HIV-1 Neutralizing Antibodies Display Dual Recognition of the Primary and Coreceptor Binding Sites and Preferential Binding to Fully Cleaved Envelope Glycoproteins
HIV-1 Neutralizing Antibodies Display Dual Recognition of the Primary and Coreceptor Binding Sites and Preferential Binding to Fully Cleaved Envelope Glycoproteins
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DOI：
10.1128/jvi.01543-12
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发表时间：
2012-10-01
影响因子：
5.4
通讯作者：
Wyatt, Richard T.
中科院分区：
文献类型：
--
作者：
Li, Yuxing;O'Dell, Sijy;Wyatt, Richard T.
gp 120的CD 4结合位点（CD 4 bs）和辅助受体结合位点（CoRbs）是HIV-1包膜糖蛋白（Env）的两个功能保守元件。我们先前定义了HIV-1感染者血清中存在的CD 4 b s中和抗体，随后从记忆B细胞群中分离出CD 4 b s特异性单克隆抗体（MAb）VRC 01和VRC 03。由于该供体的血清似乎也含有CoRbs的中和抗体，我们采用了基于差异荧光激活细胞分选仪（FACS）的分选策略，该分选策略使用具有CoRbs敲除突变（I420 R）的Env三聚体来分离特异性B细胞。从这些细胞中回收MAb VRC 06，其遗传序列使我们能够鉴定称为VRC 06 b的克隆相对物，其使用表面重塑的核心gp 120探针及其同源CD 4 bs敲除突变体从先前的细胞分选中分离。VRC 06和VRC 06 b分别中和了22%和44%的测试病毒。表位作图研究显示，这两种单克隆抗体对gp 120 CoRbs和CD 4 bs中的突变敏感，并且可以交叉阻断CD 4 bs和CoRbs单克隆抗体与gp 120的结合。精细映射表明gp 120桥接片内的接触和第三主要可变区（V3）的碱基，它们是CoRb的元件。细胞表面结合试验表明，完全切割的Env三聚体的优先识别超过未切割的三聚体。因此，VRC 06和VRC 06 b是Env三聚体前体裂解敏感的中和MAb，其结合与HIV-1受体一级和二级结合位点重叠的gp 120区域。
The gp120 CD4 binding site (CD4bs) and coreceptor binding site (CoRbs) are two functionally conserved elements of the HIV-1 envelope glycoproteins (Env). We previously defined the presence of CD4bs-neutralizing antibodies in the serum of an HIV-1-infected individual and subsequently isolated the CD4bs-specific monoclonal antibodies (MAbs) VRC01 and VRC03 from the memory B cell population. Since this donor's serum also appeared to contain neutralizing antibodies to the CoRbs, we employed a differential fluorescence-activated cell sorter (FACS)-based sorting strategy using an Env trimer possessing a CoRbs knockout mutation (I420R) to isolate specific B cells. The MAb VRC06 was recovered from these cells, and its genetic sequence allowed us to identify a clonal relative termed VRC06b, which was isolated from a prior cell sort using a resurfaced core gp120 probe and its cognate CD4bs knockout mutant. VRC06 and VRC06b neutralized 22% and 44% of viruses tested, respectively. Epitope mapping studies revealed that the two MAbs were sensitive to mutations in both the gp120 CoRbs and the CD4bs and could cross-block binding of both CD4bs and CoRbs MAbs to gp120. Fine mapping indicated contacts within the gp120 bridging sheet and the base of the third major variable region (V3), which are elements of the CoRbs. Cell surface binding assays demonstrated preferential recognition of fully cleaved Env trimers over uncleaved trimers. Thus, VRC06 and VRC06b are Env trimer precursor cleavage-sensitive neutralizing MAbs that bind to a region of gp120 that overlaps both the primary and the secondary HIV-1 receptor binding sites.