Zeng L, Kurane I, Okamoto Y, Ennis F A, Brinton M A
Department of Biology, Georgia State University, Atlanta 30303, USA.
J Virol. 1996 May;70(5):3108-17. doi: 10.1128/JVI.70.5.3108-3117.1996.
The majority of T-cell clones derived from a donor who experienced dengue illness following receipt of a live experimental dengue virus type 3 (DEN3) vaccine cross-reacted with all four serotypes of dengue virus, but some were serotype specific or only partially cross-reactive. The nonstructural protein, NS3, was immuno-dominant in the CD4+ T-cell response of this donor. The epitopes of four NS3-specific T-cell clones were analyzed. JK15 and JK13 recognized only DEN3 NS3, while JK44 recognized DEN1, DEN2, and DEN3 NS3 and JK5 recognized DEN1, DEN3, and West Nile virus NS3. The epitopes recognized by these clones on the DEN3 NS3 protein were localized with recombinant vaccinia viruses expressing truncated regions of the NS3 gene, and then the minimal recognition sequence was mapped with synthetic peptides. Amino acids critical for T-cell recognition were assessed by using peptides with amino acid substitutions. One of the serotype-specific clones (JK13) and the subcomplex- and flavivirus-cross-reactive clone (JK5) recognized the same core epitope, WITDFVGKTVW. The amino acid at the sixth position of this epitope is critical for recognition by both clones. Sequence analysis of the T-cell receptors of these two clones showed that they utilize different VP chains. The core epitopes for the four HLA-DR15-restricted CD4+ CTL clones studied do not contain motifs similar to those proposed by previous studies on endogenous peptides eluted from HLA-DR15 molecules. However, the majority of these dengue virus NS3 core epitopes have a positive amino acid (K or R) at position 8 or 9. Our results indicate that a single epitope can induce T cells with different virus specificities despite the restriction of these T cells by the same HLA-DR15 allele. This finding suggests a previously unappreciated level of complexity for interactions between human T-cell receptors and viral epitopes with very similar sequences on infected cells.
大多数源自一名在接种活的实验性3型登革病毒（DEN3）疫苗后感染登革热的供体的T细胞克隆与登革病毒的所有四种血清型发生交叉反应，但有些是血清型特异性的或仅部分交叉反应。非结构蛋白NS3在该供体的CD4+ T细胞应答中具有免疫优势。分析了四个NS3特异性T细胞克隆的表位。JK15和JK13仅识别DEN3 NS3，而JK44识别DEN1、DEN2和DEN3 NS3，JK5识别DEN1、DEN3和西尼罗河病毒NS3。利用表达NS3基因截短区域的重组痘苗病毒对这些克隆在DEN3 NS3蛋白上识别的表位进行定位，然后用合成肽绘制最小识别序列。通过使用具有氨基酸取代的肽评估对T细胞识别至关重要的氨基酸。其中一个血清型特异性克隆（JK13）和亚复合物及黄病毒交叉反应克隆（JK5）识别相同的核心表位WITDFVGKTVW。该表位第六位的氨基酸对两个克隆的识别至关重要。对这两个克隆的T细胞受体进行序列分析表明，它们利用不同的Vβ链。所研究的四个HLA-DR15限制性CD4+ CTL克隆的核心表位不包含与先前关于从HLA-DR15分子洗脱的内源性肽的研究所提出的基序相似的基序。然而，这些登革病毒NS3核心表位中的大多数在第8或9位具有正氨基酸（K或R）。我们的结果表明，尽管这些T细胞受相同的HLA-DR15等位基因限制，但单个表位可诱导具有不同病毒特异性的T细胞。这一发现提示了人类T细胞受体与感染细胞上序列非常相似的病毒表位之间相互作用的复杂性，而这种复杂性此前未被充分认识。
