About the Authors
Department of Molecular Microbiology and Immunology and Graduate Program in Pathobiology, Division of Biology and Medicine, Brown University, Providence, Rhode Island, United States of America
The authors have declared that no competing interests exist.
Conceived and designed the experiments: JDW MST LB. Performed the experiments: JDW MST DC LB. Analyzed the data: JDW MST DC LB. Wrote the paper: JDW MST LB.