Cyanovirin-N binds to gp120 to interfere with CD4-dependent human immunodeficiency virus type 1 virion binding, fusion, and infectivity but does not affect the CD4 binding site on gp120 or soluble CD4-induced conformational changes in gp120
Cyanovirin-N binds to gp120 to interfere with CD4-dependent human immunodeficiency virus type 1 virion binding, fusion, and infectivity but does not affect the CD4 binding site on gp120 or soluble CD4-induced conformational changes in gp120
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DOI：
10.1128/jvi.73.5.4360-4371.1999
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发表时间：
1999-05-01
影响因子：
5.4
通讯作者：
Lifson, JD
中科院分区：
文献类型：
--
作者：
Esser, MT;Mori, T;Lifson, JD
Cyanovirin-N（CV-N）是一种从蓝细菌Nostoc ellipsosporum中分离的11 kDa蛋白质，可有效灭活人类免疫缺陷病毒1型（HIV-1）、HIV-2和猿猴免疫缺陷病毒的不同毒株。虽然已经确定病毒表面包膜糖蛋白gp 120是CV-N的分子靶点，但详细的作用机制仍值得进一步研究。我们在一组测定病毒复制的试验中比较了匹配的天然和CVN处理的病毒制剂，评估了病毒生命周期的连续阶段。CV-N处理的病毒体未能感染细胞，如通过p24产生和HIV-1逆转录产物的定量PCR检测的，而靶细胞的处理没有阻断感染，证实CV-N作用于病毒水平，而不是靶细胞，以中止初始感染过程。与天然HIV-1制备物相比，CV-N处理的HIV-1病毒粒子显示与CD 4（+）T细胞的CD 4依赖性结合受损，并且不介导CD 4（+）靶细胞的“非融合”。CV-N还阻断HIV包膜糖蛋白Env诱导的CD 4依赖性细胞-细胞融合，用单克隆抗体（MAb）对HIV-1包膜糖蛋白上确定的表位进行的定位研究表明，CV-N与gp 120结合的方式不会封闭或改变由确定的MAb识别的gp 120上的CD 4结合位点或V3环或其他结构域，也不会干扰可溶性CD 4-诱导gp 120的构象变化，CV-N与可溶性gp 120或病毒体的结合抑制了随后独特的中和MAb 2G 12的结合，2G 12识别糖基化依赖性表位，然而，2G 12 MAb与gp 120的先前结合并不阻断CV-N随后的结合，这些结果有助于阐明CV-N的作用机制，并表明该化合物可能部分通过阻止包膜糖蛋白和靶细胞受体之间的基本相互作用而起作用，这一机制与CV-N对许多HIV分离株的广泛活性特征一致。1和其他慢病毒，并支持这种蛋白质作为杀微生物剂预防HIV性传播的潜在广泛用途。
Cyanovirin-N (CV-N), an 11-kDa protein isolated from the cyanobacterium Nostoc ellipsosporum, potently inactivates diverse strains of human immunodeficiency virus type 1 (HIV-1), HIV-2, and simian immunodeficiency virus. While it has been well established that the viral surface envelope glycoprotein gp120 is a molecular target of CV-N, the detailed mechanism of action is of further interest. We compared matched native and CVN-treated virus preparations in a panel of assays that measure viral replication, assessing successive stages of the viral life cycle. CV-N-treated virions failed to infect cells as detected by p24 production and quantitative PCR for HIV-1 reverse transcription products, whereas treatment of the target cells did not block infection, confirming that CV-N acts at the level of the virus, not the target cell, to abort the initial infection process. Compared to native HIV-1 preparations, CV-N-treated HIV-1 virions showed impaired CD4-dependent binding to CD4(+) T cells and did not mediate "fusion from without" of CD4(+) target cells. CV-N also blocked HIV envelope glycoprotein Env-induced, CD4-dependent cell-cell fusion, Mapping studies with monoclonal antibodies (MAbs) to defined epitopes on the HIV-1 envelope glycoprotein indicated that CV-N binds to gp120 in a manner that does not occlude or alter the CD4 binding site or V3 loop or other domains on gp120 recognized by defined MAbs and does not interfere with soluble CD4-induced conformational changes in gp120, Binding of CV-N to soluble gp120 or virions inhibited subsequent binding of the unique neutralizing MAb, 2G12, which recognizes a glycosylation-dependent epitope, However, prior binding of 2G12 MAb to gp120 did not block subsequent binding by CV-N, These results help clarify the mechanism of action of CV-N and suggest that the compound may act in part by preventing essential interactions between the envelope glycoprotein and target cell receptors, This proposed mechanism is consistent with the extensive activity profile of CV-N against numerous isolates of HIV-1 and other lentiviruses and supports the potential broad utility of this protein as a microbicide to prevent the sexual transmission of HIV.