Department of Cell Research and Immunology, George S, Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
Retrovirology. 2013 Dec 5;10:147. doi: 10.1186/1742-4690-10-147.
HIV-1 infection of target cells is mediated via the binding of the viral envelope protein, gp120, to the cell surface receptor CD4. This interaction leads to conformational rearrangements in gp120 forming or revealing CD4 induced (CD4i) epitopes which are critical for the subsequent recognition of the co-receptor required for viral entry. The CD4-bound state of gp120 has been considered a potential immunogen for HIV-1 vaccine development. Here we report on an alternative means to induce gp120 into the CD4i conformation.
Combinatorial phage display peptide libraries were screened against HIV-1 gp120 and short (14aa) peptides were selected that bind the viral envelope and allosterically induce the CD4i conformation. The lead peptide was subsequently systematically optimized for higher affinity as well as more efficient inductive activity. The peptide:gp120 complex was scrutinized with a panel of neutralizing anti-gp120 monoclonal antibodies and CD4 itself, illustrating that peptide binding does not interfere with or obscure the CD4 binding site.
Two surfaces of gp120 are considered targets for the development of cross neutralizing antibodies against HIV-1; the CD4 binding site and CD4i epitopes. By implementing novel peptides that allosterically induce the CD4i epitopes we have generated a viral envelope that presents both of these surfaces simultaneously.
HIV-1 感染靶细胞是通过病毒包膜蛋白 gp120 与细胞表面受体 CD4 的结合来介导的。这种相互作用导致 gp120 的构象重排，形成或揭示 CD4 诱导（CD4i）表位，这对于随后识别病毒进入所需的共受体至关重要。gp120 与 CD4 的结合状态被认为是 HIV-1 疫苗开发的潜在免疫原。在这里，我们报告了一种诱导 gp120 进入 CD4i 构象的替代方法。
针对 HIV-1 gp120 筛选了组合噬菌体展示肽文库，并选择了短（14aa）肽结合病毒包膜并变构诱导 CD4i 构象。随后，对先导肽进行了系统优化，以提高亲和力和诱导活性。用一组中和抗 gp120 单克隆抗体和 CD4 本身对肽：gp120 复合物进行了仔细研究，表明肽结合不会干扰或掩盖 CD4 结合位点。
gp120 的两个表面被认为是针对 HIV-1 开发交叉中和抗体的目标；CD4 结合位点和 CD4i 表位。通过实施变构诱导 CD4i 表位的新型肽，我们生成了同时呈现这两个表面的病毒包膜。
