1. Department of Biochemistry; University of Washington; Seattle Washington 98195
2. IAVI Neutralizing Antibody Center, The Scripps Research Institute; La Jolla California 92037
3. Department of Immunology and Microbial Science; The Scripps Research Institute; La Jolla California 92037
4. Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute; La Jolla California 92037
5. Ragon Institute of MGH, MIT and Harvard; Cambridge Massachusetts