1. Department of Clinical Sciences, Colorado State University, Fort Collins, CO 80523, USA
2. Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
3. Swine Veterinary Center, St. Peter, MN 56082, USA
4. Department of Veterinary Population Medicine, Veterinary Diagnostic Laboratory and Swine Disease Eradication Center, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55455, USA
5. Idaho State University, Pocatello, ID 83209, USA
6. College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA