1. Zoonotic Diseases Laboratory, Livestock and Poultry Sciences Institute, BARC-East, ARS, USDA, Beltsville, MD 20705
2. New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, 382 West Street Road, Kennett Square, PA 19348
3. Wistar Institute of Anatomy and Biology, Philadelphia, PA 19104
4. Pathology Division, US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD 21702