Potent Neutralization of Vaccinia Virus by Divergent Murine Antibodies Targeting a Common Site of Vulnerability in L1 Protein
Potent Neutralization of Vaccinia Virus by Divergent Murine Antibodies Targeting a Common Site of Vulnerability in L1 Protein
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DOI：
10.1128/jvi.01491-14
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发表时间：
2014-10-01
影响因子：
5.4
通讯作者：
Xiang, Yan
中科院分区：
文献类型：
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作者：
Kaever, Thomas;Meng, Xiangzhi;Xiang, Yan
痘苗病毒 (VACV) L1 是病毒中和的重要靶标，已被包含在针对正痘病毒的多组分 DNA 或蛋白质疫苗中。为了进一步了解抗 L1 抗体的保护机制，我们生成了五种鼠抗 L1 单克隆抗体 (MAb)，它们聚集成 3 个不同的表位组。虽然两组抗 L1 抗体未能中和，但一组 3 种 MAb 以不依赖同种型和补体的方式有效中和 VACV。这与针对主要 VACV 包膜蛋白（例如 H3、D8 或 A27）的中和抗体形成对比，后者无法完全中和 VACV，除非抗体是补体固定同种型并且存在补体。与非中和性抗L1 MAb相比，中和抗体以明显更高的亲和力与重组L1蛋白结合，并且还可以与病毒体结合。通过使用多种技术，包括中和逃逸突变体的分离、氢/氘交换质谱和X射线晶体学，将中和抗体的表位映射到以Asp35作为关键残基的构象表位。该表位与 7D11 的表位相似，7D11 是先前描述的有效 VACV 中和抗体。该表位主要由重链的CDR1和CDR2识别，它们在识别该表位的抗体中高度保守。然而，这些抗体具有不同的轻链和重链 CDR3 序列。我们的研究表明，具有 Asp35 的构象 L1 表位是不同抗体组有效中和的常见脆弱点。 重要性痘苗病毒（天花活疫苗）是人类历史上最成功的疫苗之一，但它所带来的风险水平对于当前人群来说已变得无法接受。研究天花疫苗的免疫保护机制对于了解成功疫苗的基本原理以及开发针对高致病性正痘病毒的下一代更安全的疫苗具有重要意义。我们通过开发针对痘苗病毒的有效中和抗体并全面表征其表位来研究天花疫苗中的抗体靶点。我们在痘苗病毒 L1 蛋白中发现了一个位点，作为一组高效鼠中和抗体的靶标。对抗体-抗原复合物结构和抗体基因序列的分析揭示了如何从免疫小鼠中引发这些有效的中和抗体。
Vaccinia virus (VACV) L1 is an important target for viral neutralization and has been included in multicomponent DNA or protein vaccines against orthopoxviruses. To further understand the protective mechanism of the anti-L1 antibodies, we generated five murine anti-L1 monoclonal antibodies (MAbs), which clustered into 3 distinct epitope groups. While two groups of anti-L1 failed to neutralize, one group of 3 MAbs potently neutralized VACV in an isotype- and complement-independent manner. This is in contrast to neutralizing antibodies against major VACV envelope proteins, such as H3, D8, or A27, which failed to completely neutralize VACV unless the antibodies are of complement-fixing isotypes and complement is present. Compared to non-neutralizing anti-L1 MAbs, the neutralization antibodies bound to the recombinant L1 protein with a significantly higher affinity and also could bind to virions. By using a variety of techniques, including the isolation of neutralization escape mutants, hydrogen/deuterium exchange mass spectrometry, and X-ray crystallography, the epitope of the neutralizing antibodies was mapped to a conformational epitope with Asp35 as the key residue. This epitope is similar to the epitope of 7D11, a previously described potent VACV neutralizing antibody. The epitope was recognized mainly by CDR1 and CDR2 of the heavy chain, which are highly conserved among antibodies recognizing the epitope. These antibodies, however, had divergent light-chain and heavy-chain CDR3 sequences. Our study demonstrates that the conformational L1 epitope with Asp35 is a common site of vulnerability for potent neutralization by a divergent group of antibodies.IMPORTANCEVaccinia virus, the live vaccine for smallpox, is one of the most successful vaccines in human history, but it presents a level of risk that has become unacceptable for the current population. Studying the immune protection mechanism of smallpox vaccine is important for understanding the basic principle of successful vaccines and the development of next-generation, safer vaccines for highly pathogenic orthopoxviruses. We studied antibody targets in smallpox vaccine by developing potent neutralizing antibodies against vaccinia virus and comprehensively characterizing their epitopes. We found a site in vaccinia virus L1 protein as the target of a group of highly potent murine neutralizing antibodies. The analysis of antibody-antigen complex structure and the sequences of the antibody genes shed light on how these potent neutralizing antibodies are elicited from immunized mice.