1. Department of Molecular Microbiology, Washington University School of Medicine , St. Louis, Missouri, USA
2. Department of Microbiology, University of Chicago , Chicago, Illinois, USA
3. Meakins-Christie Laboratories, Department of Medicine, McGill University , Montreal, Quebec, Canada
4. Meakins-Christie Laboratories, Department of Microbiology and Immunology, McGill University , Montreal, Quebec, Canada
5. Meakins-Christie Laboratories, Department of Pathology, McGill University , Montreal, Quebec, Canada
6. Department of Theoretical Physics, University of Zaragoza, Institute for Biocomputation and Physics of Complex Systems (BIFI) , Zaragoza, Spain
7. Department of Medicine, Genetic Section, University of Chicago , Chicago, Illinois, USA