1. Department of Pathobiology and Division of Comparative Medicine, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32610-0880, USA
2. Senior authors with equal contributions to the manuscript
3. U.S. Geological Survey, Biological Resources Division, Riverside, California 92507, USA
4. Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida 32610, USA
5. Laboratory of Structural Biology and Molecular Medicine, University of California at Los Angeles, Los Angeles, California 90024, USA
6. Department of Pathology, Microbiology, and Immunology, University of California at Davis, Davis, California 95616, USA