1. A. Moghaddam, B. Annis, F. Wang, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA.
2. M. Rosenzweig, Division of Immunology, New England Regional Primate Research Center, Harvard Medical School, 1 Pine Hill Drive, Southborough, MA 01172, USA.
3. D. Lee-Parritz, Division of Primate Resources, New England Regional Primate Research Center, Harvard Medical School, 1 Pine Hill Drive, Southborough, MA 01172, USA.
4. R. P. Johnson, Division of Immunology, New England Regional Primate Research Center, Harvard Medical School, 1 Pine Hill Drive, Southborough, MA 01172, USA, and AIDS Research Center and Infectious Disease Unit, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA.