1. Department of Microbiology, University of Iowa, Iowa City, Iowa, USA
2. University of Chicago, Department of Biochemistry and Molecular Biology, Chicago, Ilinois, USA
3. The Forsyth Institute, Department of Microbiology, Cambridge, Massachusetts, USA
4. Division of Select Agents and Toxins, Office of Public Health Preparedness and Response, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
5. Harvard Medical School, Department of Microbiology and Immunobiology, Boston, Massachusetts, USA