1. U.S. Department of Agriculture, Agricultural Research Service, Animal Disease Research Unit, Washington State University, Pullman, Washington 99164-6630
2. Washington State University, Department of Veterinary Microbiology and Pathology, Pullman, Washington 99164-7040
3. Center for Integrated Biotechnology, Washington State University, Pullman, Washington 99164
4. U.S. Department of Agriculture, Agricultural Research Service, U.S. Sheep Experiment Station, Dubois, Idaho 83423
5. Centers for Epidemiology and Animal Health, Animal and Plant Health Inspection Service, U.S. Department of Agriculture, Fort Collins, Colorado 80526