1. Animal Population Health Institute, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523
2. USDA, ARS, NAA Plum Island Animal Disease Center, Greenport, NY 11944—0848
3. Department of Microbiology, AIDL-Foothills Campus, Colorado State University, Fort Collins, CO 80523
4. Centers of Epidemiology and Animal Health of USDA:APHIS:VS, 2150 Centre Avenue, Building B, Fort Collins, CO 80526—8117