1. Division of Viral Pathogenesis, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
2. New England Regional Primate Research Center, Harvard Medical School, Southborough, MA 01772, USA.
3. Bernhard-Nocht-Institute for Tropical Medicine, 20359 Hamburg, Germany.
4. Centocor, Malvern, PA 19355, USA.
5. Beckman Coulter, Miami, FL 33196, USA.
6. Department of Surgery, Duke University Medical Center, Durham, NC 27710, USA.
7. Institute of Immunology, Technical University of Dresden, 01101 Dresden, Germany.