Weekes M P, Wills M R, Mynard K, Carmichael A J, Sissons J G
Department of Medicine, University of Cambridge Clinical School, Cambridge CB2 2QQ, United Kingdom.
J Virol. 1999 Mar;73(3):2099-108. doi: 10.1128/JVI.73.3.2099-2108.1999.
Human cytomegalovirus (HCMV)-specific CD8(+) cytotoxic T lymphocytes (CTL) appear to play an important role in the control of virus replication and in protection against HCMV-related disease. We have previously reported high frequencies of memory CTL precursors (CTLp) specific to the HCMV tegument protein pp65 in the peripheral blood of healthy virus carriers. In some individuals, the CTL response to this protein is focused on only a single epitope, whereas in other virus carriers CTL recognized multiple epitopes which we identified by using synthetic peptides. We have analyzed the clonal composition of the memory CTL response to four of these pp65 epitopes by sequencing the T-cell receptors (TCR) of multiple independently derived epitope-specific CTL clones, which were derived by formal single-cell cloning or from clonal CTL microcultures. In all cases, we have observed a high degree of clonal focusing: the majority of CTL clones specific to a defined pp65 peptide from any one virus carrier use only one or two different TCRs at the level of the nucleotide sequence. Among virus carriers who have the same major histocompatibility complex (MHC) class I allele, we observed that CTL from different donors that recognize the same peptide-MHC complex often used the same Vbeta segment, although other TCR gene segments and CDR3 length were not in general conserved. We have also examined the clonal composition of CTL specific to pp65 peptides in asymptomatic human immunodeficiency virus-infected individuals. We have observed a similarly focused peptide-specific CTL response. Thus, the large population of circulating HCMV peptide-specific memory CTLp in virus carriers in fact contains individual CTL clones that have undergone extensive clonal expansion in vivo.
人巨细胞病毒（HCMV）特异性CD8(+)细胞毒性T淋巴细胞（CTL）似乎在控制病毒复制及预防HCMV相关疾病中发挥重要作用。我们之前报道过，健康病毒携带者外周血中存在高频率的针对HCMV被膜蛋白pp65的记忆CTL前体（CTLp）。在一些个体中，CTL对该蛋白的反应仅集中于单个表位，而在其他病毒携带者中，CTL识别多个表位，这些表位是我们通过使用合成肽鉴定出来的。我们通过对多个独立获得的表位特异性CTL克隆的T细胞受体（TCR）进行测序，分析了针对其中四个pp65表位的记忆CTL反应的克隆组成，这些克隆是通过正式的单细胞克隆或从克隆CTL微培养物中获得的。在所有情况下，我们都观察到高度的克隆集中现象：来自任何一名病毒携带者的、针对特定pp65肽的大多数CTL克隆在核苷酸序列水平上仅使用一两种不同的TCR。在具有相同主要组织相容性复合体（MHC）I类等位基因的病毒携带者中，我们观察到，识别相同肽-MHC复合体的不同供体的CTL通常使用相同的Vβ片段，尽管其他TCR基因片段和CDR3长度一般并不保守。我们还检查了无症状人类免疫缺陷病毒感染个体中针对pp65肽的CTL的克隆组成。我们观察到了类似的集中于肽的特异性CTL反应。因此，病毒携带者中大量循环的HCMV肽特异性记忆CTLp实际上包含在体内经历了广泛克隆扩增的单个CTL克隆。
