1. Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
2. School of Life Sciences, Tsinghua University, 100084 Beijing, China.
3. Microbiology, Immunology and Molecular Genetics, School of Medicine and College of Letters and Sciences, University of California, Los Angeles, 277B Biomedical Sciences Research Building, 615 Charles E. Young Drive South, Los Angeles, CA 90095, USA.
4. Molecular Biology Institute, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA.
5. Department of Pathology and Immunology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
6. Peptide Synthesis and Analysis Laboratory, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
7. National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA.