1. State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, China CDC, Beijing 102206, China
2. School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney NSW 2052, Australia
3. Branch for Enteric Disease Control and Prevention, Institute for Infectious Disease Control and Prevention, Henan Center for Disease Control and Prevention, Zhengzhou 450016, China
4. Gansu Center for Disease Control and Prevention, Lanzhou 730000, China