1. Departments of Chemistry and Medicinal Chemistry, Purdue University, West Lafayette, Indiana 47907
2. Department of Biology, Molecular Basis of Disease Program, Georgia State University, Atlanta, Georgia 30303
3. Departments of Hematology and Infectious Diseases, Kumamoto University School of Medicine, Kumamoto 860-8556, Japan
4. Experimental Retrovirology Section, HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, Maryland 20892