1. Department of Epidemiology and Microbiology, Huadong Medical Institute of Biotechniques, Nanjing, Jiangsu 210002, P.R. China
2. Department of Obstetrics and Gynecology, Nanjing Maternity and Child Health Care Hospital, Obstetrics and Gynecology Hospital Affiliated to Nanjing Medical University, Nanjing, Jiangsu 210004, P.R. China
3. Department of Infectious Disease, Anhui Medical University Affiliated with Bayi Clinical College, Hefei, Anhui 230000, P.R. China
4. Institute of Liver Disease, Nanjing Jingdu Hospital, Nanjing, Jiangsu 210002, P.R. China