1. Liver Disease Center, Qinhuangdao Third Hospital, Qinhuangdao, Hebei 066000, P.R. China
2. Department of Obstetrics, Qinhuangdao Women's and Children's Hospital, Qinhuangdao, Hebei 066000, P.R. China
3. Department of Infectious Diseases, Peking University First Hospital, Beijing 100034, P.R. China
4. Department of Microbiology and Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, P.R. China