Abstract
1Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
2, and Department of Medical Microbiology, School of Medicine, University of California, Davis, CA 95616, USA
3Department of Microbiology, The Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
4Natural Sciences Division, Pacific Lutheran University, Tacoma, WA 98447, USA