1 Division of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, CA.
2 Department of Infectious Disease, the Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.
3 Shaanxi Provincial Clinical Research Center for Hepatic & Splenic Diseases, the Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.
4 National & Local Joint Engineering Research Center of Biodiagnosis and Biotherapy, the Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.