1. Department of Epidemiology, Fourth Military Medical University, 169 Changle West Road, Xi’an 710032, PR China
2. Department of Hepatobiliary Surgery, Xijing Hospital, 169 Changle West Road, Xi’an 710032, PR China
3. Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 W. Queen Lane, Philadelphia, PA 19129, USA
4. Hepatitis B Foundation, 3805 Old Easton Road, Doylestown, PA 18902, USA