1. Comprehensive AIDS Research Center, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, School of Medicine, Tsinghua University, Beijing 100084, China.
2. Ministry of Education Key Laboratory of Protein Science, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
3. School of Life Sciences, Tsinghua University, Beijing 100084, China.
4. Department of Microbiology, The University of Hong Kong, Hong Kong, China.
5. Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu 610041, China.