Abstract: Zheng Bingjie, Yin Yueping, Han Yan, Shi Meiqin, Xiang Zhi, Yu Ruixing. Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical Collage; Reference Laboratory, National Center for Sexually Transmitted Disease Control, China Center for Disease Control and Prevention, Nanjing 210042, China Corresponding author: Yin Yueping, Email: yinyp@ncstdlc.org 【Abstract】 Objective To compare the pathogenicity between Ureaplasma urealyticum serotype 1 （Up1） and 8 （Uu8） in the genital tract of BALB/c mice. Methods A total of 48 BALB/c mice were randomly and equally divided into four groups: blank control group receiving no treatment, estradiol group pretreated with intramuscular injection of estradiol followed by intravaginal inoculation with sterial liquid culture media, Up1 and Uu8 groups pretreated with intramuscular injection of estradiol followed by intravaginal inoculation with suspensions of Up1 and Uu8 respectively. Three mice were randomly selected from each group to be sacrificed after the collection of vaginal lavage fluid on day 3, 7, 14 and 21 after the inoculation. Vaginal and uterine tissue specimens were obtained from these sacrificed mice and underwent hematoxylin and eosin （HE） staining. Vaginal lavage fluid samples were subjected to culture of Uu and measurement of tumor necrosis factor-α（TNF-α）. Results No evidences were observed for Uu growth in either the blank control group or estradiol group at any of the time points after the inoculation, with the average level of TNF-α in vaginal lavage fluid being （4.17 ± 0.85） pg/ml at these time points in both groups. Uu grew in all the vaginal lavage fluid samples from the Up1 and Uu8 groups at the four time points, with the color change unit （CCU） value decreasing with time. The level of TNF-α in vaginal lavage fluid peaked on day 14 after the inoculation in the Up1 （（14.93 ± 1.11） pg/ml） and Uu8 （（27.04 ± 24.26） pg/ml） groups. Both Up1 and Uu8 infection caused acute and chronic inflammatory responses in the mice, which were mainly located in the uterus, and Up1 might cause intrauterine adhesion. Conclusions At the same inoculation concentration, no significant difference is found in the pathogenicity between Up1 and Uu8, both of which appear to mainly cause cervicitis. Up1 might be partially responsible for intrauterine adhesion in mice.

Key words: Ureaplasma urealyticum, Mice，inbred BALB/c, Virulence