1. Center for Public Health and Infectious Disease, Institutes of Biomedical Sciences, Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, China
2. Key Laboratory of Medical Molecular Virology of MoH & MoE, Shanghai Medical College, Fudan University, Shanghai 200032, China
3. International Vaccine Institute, Seoul 151-818, Republic of Korea
4. Laboratory of Medical Molecular Biology, Shanghai Medical College, Fudan University, Shanghai 200032, China
5. Department of Biostatistics, School of Public Health, Fudan University, Shanghai 200032, China