1. Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
2. Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
3. Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, SK, S7N 5E3, Canada
4. Department of Virology, Veterinary and Agrochemical Research Centre (VAR-CODA CERVA), Groeselenberg 99, B-1180 Brussels, Belgium