Benito A, Mateu M G, Villaverde A
Institut de Biologia Fonamental, Universitat Autònoma de Barcelona, Bellaterra, Spain.
Biotechnology (N Y). 1995 Aug;13(8):801-4. doi: 10.1038/nbt0895-801.
A major antigenic site (site A) of foot-and-mouth disease virus includes multiple overlapping epitopes located within the flexible G-H loop of capsid protein VP1. We have studied the antigenicity of several recombinant E. coli beta-galactosidases displaying the site A from a serotype C virus in different surface regions of the bacterial enzyme. In each one of the explored insertion sites, the recombinant peptide shows different specificity with a set of anti-virus monoclonal antibodies directed to site A. In some of them, the inserted stretch mimics better than free or haemocyanin-coupled peptide the antigenicity of site A in the intact virus. In particular, an insertion within an exposed loop involved in the activating interface of beta-galactosidase (amino acids 272 to 287) led to a significant improvement of the overall reactivity. Since insertions at this site renders proteins enzymatically active, the activating interface could be an adequate place for the presentation of foreign antigens in correctly assembled beta-galactosidase tetramers. These results also suggest that anti-virus antibodies directed against the major antigenic site of FMDV recognize different conformations of the G-H loop, which are better reproduced in some of the recombinant proteins because of the dissimilar restrictions imposed by each particular insertion site.
口蹄疫病毒的一个主要抗原位点（位点A）包含多个重叠表位，这些表位位于衣壳蛋白VP1的柔性G-H环内。我们研究了几种在细菌酶的不同表面区域展示C型病毒位点A的重组大肠杆菌β-半乳糖苷酶的抗原性。在每个探索的插入位点，重组肽与一组针对位点A的抗病毒单克隆抗体表现出不同的特异性。在其中一些位点，插入的片段比游离或与血蓝蛋白偶联的肽更好地模拟了完整病毒中位点A的抗原性。特别是，在参与β-半乳糖苷酶激活界面的暴露环内（氨基酸272至287）的插入导致整体反应性显著提高。由于在此位点的插入使蛋白质具有酶活性，激活界面可能是在正确组装的β-半乳糖苷酶四聚体中呈递外源抗原的合适位置。这些结果还表明，针对口蹄疫病毒主要抗原位点的抗病毒抗体识别G-H环的不同构象，由于每个特定插入位点施加的不同限制，这些构象在一些重组蛋白中得到了更好的再现。
