Guiwen Guan1, Jun Zou1, Ting Zhang1, Fengmin Lu2, Xiangmei Chen3. 1. Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China. 2. Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; Hepatology Institute, Peking University People's Hospital, Beijing 100044, China. Electronic address: lu.fengmin@hsc.pku.edu.cn. 3. Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China. Electronic address: xm_chen6176@bjmu.edu.cn.