1. Division of Infectious Diseases and International Health, Department of Medicine, Duke University Medical Center, Durham, North Carolina
2. Human Vaccine Institute, Department of Medicine, Duke University Medical Center, Durham, North Carolina
3. Division of Infectious Diseases and International Health, Department of Medicine, Department of Pathology, Duke University Medical Center, Durham, North Carolina
4. Human Vaccine Institute, Department of Medicine, Duke University Medical Center, Durham, North Carolina, and Infectious Diseases Section, Veterans Affairs Medical Center, Durham, North Carolina