About the Authors

David L Alexander

Affiliation Department of Microbiology and Immunology, Stanford University, Stanford, California, United States of America

Jeffrey Mital

Affiliation Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, United States of America

Gary E Ward

Affiliation Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, United States of America

Peter Bradley

Affiliations Department of Microbiology and Immunology, Stanford University, Stanford, California, United States of America , Department of Microbiology and Immunology, University of California, Los Angeles, Los Angeles, California, United States of America

John C Boothroyd

To whom correspondence should be addressed. E-mail: jboothr@stanford.edu

Affiliation Department of Microbiology and Immunology, Stanford University, Stanford, California, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

DLA conceived, designed, and performed the experiments. DLA, JM, PB, and JCB analyzed the data. JM, GEW, and PB contributed reagents/materials/analysis tools. DLA and JCB wrote the paper.