1. Rush Medical College, Chicago, Illinois 606121;
2. University of Southern California, Los Angeles, California 900332;
3. Westat, Rockville, Maryland 208503;
4. New England Research Institutes, Watertown, Massachusetts 024724;
5. Organon Teknika Corporation, Durham, North Carolina 277125;
6. Department of Infectious Diseases, Roche Molecular Systems, Inc., Alameda, California 945016; and
7. National Institute of Child Health and Human Development, Bethesda, Maryland 208927