Lesénéchal Mylène, Becquart Laurence, Lacoux Xavier, Ladavière Laurent, Baida Renata C P, Paranhos-Baccalà Glaucia, da Silveira José Franco
UMR 2714 CNRS-bioMérieux, IFR 128 BioScience Lyon-Gerland, CERVI-21, Lyon, France.
Clin Diagn Lab Immunol. 2005 Feb;12(2):329-33. doi: 10.1128/CDLI.12.2.329-333.2005.
Tc40 is an immunodominant antigen present in natural Trypanosoma cruzi infections. This immunogen was thoroughly mapped by using overlapping amino acid sequences identified by gene cloning and chemical peptide synthesis. To map continuous epitopes of the Tc40 antigen, an epitope expression library was constructed and screened with sera from human chagasic patients. A major, linear B-cell epitope spanning residues 403 to 426 (PAKAAAPPAA) was identified in the central domain of Tc40. A synthetic peptide spanning this region reacted strongly with 89.8% of the serum samples from T. cruzi-infected individuals. This indicates that the main antigenic site is defined by the linear sequence of the peptide rather than a conformation-dependent structure. The major B-cell epitope of Tc40 shares a high degree of sequence identity with T. cruzi ribosomal and RNA binding proteins, suggesting the existence of cross-reactivity among these molecules.
Tc40是天然克氏锥虫感染中存在的一种免疫显性抗原。通过使用基因克隆和化学肽合成鉴定的重叠氨基酸序列，对这种免疫原进行了全面定位。为了定位Tc40抗原的连续表位，构建了一个表位表达文库，并用恰加斯病患者的血清进行筛选。在Tc40的中央结构域中鉴定出一个主要的线性B细胞表位，其跨越残基403至426（PAKAAAPPAA）。跨越该区域的合成肽与89.8%的克氏锥虫感染个体的血清样本发生强烈反应。这表明主要抗原位点由肽的线性序列定义，而非构象依赖性结构。Tc40的主要B细胞表位与克氏锥虫核糖体和RNA结合蛋白具有高度的序列同一性，提示这些分子之间存在交叉反应性。
