1. National Institute of Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
2. School of Public Health, Harbin Medical University, Harbin, China.
3. Yunnan Provincial Center for Disease Control and Prevention, Kunming, China.
4. Department of Pathology, Center for Biodefence and Emerging Infectious Diseases, Seally Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas.