梅毒螺旋体感染家兔的扩散趋势及感染依赖性抗原Tp0971的免疫保护作用研究

Study on the spreading tendency of Treponema pallidum infection in rabbits and the immunoprotective effect of infection-dependent antigen Tp0971

目的探讨梅毒螺旋体(Tp)感染家兔后的扩散趋势及感染依赖性抗原Tp0971的免疫保护作用。方法构建Tp感染家兔模型,连续进行监测并采用定量PCR法检测Tp载量,分析Tp感染家兔后的扩散趋势。用诱导、纯化的Tp0971重组蛋白联合CpG ODNs佐剂免疫家兔(Tp0971组),并设CpG佐剂(对照组)和PBS(空白组)对照。Tp0971组末次免疫2周后接种Tp悬液,记录1个月内3组家兔硬结、溃疡发生情况,定量PCR法检测比较Tp载量,Western blot检测接种皮肤组织炎症细胞因子NLRP3、IL-1β水平。结果Tp感染家兔后皮肤组织出现硬下结和溃疡,Tp载量表达水平表现为降低、升高、再降低、再升高的变化特点。Tp0971组硬结发生时间、硬结最大直径、溃疡发生时间、溃疡发生率及炎症因子NLRP3、IL-1β水平均显著低于对照组和空白组(均P<0.05);Tp0971免疫后家兔组织器官中Tp载量表达受到一定抑制,当接种后14 d时,Tp0971组Tp载量下降、且显著低于对照组和空白组(均P<0.05)。结论家兔感染Tp后表现出和人类梅毒相似的临床症状,且在整个感染过程中各器官组织的Tp载量呈降低、升高的循环反复动态变化;Tp0971免疫对Tp感染家兔临床症状的改善和Tp载量的抑制有一定作用,但不能完全清除宿主体内的Tp。

Objective To investigate the spreading tendency of Treponema pallidum(Tp)after infection of rabbits and the immunoprotective effect of the infection-dependent antigen Tp0971.Methods A Tp-infected rabbit model was constructed,and continuous monitoring was performed.The Tp load was measured by quantitative PCR and the spreading trend of Tp infection in rabbits was analyzed.Rabbits(Tp0971 group)were immunized with induced and purified Tp0971 recombinant protein combined with CpG ODNs adjuvant,and CpG adjuvant and PBS were set up as the control group and the blank group,respectively.Tp0971 group was inoculated with Tp suspension 2 weeks after the last immunization,and the occurrence of induration and ulcers in the three groups of rabbits was recorded within 1 month.The quantitative PCR method was used to detect the Tp load,and Western blot was used to detect the levels of inflammatory cytokines NLRP3 and IL-1βin the inoculated skin tissue.Results Tp-infected rabbits developed induration and ulcers in the skin tissue,and Tp load expression levels showed a variable pattern of decreasing,increasing,then decreasing and increasing again.The time of induration,the maximum diameter of induration,the time of ulcer,the incidence of ulcer and the levels of inflammatory factors NLRP3 and IL-1βin the Tp0971 group were significantly lower than those in the control and the blank group(P<0.05);After Tp0971 immunization,the expression of Tp load in the tissues and organs of rabbits was inhibited to a certain extent.At 14 days after vaccination,the Tp load of the Tp0971 group decreased,which was significantly lower than that of the control group and the blank group(P<0.05).Conclusion Rabbits infected with Tp showed clinical symptoms similar to those of human syphilis,and the Tp load of each organ tissue showed a cyclical and dynamic change of decreasing and increasing throughout the infection process.Tp0971 immunization has a beneficial effect on the improvement of clinical signs and suppression of Tp load in Tp-infected rabbits,but does not completely remove Tp from the host.