1. Department of Infectious Diseases the Second Affiliated Hospital of Xi'an Jiaotong University Xi'an China
2. National and Local Joint Engineering Research Center of Biodiagnosis and Biotherapy the Second Affiliated Hospital of Xi'an Jiaotong University Xi'an China
3. Division of Gastroenterology and Hepatology Stanford University Medical Center Palo Alto California USA
4. Department of Epidemiology and Population Health Stanford University Palo Alto California USA