About the Authors
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
The authors have declared that no competing interests exist.
APL, XL, JH, and TGM conceived and designed the experiments. APL, XL, and IT performed the experiments. APL analyzed the data. TGM contributed reagents/materials/analysis tools. APL and TGM wrote the paper.