1. Department of Medicine, Division of Infectious Disease, Duke University Medical Center, Durham, NC 27710, USA
2. Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
3. Department of Infectious Diseases, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
4. Duke Clinical Research Institute, Durham, NC 27710, USA