1. HIV Immunology and Diagnostic Branch, Division of AIDS, STD, and TB Laboratory Research, National Center for HIV, STD and TB Prevention, Centers for Disease Control and Prevention, Public Health Service, U.S. Department of Health and Human Services, Atlanta, Georgia 30333.
2. Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California 90095.
3. Department of Molecular Biology and Microbiology, Biomolecular Science Center, University of Central Florida, Orlando, Florida 32816-2360.