary Institute, Budapest, Hungary
7. Croatian Veterinary Institute, Zagreb, Croatia
8. University Clinic of Respiratory and Allergic Diseases, Golnik, Slovenia