Receptor-binding domain of severe acute respiratory syndrome coronavirus spike protein contains multiple conformation-dependent epitopes that induce highly potent neutralizing antibodies
Receptor-binding domain of severe acute respiratory syndrome coronavirus spike protein contains multiple conformation-dependent epitopes that induce highly potent neutralizing antibodies
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DOI：
10.4049/jimmunol.174.8.4908
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发表时间：
2005-04-15
影响因子：
4.4
通讯作者：
Jiang, SB
中科院分区：
文献类型：
--
作者：
He, YX;Lu, H;Jiang, SB
严重急性呼吸综合征相关冠状病毒（SARS-CoV）的刺突(S)蛋白是能够诱导保护性免疫的主要抗原决定因子。最近，SARS-CoV S蛋白上的一个小片段（残基318-510）被鉴定为最小受体结合域（RBD），它介导病毒与血管紧张素转换酶2（易感细胞上的功能受体）的结合。在这项研究中，我们证明了一种与人IgG1 Fe片段连接的含有RBD的融合蛋白（命名为RBD- fc）在免疫小鼠中诱导了高滴度的RBD特异性抗体。小鼠抗血清能有效中和SARS冠状病毒和SARS假病毒感染，平均50%的中和效价分别为1/15,360和1/24,737。S蛋白RBD上的中和决定因子通过从免疫小鼠中分离的27个单抗进行鉴定。通过酶联免疫吸附试验和结合竞争试验鉴定了6组构象依赖表位Conf - vi和2组相邻的线性表位。Conf IV和Conf V单抗显著阻断RBD-Fc与血管紧张素转换酶2的结合，表明它们的表位与S蛋白的受体结合位点重叠。大多数识别构象表位的单克隆抗体（25个中的23个）对SARS假病毒具有有效的中和活性，50%的中和剂量范围为0.005 ~ 6.569 μ g/ml。因此，SARS S蛋白的RBD含有多个构象表位，能够诱导有效的中和性Ab反应，是开发疫苗和免疫疗法的重要靶点。
The spike (S) protein of severe acute respiratory syndrome associated coronavirus (SARS-CoV) is a major antigenic determinant capable of inducing protective immunity. Recently, a small fragment on the SARS-CoV S protein (residues 318-510) was characterized as a minimal receptor-binding domain (RBD), which mediates virus binding to angiotensin-converting enzyme 2, the functional receptor on susceptible cells. In this study, we demonstrated that a fusion protein containing RBD linked to human IgG1 Fe fragment (designated RBD-Fc) induced high titer of RBD-specific Abs in the immunized mice. The mouse antisera effectively neutralized infection by both SARS-CoV and SARS pseudovirus with mean 50 % neutralization titers of 1/15,360 and 1/24,737, respectively. The neutralization determinants on the RBD of S protein were characterized by a panel of 27 mAbs isolated from the immunized mice. Six groups of conformation-dependent epitopes, designated as Conf I-VI, and two adjacent linear epitopes were identified by ELISA and binding competition assays. The Conf IV and Conf V mAbs significantly blocked RBD-Fc binding to angiotensin-converting enzyme 2, suggesting that their epitopes overlap with the receptor-binding sites in the S protein. Most of the mAbs (23 of 25) that recognized the conformational epitopes possessed potent neutralizing activities against SARS pseudovirus with 50 % neutralizing dose ranging from 0.005 to 6.569 mu g/ml. Therefore, the RBD of SARS S protein contains multiple conformational epitopes capable of inducing potent neutralizing Ab responses, and is an important target site for developing vaccines and immunotherapeutics.