1. Department of Pathology, Bacteriology and Poultry Diseases; Faculty of Veterinary Medicine; Ghent University; Merelbeke Belgium
2. Animal Science Department; Biomedical Primate Research Centre; Rijswijk The Netherlands
3. Biometrics Research Group; Faculty of Veterinary Medicine; Ghent University; Merelbeke Belgium
4. Department of Virology; Biomedical Primate Research Centre; Rijswijk The Netherlands
5. Department of Morphology; Faculty of Veterinary Medicine; Ghent University; Merelbeke Belgium