1. Department of Medicine, Division of Infectious Diseases, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
2. Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, USA
3. Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA
4. Department of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham School of Medicine, Birmingham, Alabama, USA