1. Virus-Cell Interaction Section, HIV Drug Resistance Program, Center for Cancer Research, National Cancer Institute, Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
2. Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland, USA
3. AIDS Research Center, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan
4. Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA