1. Department of Virology, Immunology and Parasitology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
2. Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
3. Department of Morphology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
4. Institut fur Virologie, Zentrum fur Infektionsmedezin, Freie Universitat Berlin, Berlin, Germany