1. The Jackson Laboratory, Bar Harbor, ME
2. Laboratory of Virology, Rega Institute for Medical Research, University of Leuven, Leuven, Belgium
3. Department of Pathology, National Zoological Park, Washington, DC
4. Department of Pathobiology, The University of Florida, College of Veterinary Medicine, Gainesville, FL
5. Cornell University, College of Veterinary Medicine, Ithaca, NY
6. Louisiana Veterinary Medical Diagnostic Laboratory, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA
7. Department of Pathobiology, Texas A&M University, School of Veterinary Medicine, College Park, TX
8. Faculté de Médecine Vétérinaire, Université de Montréal, Saint Hyacinthe, Québec, Canada
9. Department of Pathology, Georgetown University, School of Medicine, Washington, DC