1 Department of Infectious Diseases, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, Jiangsu, China; Institute of Viruses and Infectious Diseases, Nanjing University, Nanjing, Jiangsu, China.
2 Division of Gastroenterology and Hepatology, Veterans Affairs Palo Alto Health Care System, Palo Alto, California; Division of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, California.