The mannose-dependent epitope for neutralizing antibody 2G12 on human immunodeficiency virus type 1 glycoprotein gp120
The mannose-dependent epitope for neutralizing antibody 2G12 on human immunodeficiency virus type 1 glycoprotein gp120
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DOI：
10.1128/jvi.76.14.7293-7305.2002
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发表时间：
2002-07-01
影响因子：
5.4
通讯作者：
Moore, JP
中科院分区：
文献类型：
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作者：
Sanders, RW;Venturi, M;Moore, JP
我们分析了人免疫缺陷病毒1型（HIV-1）gp 120表面糖蛋白上的广泛中和人单克隆抗体（MAb）2G 12的独特表位。序列分析，集中在多个HIV-1分离株的相关残基的保守性上，改进了先前通过置换诱变定义的表位（A. Trkola，M. Purtscher，T.穆斯特尔角Ballaun，A. Buchacher，N. Sullivan，K. Srinivasan，J. Sodroski，J. P.摩尔和H. Katinger，J. Virol. 70：1100-1108，1996）。在生物化学研究中，我们用已知特异性的各种糖苷酶消化重组gp 120，并表明当用甘露聚糖酶处理gp 120时，2G 12表位丢失。使用计算分析来定位病毒体相关包膜糖蛋白复合物背景下的表位，以确定周围表面的变异性，并计算可能的聚糖和多肽表位组分的表面可及性。总之，这些分析表明2G 12表位集中在残基295、332和392的高甘露糖和/或杂合聚糖上，在任一侧翼具有来自386和448的外周聚糖。该表位是甘露糖依赖性的，主要由碳水化合物组成，可能没有直接参与gp 120多肽表面。它位于与CD 4结合面正交的面上，位于与辅助受体结合相关的表面接近但不同的表面上。它在其他高度可变的gp 120表面中的保守性表明2G 12结合位点的功能作用，可能与HIV-1对DC-SIGN或相关凝集素的甘露糖依赖性附着有关，这些凝集素促进病毒进入易感靶细胞。
We have analyzed the unique epitope for the broadly neutralizing human monoclonal antibody (MAb) 2G12 on the gp120 surface glycoprotein of human immunodeficiency virus type 1 (HIV-1). Sequence analysis, focusing on the conservation of relevant residues across multiple HIV-1 isolates, refined the epitope that was defined previously by substitutional mutagenesis (A. Trkola, M. Purtscher, T. Muster, C. Ballaun, A. Buchacher, N. Sullivan, K. Srinivasan, J. Sodroski, J. P. Moore, and H. Katinger, J. Virol. 70:1100-1108, 1996). In a biochemical study, we digested recombinant gp120 with various glycosidase enzymes of known specificities and showed that the 2G12 epitope is lost when gp120 is treated with mannosidases. Computational analyses were used to position the epitope in the context of the virion-associated envelope glycoprotein complex, to determine the variability of the surrounding surface, and to calculate the surface accessibility of possible glycan- and polypeptide-epitope components. Together, these analyses suggest that the 2G12 epitope is centered on the high-mannose and/or hybrid glycans of residues 295, 332, and 392, with peripheral glycans from 386 and 448 on either flank. The epitope is mannose dependent and composed primarily of carbohydrate, with probably no direct involvement of the gp120 polypeptide surface. It resides on a face orthogonal to the CD4 binding face, on a surface proximal to, but distinct from, that implicated in coreceptor binding. Its conservation amidst an otherwise highly variable gp120 surface suggests a functional role for the 2G12 binding site, perhaps related to the mannose-dependent attachment of HIV-1 to DC-SIGN or related lectins that facilitate virus entry into susceptible target cells.