WHO Collaborating Center for Standardization and Evaluation of Biologicals, WHO Collaborating Center for Standardization and Evaluation of Biologicals, WHO Collaborating Center for Standardization and Evaluation of Biologicals, WHO Collaborating Center for Standardization and Evaluation of Biologicals, National Institutes for Food and Drug Control (NIFDC) - Division of HIV/AIDS and Sex-transmitted Virus Vaccines, National Institutes for Food and Drug Control (NIFDC) - Division of HIV/AIDS and Sex-transmitted Virus Vaccines, National Institutes for Food and Drug Control (NIFDC) - Division of HIV/AIDS and Sex-transmitted Virus Vaccines, National Institutes for Food and Drug Control (NIFDC) - Division of HIV/AIDS and Sex-transmitted Virus Vaccines, WHO Collaborating Center for Standardization and Evaluation of Biologicals, National Institutes for Food and Drug Control (NIFDC) - Division of HIV/AIDS and Sex-transmitted Virus Vaccines, WHO Collaborating Center for Standardization and Evaluation of Biologicals, WHO Collaborating Center for Standardization and Evaluation of Biologicals, WHO Collaborating Center for Standardization and Evaluation of Biologicals, WHO Collaborating Center for Standardization and Evaluation of Biologicals, WHO Collaborating Center for Standardization and Evaluation of Biologicals, WHO Collaborating Center for Standardization and Evaluation of Biologicals, WHO Collaborating Center for Standardization and Evaluation of Biologicals, WHO Collaborating Center for Standardization and Evaluation of Biologicals, National Institutes for Food and Drug Control (NIFDC) - Division of HIV/AIDS and Sex-transmitted Virus Vaccines, Chinese Academy of Sciences (CAS) - CAS Key Laboratory of Pathogenic Microbiology and Immunology, Beijing Biocytogen Co., Ltd., Sino Biological Inc. - Beijing Antibody Research Key Laboratory, Tsinghua University - Center for Global Health and Infectious Diseases, University of South China - Translational Medicine Institute, Chinese Center for Disease Control and Prevention (China CDC) - National Institute for Viral Disease Control and Prevention, Government of the People's Republic of China - Division of HIV/AIDS and Sex-transmitted Virus Vaccines and WHO Collaborating Center for Standardization and Evaluation of Biologicals