1. Molecular Immunogenetics and Vaccine Research Section, Metabolism Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
2. Laboratory of Viral Disease, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892.
3. Repligen Corporation, Cambridge, MA 02139.
4. Torrey Pines Institute for Molecular Studies, San Diego, CA 92121.
5. Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892.