1. Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
2. Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
3. Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
4. Department of Virology, Medicum, Faculty of Medicine, University of Helsinki, Helsinki, Finland