1. Department of Microbiology, Third Military Medical University, Chongqing 400038, China
2. Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing 400038, China
3. Department of Medical Laboratory, Chengdu Military General Hospital, Chengdu 610083, China
4. The Forsyth Institute, 245 First St, Cambridge, MA 02142, USA
5. School of Dentistry, University of California, Los Angeles, CA 90095, USA