国家传染病科技重大专项课题2008 ZX10002011,2012 ZX10004503;科技部国际合作与交流专项2011 DFA31030;华中科技大学研究生创新创业基金No.HF-11-30-2013This work was supported by grants from the National Major Science and Technology Special Project for Infectious Diseases of China2008 ZX10002011,2012 ZX10004503;the International Science & Technology Cooperation Program of China No.2011