1. Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 021111;
2. Department of Microbiology and Immunology, Duke University, Durham, North Carolina 277102;
3. Unité des Agents Antibactériens, Institut Pasteur, Paris Cedex 15, France3;
4. Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany4;
5. Department of Pathobiology, University of Washington, Seattle, Washington 981955;
6. Department of Microbiology, Monash University, Clayton, Australia6; and
7. Departments of Biological Sciences and of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada7