1 aDepartment of Infectious Diseases bShaanxi Provincial Clinical Research Center for Hepatic and Splenic Diseases cNational and Local Joint Engineering Research Center of Biodiagnosis and Biotherapy, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China dDivision of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, California, USA.