1. Division of Vaccine Research, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215
2. Ragon Institute of MGH, MIT and Harvard, Boston, Massachusetts 02214
3. Duke University Medical Center, Durham, North Carolina 27710
4. University of California, Irvine School of Medicine, Irvine, California 92697
5. Department of Biostatistics, University of Washington, Seattle, Washington 98109
6. New England Primate Research Center, Southborough, MA 01772
7. Crucell Holland BV, 2301 CA, Leiden, The Netherlands