1. College of Life Science and Chemistry, Hunan University of Technology, Zhuzhou, Hunan 412007, P. R. China
2. College of Life Science, Hunan Normal University, Changsha, Hunan 410081, P. R. China
3. State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics and Center for Molecular Imaging and Translational Medicine, School of Public Health, Xiamen University, Xiamen, Fujian 361102, P. R. China