梅毒螺旋体 Tp0751蛋白在早期梅毒兔模型皮损转录水平的研究

Transcript levels of the Treponema pallidum protein Tp0751 in skin lesions of a rabbit model of early syphilis

目的：探讨梅毒螺旋体（Tp）Tp0751蛋白在早期梅毒兔模型中转录水平变化情况。方法3只新西兰白兔背部剔毛，皮下注入107/ml Tp Nichols Seattle 株0.1 ml，共10处，建立早期兔梅毒感染模型。同时于未注射部位行皮肤活检术，切取0.4 cm ×0.4 cm 皮肤作为阴性对照。每天观察注射部位皮肤变化情况，测量并记录皮疹大小。每隔3天切取1处注射部位0.4 cm ×0.4 cm 皮肤用于 Tp0751和 Tp0574 mRNA 检测。整个实验过程30 d，共行11次皮肤活检。荧光定量 PCR 连续动态观察兔硬下疳皮损形成过程中 Tp0751 mRNA 表达的差异。结果新西兰白兔皮下注入 Tp 后，背部在第6天出现红色丘疹，到第19天皮疹达最大并出现溃疡，形成硬下疳。第25天，全身陆续出现播散性二期梅毒疹。Tp0574和 Tp0751 mRNA 水平在早期呈现上升趋势，到第15天达最高峰（与其他各时间点比较，均 P ＜0.05），其后迅速下降，在第27天有少许上升。标准化的 Tp0751 mRNA 从第15天起转录水平逐渐升高，到第24天达最高峰（P ＜0.05）。结论标准化 Tp0751转录水平在 Tp 被清除后期出现全身播散性二期梅毒疹前高表达。表明 Tp0751蛋白可能参与 Tp 全身播散。

Objective To trace changes in the transcript level of the Treponema pallidum（Tp）protein Tp0751 in skin lesions of a rabbit model of early syphilis. Methods Three New Zealand white rabbits were intracutaneously injected with 0.1 ml of Tp （Nichols Seattle strains）suspensions （107 treponemes/ml）at 10 sites on the shaved back to establish a model of early syphilis. All the rabbits received a single injection with the total amount of treponemes being 107. Then, skin changes at injection sites were observed, and the size of skin rashes was recorded on a daily basis. Skin specimens sized 0.4 cm × 0.4 cm were excised from an injection site and a non-injection site（negative control）separately every 3 days for the detection of Tp0751 and Tp0574 mRNAs. The whole experiment lasted 30 days, and a total of 11 skin biopsies were carried out. Fluorescence-based quantitative PCR was performed to measure the mRNA expressions of Tp0751 and Tp0574 continuously and dynamically during the development of chancre. Results After intracutaneous injection of Tp suspensions, red papules occurred on the back of rabbits on day 6, and reached maximum size on day 19 with the formation of ulcer and chancre. On day 25, disseminated secondary syphilides gradually appeared all over the body surface of the rabbits. The mRNA expression levels of Tp0574 and Tp0751 increased at the early stage, peaked onday 15 （compared with the other time points, all P ＆lt; 0.05）, thereafter rapidly declined, but rose slightly on day 27. The standardized expression level of Tp0751 mRNA increased gradually after day 15, and peaked on day 24 （compared with the other time points, all P ＆lt; 0.05）. Conclusion The transcript level of Tp0751 was high in rabbits at the late stage of Tp clearance when generalized disseminated secondary syphilides had not appeared, suggesting that Tp0751 may be involved in the systemic spread of Tp.