Neutralization of human immunodeficiency virus type 1 by sCD4-17b, a single-chain chimeric protein, based on sequential interaction of gp120 with CD4 and coreceptor
Neutralization of human immunodeficiency virus type 1 by sCD4-17b, a single-chain chimeric protein, based on sequential interaction of gp120 with CD4 and coreceptor
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DOI：
10.1128/jvi.77.5.2859-2865.2003
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发表时间：
2003-03-01
影响因子：
5.4
通讯作者：
Berger, EA
中科院分区：
文献类型：
--
作者：
Dey, B;Del Castillo, CS;Berger, EA
我们设计了一个新的单链嵌合蛋白，命名为sCD4-17b，用于中和人类免疫缺陷病毒1型（HIV-1）。重组蛋白含有可溶性CD4 （sCD4）结构域1和2，通过一个灵活的多肽连接体连接到17b的单链可变区构建体，17b是一种人单克隆抗体，靶向gp120上重叠的CD4诱导的保守表位。我们假设sCD4片段会结合gp120并暴露17b表位；17b片段随后结合，从而阻断辅受体相互作用并中和感染。重组痘苗病毒表达的sCD4-17b蛋白能有效中和R5分支B原代分离物，50%抑制浓度为3.2 nM (0.16 mug/ml)， 95%中和浓度为32 nM （1.6 mug/ml）。单个组分（sCD4和17b，单独或组合）在这些浓度下影响最小，表明sCD4-17b的活性反映了单个嵌合分子通过两个独立的部分同时结合gp120的能力。与先前表征的广泛交叉反应的中和单克隆抗体IgGb12、2G12和2F5相比，sCD4-17b是高效的。多个初级分离株被中和，包括先前描述为抗体耐药的两株。R5和X4菌株均发生中和，且不局限于进化枝b。然而，尽管已知存在CD4和17b的结合位点，但一些初级分离株在测试的浓度范围内不敏感。sCD4-17b在多种情况下对HIV-1进行被动免疫具有潜在的效用，包括母体传播、暴露后预防和性传播（局部杀微生物剂）。
We designed a novel single-chain chimeric protein, designated sCD4-17b, for neutralization of human immunodeficiency virus type 1 (HIV-1). The recombinant protein contains domains 1 and 2 of soluble CD4 (sCD4), connected via a flexible polypeptide linker to a single-chain variable region construct of 17b, a human monoclonal antibody that targets a conserved CD4-induced epitope on gp120 overlapping the coreceptor binding region. We hypothesized that the sCD4 moiety would bind gp120 and expose the 17b epitope; the 17b moiety would then bind, thereby blocking coreceptor interaction and neutralizing infection. The sCD4-17b protein, expressed by a recombinant vaccinia virus, potently neutralized a prototypic R5 clade B primary isolate, with a 50% inhibitory concentration of 3.2 nM (0.16 mug/ml) and >95% neutralization at 32 nM (1.6 mug/ml). The individual components (sCD4 and 17b, singly or in combination) had minimal effects at these concentrations, demonstrating that the activity of sCD4-17b reflected the ability of a single chimeric molecule to bind gp120 simultaneously via two independent moieties. sCD4-17b was highly potent compared to the previously characterized broadly cross-reactive neutralizing monoclonal antibodies IgGb12, 2G12, and 2F5. Multiple primary isolates were neutralized, including two previously described as antibody resistant. Neutralization occurred for both R5 and X4 strains and was not restricted to clade B. However, several primary isolates were insensitive over the concentration range tested, despite the known presence of binding sites for both CD4 and 17b. sCD4-17b has potential utility for passive immunization against HIV-1 in several contexts, including maternal transmission, postexposure prophylaxis, and sexual transmission (topical microbicide).