Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
Laboratory of Molecular Immunology, Rockefeller University, New York, NY 10065, USA.
Sci Immunol. 2023 Feb 17;8(80):eade6364. doi: 10.1126/sciimmunol.ade6364. Epub 2023 Feb 10.
Passive transfer of broadly neutralizing anti-HIV-1 antibodies (bNAbs) protects against infection, and therefore, eliciting bNAbs by vaccination is a major goal of HIV-1 vaccine efforts. bNAbs that target the CD4 binding site (CD4bs) on HIV-1 Env are among the most broadly active, but to date, responses elicited against this epitope in vaccinated animals have lacked potency and breadth. We hypothesized that CD4bs bNAbs resembling the antibody IOMA might be easier to elicit than other CD4bs antibodies that exhibit higher somatic mutation rates, a difficult-to-achieve mechanism to accommodate Env's N276 N-glycan, and rare five-residue light chain complementarity-determining region 3. As an initial test of this idea, we developed IOMA germline-targeting Env immunogens and evaluated a sequential immunization regimen in transgenic mice expressing germline-reverted IOMA. These mice developed CD4bs epitope-specific responses with heterologous neutralization, and cloned antibodies overcame neutralization roadblocks, including accommodating the N276 glycan, with some neutralizing selected HIV-1 strains more potently than IOMA. The immunization regimen also elicited CD4bs-specific responses in mice containing polyclonal antibody repertoires as well as rabbits and rhesus macaques. Thus, germline targeting of IOMA-class antibody precursors represents a potential vaccine strategy to induce CD4bs bNAbs.
被动转移广谱中和抗 HIV-1 抗体(bNAbs)可预防感染,因此,通过疫苗接种诱导 bNAbs 是 HIV-1 疫苗研究的主要目标。靶向 HIV-1 Env 上的 CD4 结合位点(CD4bs)的 bNAbs 是最广泛有效的,但迄今为止,接种疫苗的动物针对该表位产生的反应缺乏效力和广度。我们假设,类似于 IOMA 的 CD4bs bNAbs 可能比其他具有更高体细胞突变率的 CD4bs 抗体更容易产生,而这种机制难以适应 Env 的 N276 N-糖基化,并且轻链互补决定区 3 的稀有五残基。作为对该想法的初步测试,我们开发了针对 IOMA 种系的 Env 免疫原,并在表达种系重排 IOMA 的转基因小鼠中评估了序贯免疫方案。这些小鼠产生了具有异源中和作用的 CD4bs 表位特异性反应,并且克隆抗体克服了中和障碍,包括适应 N276 糖基化,一些中和选择的 HIV-1 株比 IOMA 更有效。该免疫方案还在含有多克隆抗体库的小鼠以及兔子和恒河猴中诱导了 CD4bs 特异性反应。因此,针对 IOMA 类抗体前体的种系靶向代表了诱导 CD4bs bNAbs 的一种潜在疫苗策略。
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