1. Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA
2. Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, Massachusetts, USA
3. Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
4. Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
5. Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA