1. Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
2. Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
3. Howard Hughes Medical Institute, Baltimore, Maryland
4. Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland
5. Division of Intramural Research, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, Maryland
6. University of North Carolina, Chapel Hill, North Carolina