Lewinski M A, Miller J N, Champion C I, Walker E M, Borenstein L A, Gayek R J, Lovett M A, Blanco D R
Department of Microbiology and Immunology, University of California School of Medicine, Los Angeles 90024.
Sex Transm Dis. 1995 Jan-Feb;22(1):31-8. doi: 10.1097/00007435-199501000-00006.
The authors have previously shown that complement-dependent treponemicidal antibody measured by the "washed-killing" assay is directed exclusively against surface-exposed targets on Treponema pallidum, presumably the Treponema pallidum rare outer membrane proteins detected by freeze-fracture electron microscopy.
Because immune mechanisms against Treponema pallidum rare outer membrane proteins are likely to be central to a protective host response, it was examined whether a relationship could be established between treponemicidal levels as measured by the "washed-killing" assay and host immunity in experimental syphilis.
Three groups of Treponema pallidum-infected rabbits were treated curatively with penicillin at 9 days, 30 days, and 6 months post-infection to generate animals with varying degrees of immunity to challenge re-infection. The level of complement-dependent treponemicidal activity in sera obtained before infection (basal) and before intradermal challenge was determined by the "washed-killing" assay and compared with that detected using conventional in vitro immobilization.
Using the "washed-killing" assay, a close quantitative correlation as measured by a treponemal immobilizing endpoint titer was demonstrable between prechallenge treponemicidal antibody and the status of immunity to re-infection. Sera from rabbits completely susceptible to symptomatic and disseminated asymptomatic re-infection lacked treponemicidal antibody. Sera from challenged rabbits with a relatively low degree of immunity to symptomatic disease showed endpoints of < or = 4. Rabbits with a relatively high degree of immunity to symptomatic reinfection and resistant to disseminated disease had endpoints that ranged from 6 to 96. Rabbits completely resistant to challenge exhibited endpoints ranging from 96 to 128.
Treponemicidal antibody measured by the "washed-killing" assay correlated closely with the status of immunity in experimental rabbit syphilis. Thus, antibody measured by this assay may be directed against key protective Treponema pallidum surface immunogens.
作者之前已经表明，通过“洗涤杀伤”试验测定的补体依赖性杀梅毒螺旋体抗体仅针对梅毒螺旋体表面暴露的靶点，推测是通过冷冻断裂电子显微镜检测到的梅毒螺旋体稀有外膜蛋白。
由于针对梅毒螺旋体稀有外膜蛋白的免疫机制可能是宿主保护性反应的核心，因此研究了通过“洗涤杀伤”试验测定的杀梅毒螺旋体水平与实验性梅毒中宿主免疫力之间是否可以建立联系。
三组感染梅毒螺旋体的兔子在感染后9天、30天和6个月接受青霉素根治性治疗，以产生对再次感染具有不同程度免疫力的动物。通过“洗涤杀伤”试验测定感染前（基础）和皮内攻击前获得的血清中补体依赖性杀梅毒螺旋体活性水平，并与使用传统体外固定法检测的水平进行比较。
使用“洗涤杀伤”试验，通过梅毒螺旋体固定终点滴度测量，在攻击前杀梅毒螺旋体抗体与再次感染的免疫状态之间可证明存在密切的定量相关性。对有症状和播散性无症状再次感染完全易感的兔子血清缺乏杀梅毒螺旋体抗体。对有症状疾病免疫力相对较低的受攻击兔子血清显示终点≤4。对有症状再次感染免疫力相对较高且对播散性疾病有抵抗力的兔子终点范围为6至96。对攻击完全有抵抗力的兔子终点范围为96至128。
通过“洗涤杀伤”试验测定的杀梅毒螺旋体抗体与实验性兔梅毒的免疫状态密切相关。因此，通过该试验测定的抗体可能针对关键的保护性梅毒螺旋体表面免疫原。
