1. Chinese Center for Disease Control and Prevention, Beijing, PR China
2. Key Laboratory of Immunology of AIDS, Ministry of Health, First Affiliated Hospital, China Medical University, Shenyang, PR China
3. Kaiyuan Center for Disease Control and Prevention, Yunnan, PR China
4. National Center for AIDS/STD Prevention and Control, Chinese Center for Disease Control and Prevention, Beijing, PR China
5. Peking University Clinical Research Institute, Beijing, PR China