1. Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zürich, Zürich, Switzerland
2. University of Helsinki, Medicum, Department of Virology, Helsinki, Finland
3. Servei de Diagnostic en Patologia Veterinaria (SDPV), Departament de Sanitat i Anatomia Animals, Facultat de Veterinària, Universitat Autònoma de Barcelona, Barcelona, Spain