Institute of Immunology, PLA, Third Military Medical University, 30 Gaotanyan Street, Chongqing 400038, PR China.
BMC Immunol. 2009 Dec 3;10:61. doi: 10.1186/1471-2172-10-61.
The spike (S) protein is a major structural glycoprotein of coronavirus (CoV), the causal agent of severe acute respiratory syndrome (SARS). The S protein is a potent target for SARS-specific cell-mediated immune responses. However, the mechanism CoV pathogenesis in SARS and the role of special CTLs in virus clearance are still largely uncharacterized. Here, we describe a study that leads to the identification of a novel HLA-A*0201-restricted epitope from conserved regions of S protein.
First, different SARS-CoV sequences were analyzed to predict eight candidate peptides from conserved regions of the S protein based upon HLA-A0201 binding and proteosomal cleavage. Four of eight candidate peptides were tested by HLA-A0201 binding assays. Among the four candidate peptides, Sp8 (S958-966, VLNDILSRL) induced specific CTLs both ex vivo in PBLs of healthy HLA-A2+ donors and in HLA-A2.1/Kb transgenic mice immunized with a plasmid encoding full-length S protein. The immunized mice released IFN-gamma and lysed target cells upon stimulation with Sp8 peptide-pulsed autologous dendritic cells in comparison to other candidates.
These results suggest that Sp8 is a naturally processed epitope. We propose that Sp8 epitope should help in the characterization of mechanisms of virus control and immunopathology in SARS-CoV infection.
刺突（S）蛋白是冠状病毒（CoV）的主要结构糖蛋白，是严重急性呼吸系统综合症（SARS）的病原体。S 蛋白是 SARS 特异性细胞介导免疫反应的主要靶标。然而，CoV 在 SARS 中的发病机制以及特殊 CTL 在清除病毒中的作用在很大程度上仍未得到阐明。在这里，我们描述了一项研究，该研究导致鉴定出 S 蛋白保守区域中的一种新型 HLA-A*0201 限制性表位。
首先，分析了不同的 SARS-CoV 序列，根据 HLA-A0201 结合和蛋白酶体切割，从 S 蛋白的保守区域预测了 8 个候选肽。对 8 个候选肽中的 4 个进行了 HLA-A0201 结合测定。在这 4 个候选肽中，Sp8（S958-966，VLNDILSRL）在健康 HLA-A2+供体的 PBL 中以及在接种了全长 S 蛋白编码质粒的 HLA-A2.1/Kb 转基因小鼠中均诱导了特异性 CTL。与其他候选肽相比，免疫后的小鼠在 Sp8 肽脉冲自身树突状细胞刺激下释放 IFN-γ并裂解靶细胞。
这些结果表明 Sp8 是一种天然加工的表位。我们提出 Sp8 表位应该有助于 SARS-CoV 感染中病毒控制和免疫病理学机制的特征。
