1. Laboratorie of Molecular Pathobiology, Department of Pharmacology and Pathobiology, The Royal Veterinary and Agricultural University, DK-1870 Frederiksberg C. Denmark
2. Laboratorie of Veterinary Pathology, Department of Pharmacology and Pathobiology, The Royal Veterinary and Agricultural University, DK-1870 Frederiksberg C. Denmark
3. Laboratory of Virology and Immunology, Department of Veterinary Microbiology, The Royal Veterinary and Agricultural University, DK-1870 Frederiksberg C. Denmark
4. Danish Fur Breeders Association, Glostrup, Denmark
5. Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, MT