1 Department of Infectious Disease, Shandong Provincial Hospital, Shandong First Medical University, Ji'nan, Shandong, China.
2 Department of Infectious Disease, Shandong Provincial Hospital, Shandong University, Cheeloo College of Medicine, Shandong University, Ji'nan, Shandong, China.
3 Division of Gastroenterology and Hepatology, Stanford University Medical Center, Stanford, CA, USA.