1. Department of Immunology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong 250012, P.R. China
2. Department of Gynecology and Obstetrics, Jinan Central Hospital Affiliated to Shandong University, Jinan, Shandong 250013, P.R. China
3. Department of Microbiology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong 250012, P.R. China