Dependence on a variable residue limits the breadth of an HIV MPER neutralizing antibody, despite convergent evolution with broadly neutralizing antibodies.
Dependence on a variable residue limits the breadth of an HIV MPER neutralizing antibody, despite convergent evolution with broadly neutralizing antibodies.
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DOI：
10.1371/journal.ppat.1010450
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发表时间：
2022-09
期刊：
影响因子：
6.7
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靶向HIV gp 41包膜的近膜外部区域（MPER）的广泛中和抗体（bNAb），如4 E10、VRC42.01和PGZL 1，可以中和>80%的病毒。这三种针对MPR的单克隆抗体共享生殖系抗体基因（IGHV 1 -69和IGKV 3 -20）并形成bNAb表位类别。此外，已知这两个谱系内朝向CDRH 3中的111.2GW 111.3基序的趋同进化增强中和效力。我们之前已经分离出了MPER中和抗体CAP 206-CH 12，其使用这些相同的种系重链和轻链基因，但缺乏广度（仅中和6%的异源病毒）。对CAP 206-CH 12谱系进行了三年的纵向测序，揭示了在一些谱系成员中类似的朝向111.2GW 111.3的趋同进化。CAP 206-CH 12从111.2GL111.3突变为111.2GW111.3并将双GWGW基序引入CAP 206-CH 12适度改善了中和效力（2.5-3倍），但未达到VRC42.01、4 E10或PGZL 1的效力水平。为了探索效力/宽度的缺乏，进行病毒诱变以定位CAP 206-CH 12表位。这表明CAP 206-CH 12依赖于D 674，D 674是MPER溶剂暴露弯头处的高度可变残基。相比之下，VRC42.01、PGZL 1和4 E10依赖于面向MPER疏水补丁的高度保守残基（W 672、F673、T676和W 680）。因此，虽然CAP 206-CH 12、VRC42.01、PGZL 1和4 E10共享生殖系基因并显示出趋同进化的一些证据，但它们对不同氨基酸的依赖性（这影响了与MPER结合的方向）导致了宽度和效力的差异。这些数据具有针对MPER表位的HIV疫苗设计的意义。生殖系靶向免疫原是一种很有前途的HIV疫苗设计策略。这种方法依赖于广泛中和抗体（bNAb）类别的鉴定，其使用相同的种系抗体基因靶向相同的病毒表位。在这里，我们比较了四种HIV包膜MPR定向抗体（4 E10、VRC42.01、PGZL 1和CAP 206-CH 12），尽管它们具有共享的抗体基因，但显示出不同的中和谱。我们表明，CAP 206-CH 12是依赖于一个高度可变的残基在MPER，这导致在低中和宽度。相比之下，4 E10、PGZL 1和VRC42.01 mAb依赖于MPER中的高度保守残基，从而导致异常的中和宽度。我们的数据表明，虽然需要bNAb表位类别内的共享种系基因，但在某些情况下，这些基因不足以产生中和宽度，并且MPER免疫原将需要触发对保守位点的应答。
Broadly neutralizing antibodies (bNAbs) that target the membrane-proximal external region (MPER) of HIV gp41 envelope, such as 4E10, VRC42.01 and PGZL1, can neutralize >80% of viruses. These three MPER-directed monoclonal antibodies share germline antibody genes (IGHV1-69 and IGKV3-20) and form a bNAb epitope class. Furthermore, convergent evolution within these two lineages towards a 111.2GW111.3 motif in the CDRH3 is known to enhance neutralization potency. We have previously isolated an MPER neutralizing antibody, CAP206-CH12, that uses these same germline heavy and light chain genes but lacks breadth (neutralizing only 6% of heterologous viruses). Longitudinal sequencing of the CAP206-CH12 lineage over three years revealed similar convergent evolution towards 111.2GW111.3 among some lineage members. Mutagenesis of CAP206-CH12 from 111.2GL111.3 to 111.2GW111.3 and the introduction of the double GWGW motif into CAP206-CH12 modestly improved neutralization potency (2.5–3-fold) but did not reach the levels of potency of VRC42.01, 4E10 or PGZL1. To explore the lack of potency/breadth, viral mutagenesis was performed to map the CAP206-CH12 epitope. This indicated that CAP206-CH12 is dependent on D674, a highly variable residue at the solvent-exposed elbow of MPER. In contrast, VRC42.01, PGZL1 and 4E10 were dependent on highly conserved residues (W672, F673, T676, and W680) facing the hydrophobic patch of the MPER. Therefore, while CAP206-CH12, VRC42.01, PGZL1 and 4E10 share germline genes and show some evidence of convergent evolution, their dependence on different amino acids, which impacts orientation of binding to the MPER, result in differences in breadth and potency. These data have implications for the design of HIV vaccines directed at the MPER epitope. Germline-targeting immunogens are a promising HIV vaccine design strategy. This approach is reliant on the identification of broadly neutralizing antibody (bNAb) classes, which use the same germline antibody genes to target the same viral epitopes. Here, we compare four HIV Envelope MPER-directed antibodies (4E10, VRC42.01, PGZL1 and CAP206-CH12) that despite having shared antibody genes, show distinct neutralization profiles. We show that CAP206-CH12 is dependent on a highly variable residue in the MPER, which results in low neutralization breadth. In contrast, the 4E10, PGZL1 and VRC42.01 mAbs are dependent on highly conserved residues in the MPER, resulting in exceptional neutralization breadth. Our data suggest that while shared germline genes within bNAb epitope classes are required, in some cases these are not sufficient to produce neutralization breadth, and MPER immunogens will need to trigger responses to conserved sites.