1. United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Bacterial Diseases of Livestock Unit, P.O. Box 70, Ames, Iowa 50010-0070, USA
2. United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Respiratory Diseases of Livestock Unit, P.O. Box 70, Ames, Iowa 50010-0070, USA
3. Immunobiology Graduate Program, Iowa State University, Ames, Iowa 50011, USA
4. Wyoming Game and Fish Department, 2362 Highway 34, Wheatland, Wyoming 82201, USA