梅毒螺旋体HtrA在感染中的侵袭机制研究

梅毒螺旋体（Treponema pallidum，Tp）是严重危害人类健康的性传播疾病梅毒的病原体。Tp侵袭力强大，是其突破各类屏障引起全身感染的关键因素，但分子机制尚不明确。高温需求蛋白A（HtrA）在多种病原体介导感染侵袭中可发挥重要作用，前期研究发现TpHtrA可体外裂解细胞连接因子E-cadherin。本研究拟在此基础上以银染SDS-PAGE和Western Blot检测TpHtrA对细胞连接因子和细胞外基质蛋白的水解作用，以基因突变技术确定TpHtrA蛋白酶活性位点，以Transwell和激光共聚焦等观察TpHtrA对人黏膜上皮细胞和血管内皮细胞的损伤，以伯氏疏螺旋体异源表达TpHtrA，免疫电镜分析其亚细胞定位、qRT-PCR检测其在C57BL/6小鼠体内的播散，从分子、细胞及动物不同层面探索TpHtrA在Tp感染中的侵袭作用，为Tp致病机制、治疗及疫苗研发提供新思路。

Syphilis is a multistage sexually transmitted disease caused by Treponema pallidum, subspecies pallidum (T. pallidum), and the pathogenesis remains unclear. It is probable that invasion is the key factor for Treponema pallidum to break through various barriers and cause systemic infection. HtrA can play an important role in promoting pathogen invasion. Previous studies have shown that TpHtrA can cleave the adherens junction protein E-cadherin. In this work, we will firstly determine the hydrolysis and protease active sites of TpHtrA by using silver stained SDS- PAGE, Western Blot, and gene mutation technology. Then immunoelectron microscopy, Transwell, and other methods were used for expolring the damage to human mucosal epithelial cells and vascular endothelial cells. Borrelia burgdorferi was used for heterologous expression of TpHtrA. The subcellular localization of TpHtrA was analysed by immunoelectron microscopy and the invasion of TpHtrA in C57BL/6 mice was determined by quantitative reverse transcription PCR (qRT-PCR). All the strategies help to explore the invasion of TpHtrA in T. pallidum infection at the molecular, cellular and animal levels, which will provide a novel insight and evidence for the pathogenesis, prevention and vaccine development of T. pallidum infection.