Hsu P L, Qin M, Norris S J, Sell S
Department of Pathology and Laboratory Medicine, University of Texas Health Science Center at Houston 77225.
Infect Immun. 1988 May;56(5):1135-43. doi: 10.1128/iai.56.5.1135-1143.1988.
Escherichia coli clones containing Treponema pallidum DNA in the pUC8 vector and secreting a 24-kilodalton antigen of T. pallidum have been isolated. Both syphilitic human and syphilis-immune rabbit sera reacted with the recombinant p24 antigen, indicating that an equivalent protein in T. pallidum is capable of eliciting antibody responses during natural infections. The p24 antigen of T. pallidum was identified by using two-dimensional gel electrophoresis and immunoblotting with monospecific anti-p24 serum. We tentatively concluded that this cloned antigen is a secreted protein or a labile or minor component of T. pallidum because (i) p24 was secreted by the recombinant E. coli cells; (ii) recombinant p24 in E. coli cells was processed into several smaller species with molecular masses ranging from 12 to 20 kilodaltons, which correlate well with the masses of secreted antigens described by others; and (iii) p24 protein appeared to be highly antigenic during natural infections, but only a very small amount of this antigen was associated with or retained by the purified organisms. The possible role of the p24 protein in determining the growth characteristics of T. pallidum is suggested by the ability of recombinant p24 to induce growth changes in E. coli cells. All E. coli colonies expressing the p24 polypeptide exhibited a flat and rough colony morphology and a filamentous growth pattern that were different from those of other E. coli cells. The DNA sequence coding for the p24 polypeptide is located on a 1.7-kilobase-pair BamHI fragment of the T. pallidum genomic DNA and is absent in the nonpathogenic Treponema phagedenis DNA. However, any possible relationship between the p24 antigen and the virulence of T. pallidum remains to be determined. In preliminary studies, rabbits immunized with the purified p24 were not protected from the infection with live T. pallidum organisms.
已分离出含有梅毒螺旋体DNA的pUC8载体大肠杆菌克隆，并分泌一种24千道尔顿的梅毒螺旋体抗原。梅毒患者血清和梅毒免疫兔血清均与重组p24抗原发生反应，表明梅毒螺旋体中的等效蛋白在自然感染期间能够引发抗体反应。梅毒螺旋体的p24抗原通过二维凝胶电泳和用单特异性抗p24血清进行免疫印迹鉴定。我们初步得出结论，这种克隆抗原是一种分泌蛋白，或者是梅毒螺旋体的不稳定或次要成分，原因如下：（i）p24由重组大肠杆菌细胞分泌；（ii）大肠杆菌细胞中的重组p24被加工成几种较小的分子，分子量范围为12至20千道尔顿，这与其他人描述的分泌抗原的分子量密切相关；（iii）p24蛋白在自然感染期间似乎具有高度抗原性，但纯化的生物体仅与极少量的这种抗原相关或保留。重组p24能够诱导大肠杆菌细胞生长变化，这提示了p24蛋白在决定梅毒螺旋体生长特性方面的可能作用。所有表达p24多肽的大肠杆菌菌落均呈现出扁平粗糙的菌落形态和丝状生长模式，与其他大肠杆菌细胞不同。编码p24多肽的DNA序列位于梅毒螺旋体基因组DNA的一个1.7千碱基对的BamHI片段上，而非致病性噬菌密螺旋体DNA中不存在该序列。然而，p24抗原与梅毒螺旋体毒力之间的任何可能关系仍有待确定。在初步研究中，用纯化的p24免疫的兔子未免受活梅毒螺旋体生物体感染的保护。
