1. Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
2. Intracellular Pathogens Research Laboratory, Comparative Medicine Institute, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
3. Bureau of Laboratories, Division of Infectious Disease, Michigan Department of Health and Human Services, Lansing, Michigan, USA
4. Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA
5. Department of Population Health & Reproduction, School of Veterinary Medicine, University of California, Davis, California, USA