About the Authors
Tufts University School of Medicine, Boston, Massachusetts, United States of America
Division of Infectious Diseases, Center for Infectious Disease Research, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
The authors have declared that no competing interests exist.
Conceived and designed the experiments: JC. Performed the experiments: DGML MF. Analyzed the data: DGML MF JC. Wrote the paper: DGML JC.