1. HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, United States
2. Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, United States
3. Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California 92037, United States
4. Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, London NW1 1AT, U.K.
5. St Mary’s Hospital, Department of Infectious Disease, Imperial College London, Section of Virology, Norfolk Place, London W2 1PG, U.K.
6. Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California 92037, United States