1 Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America.
2 Departments of Molecular Genetics and Microbiology (MGM), Pharmacology and Cancer Biology, and Medicine, Duke University Medical Center, Durham, North Carolina, United States of America.
3 Department of Oncology and Diagnostic Sciences, Dental School, University of Maryland, Baltimore, Maryland, United States of America.
4 Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America.
5 Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
6 Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America.
7 Department of Medicine, Division of Infectious Diseases, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America.