About the Authors
Laboratory of Analytical Microbiology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
The authors have declared that no competing interests exist.
Conceived and designed the experiments: JZ RY. Performed the experiments: SQ QS LZ ZG DZ. Analyzed the data: SQ RY. Wrote the paper: SQ RY.