1. Seattle Biomedical Research Institute, Seattle, Washington 98109; and Regional Primate Research Center, University of Washington, Seattle, Washington 98195
2. Seattle Biomedical Research Institute, Seattle, Washington 98109
3. Department of Medicine, University of Washington, Seattle, Washington 98195
4. Duke University Medical Center, Durham, North Carolina 27710
5. Regional Primate Research Center, University of Washington, Seattle, Washington 98195
6. Department of Biostatistics, University of Washington, Seattle, Washington 98195
7. Department of Pathology, University of California, Davis, California 95616
8. Laboratory of Viral Carcinogenesis, National Cancer Institute, Frederick, Maryland 21702
9. Seattle Biomedical Research Institute, Seattle, Washington 98109; and Department of Pathobiology, University of Washington, Seattle, Washington 98195