1. CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology; Chinese Academy of Sciences (CAS), Chaoyang District; Beijing 100101 P. R. China
2. National Glycoengineering Research Center; Shandong University; Jinan 250012 P. R. China
3. CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology; Chinese Academy of Sciences (CAS), Chaoyang District; Beijing 100101 P. R. China
4. School of Materials Science and Engineering; Changchun University of Science and Technology, Weixing Road; Changchun 130022 P. R. China
5. School of Physical and Mathematical Sciences; Nanyang Technological University; Singapore 637371 Singapore
6. Savaid Medical School; University of Chinese Academy of Sciences, Huairou District; Beijing 101408 P. R. China
7. Center for Influenza Research and Early Warning (CASCIRE); Chinese Academy of Sciences, Chaoyang District; Beijing 100101 P. R. China