1. Department of Microbiology and Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
2. State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
3. Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
4. Miyun District Center for Disease Control and Prevention, Beijing, China
5. Beijing Center for Disease Prevention and Control, Beijing, China
6. Department of Gastroenterology, Peking University Third Hospital, Beijing, China