1. Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
2. Department of Microbiology and Immunology and Center for AIDS Research, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
3. Department of Pathology, Microbiology and Immunology, University of California, Davis, Davis, California, USA
4. California National Primate Research Center, University of California, Davis, Davis, California, USA
5. Ragon Institute of Massachusetts General Hospital, MIT, and Harvard, Cambridge, Massachusetts, USA