Meyuhas Ronit, Noy Hava, Montefiori David C, Denisova Galina, Gershoni Jonathan M, Gross Gideon
Laboratory of Immunology, MIGAL - Galilee Technology Center, P.O. Box 831, Kiryat Shmona 11016, Israel.
Mol Immunol. 2005 May;42(9):1099-109. doi: 10.1016/j.molimm.2004.11.002. Epub 2004 Dec 21.
The envelope glycoprotein of HIV-1 is the principal target for entry inhibitors. The use of soluble CD4 has been found to be impractical as most clinical isolates are resistant to neutralization at feasible concentrations. CG10 is one of a small group of monoclonal antibodies specific to CD4-induced epitopes, which are structurally associated with the chemokine receptor-binding site and are capable of blocking the interaction of gp120 with its obligatory co-receptor. We have reasoned that fusing the single chain Fv of CG10 with CD4 can lead to increased HIV-1 neutralization activity and that this effect could be further enhanced by engrafting this chimeric construct onto an IgG Fc. Here we report the cloning of the genes encoding the variable regions of CG10 heavy and light chains and demonstrate that when attached to human IgG1 Fc, the single chain Fv of CG10 retains the binding properties of the original mouse antibody. Fusing CG10 single chain Fv with the gp120-binding portion of CD4 on a human IgG1 Fc backbone results in stronger binding of gp120 of different tropisms and in enhanced neutralization of laboratory-adapted strains and most, but not all, clade B and clade C isolates tested. Our findings underscore the potential use of CD4-based fusion proteins in the design of HIV immuno-therapeutics.
HIV-1的包膜糖蛋白是进入抑制剂的主要靶点。由于大多数临床分离株在可行浓度下对中和作用具有抗性，因此发现使用可溶性CD4是不切实际的。CG10是一小群针对CD4诱导表位的单克隆抗体之一，这些表位在结构上与趋化因子受体结合位点相关，并且能够阻断gp120与其必需共受体的相互作用。我们推断将CG10的单链Fv与CD4融合可导致HIV-1中和活性增加，并且通过将这种嵌合构建体嫁接到IgG Fc上可进一步增强这种效果。在此我们报告编码CG10重链和轻链可变区的基因的克隆，并证明当连接到人IgG1 Fc上时，CG10的单链Fv保留了原始小鼠抗体的结合特性。在人IgG1 Fc骨架上将CG10单链Fv与CD4的gp120结合部分融合，可导致不同嗜性的gp120更强的结合，并增强对实验室适应株以及大多数（但不是全部）测试的B组和C组分离株的中和作用。我们的发现强调了基于CD4的融合蛋白在HIV免疫治疗设计中的潜在用途。
