1. Centre for Infectious Disease Control Netherlands; National Institute for Public Health and the Environment (RIVM); Bilthoven; The Netherlands
2. Department of Pathobiology, Faculty of Veterinary Medicine; Utrecht University; Utrecht; The Netherlands
3. Department of Laboratory Medicine, Karolinska Institute; Karolinska University Hospital Huddinge; Stockholm; Sweden
4. Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine; Utrecht University; Utrecht; The Netherlands