1. Department of Microbiology, University of Washington, Seattle, WA, USA.
2. Laboratory of Virology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, MT, USA.
3. Department of Genetics, University of North Carolina, Chapel Hill, NC, USA.
4. Rocky Mountain Veterinary Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, MT, USA.
5. Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC, USA.
6. Washington National Primate Research Center, Seattle, WA, USA.