STERIC HINDRANCE OF ANTIBODY-BINDING TO SURFACE-PROTEINS OF COXIELLA-BURNETII BY PHASE-I LIPOPOLYSACCHARIDE
STERIC HINDRANCE OF ANTIBODY-BINDING TO SURFACE-PROTEINS OF COXIELLA-BURNETII BY PHASE-I LIPOPOLYSACCHARIDE
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DOI：
10.1128/iai.56.4.802-807.1988
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发表时间：
1988-04-01
影响因子：
3.1
通讯作者：
HACKSTADT, T
中科院分区：
文献类型：
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作者：
HACKSTADT, T
比较了表面蛋白抗原在布氏柯克斯体I期和无毒II期细胞上的暴露情况。虽然抗II相抗体不与天然完整的I相细胞表面结合，但如果将I相蛋白溶解于十二烷基硫酸钠-聚丙烯酰胺凝胶电泳法并通过免疫印迹分析，它们会与I相蛋白结合。此外，通过免疫荧光分析、直接抗体结合和使用蛋白A-胶体金偶联物的免疫电子显微镜显示，三氯乙酸去除I相脂多糖(LPS)暴露了表面蛋白与抗II相抗体的反应。基于这些观察，提出了一个简单的相变模型来解释关于第二相抗原(S)身份的明显相互冲突的概念。该模型表明，I相脂多糖在空间上阻碍了抗II相抗体与多种共享蛋白抗原的结合，其中任何一个都可能赋予II相特异性。通过出现更截短的内毒素(II期)或提取光滑的I型内毒素，暴露这些共享的蛋白抗原，可以获得抗体，从而赋予II期明显的血清特异性。
The exposure of surface protein antigens on virulent phase I Coxiella brunetii was compared with that on avirulent phase II cells. Although anti-phase II antibodies did not bind to the surfaces of native intact phase I cells, they bound to phase I proteins if the proteins were solubilized for sodium dodecyl sulfate-polyacrylamide gel electrophoresis and analyzed by immunoblotting. In addition, removal of the phase I lipopolysaccharide (LPS) by trichloroacetic acid exposed surface proteins for reactivity with anti-phase II antibodies, as shown by immunofluorescence assays, direct antibody binding, and immunoelectron microscopy using protein A-colloidal gold conjugates. Based on these observations, a simple model of phase variation is proposed to explain the apparently conflicting notions of the identity of the phase II antigen(s). The model suggests that the phase I LPS sterically hinders access of anti-phase II antibodies to a multitude of shared protein antigens, any one of which may confer phase II specificity. Exposure of these shared protein antigens through the appearance of a more truncated LPS (phase II) or extraction of the smooth-type phase I LPS allows antibody accessibility and therefore confers apparent phase II serospecificity.