1. Division of Immunology, New England Primate Research Center, Harvard Medical School, Southborough, MA 01772.
2. VIRxSYS, Gaithersburg, MD 20877.
3. Present address: Department of Standards Development, U.S. Pharmacopeia, Rockville, MD 20852.
4. Sydney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD 21231.
5. Present address: Lentigen Corporation, Baltimore, MD 21227.
6. Partners AIDS Research Unit and Infectious Disease Unit, Massachusetts General Hospital, Boston, MA 02115.