1. Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan
2. Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
3. EMBL-European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
4. Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia