Single-Chain Soluble BG505.SOSIP gp140 Trimers as Structural and Antigenic Mimics of Mature Closed HIV-1 Env
Single-Chain Soluble BG505.SOSIP gp140 Trimers as Structural and Antigenic Mimics of Mature Closed HIV-1 Env
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DOI：
10.1128/jvi.03451-14
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发表时间：
2015-05-01
影响因子：
5.4
通讯作者：
Kwong, Peter D.
中科院分区：
文献类型：
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作者：
Georgiev, Ivelin S.;Joyce, M. Gordon;Kwong, Peter D.
与其他I型融合机器类似，HIV-1包膜糖蛋白（Env）需要蛋白水解活化;具体而言，将gp 160前体裂解为gp 120和gp 41亚基，产生N-末端gp 41融合肽，并允许从未成熟的未裂解状态折叠为成熟的闭合状态。虽然HIV-1 Env裂解的原子水平结果仍在确定中，但未裂解状态与成熟闭合状态在抗原性上不同，据报道裂解对于可溶性Env模拟成熟病毒刺突是必需的。在这里，我们报告了当前最先进的可溶性Env模拟物BG505.SOSIP的重新设计，使其不依赖于切割。具体来说，我们用不同长度的Gly-Ser接头替换了gp 120和gp 41之间的弗林蛋白酶切割位点。所得到的连接的gp 120-gp 41构建体（称为单链gp 140（sc-gp 140））表现出不同水平的亲本裂解的BG 505.SOSIP的结构和抗原模拟。当构建体进行负选择，以消除亚种识别的中和抗体，高抗原模拟的BG505.SOSIP的三聚体可以获得负染色电子显微镜表明这些类似于成熟的封闭状态。在具有6个或更多个残基的接头的sc-gp 140中观察到更高比例的BG 505. SOSIP-三聚体模拟，其中15个残基的接头长度表现出特别有希望的性状。总的来说，灵活的链接之间的gp 120和gp 41在BG505.SOSIP，因此可以取代切割，和sc-gp 140的密切模仿疫苗优选的成熟封闭状态的Env.IMPORTANCEThe三聚体HIV-1包膜糖蛋白（Env）是唯一的目标病毒导向的中和抗体反应和疫苗设计的主要焦点。已证明获得Env的可溶性模拟物具有挑战性，并且认为其需要蛋白水解切割成双组分亚基gp 120和gp 41，以实现病毒体上成熟Env刺突的结构和抗原模拟。在这里，我们表明，替换gp 120和gp 41之间的切割位点在一个领先的可溶性gp 140构建体，BG505.SOSIP，与灵活的接头，可以导致分子，不需要切割折叠有效地进入成熟的封闭状态。我们的研究结果提供了深入了解切割对HIV-1 Env折叠的影响。在某些情况下，如遗传免疫，优化的切割非依赖性可溶性gp 140构建体可能具有超过亲本BG505.SOSIP的效用，因为它们不需要弗林蛋白酶切割来实现病毒体上成熟Env刺突的模拟。
Similar to other type I fusion machines, the HIV-1 envelope glycoprotein (Env) requires proteolytic activation; specifically, cleavage of a gp160 precursor into gp120 and gp41 subunits creates an N-terminal gp41 fusion peptide and permits folding from an immature uncleaved state to a mature closed state. While the atomic-level consequences of cleavage for HIV-1 Env are still being determined, the uncleaved state is antigenically distinct from the mature closed state, and cleavage has been reported to be essential for mimicry of the mature viral spike by soluble versions of Env. Here we report the redesign of a current state-of-the-art soluble Env mimic, BG505.SOSIP, to make it cleavage independent. Specifically, we replaced the furin cleavage site between gp120 and gp41 with Gly-Ser linkers of various lengths. The resultant linked gp120-gp41 constructs, termed single-chain gp140 (sc-gp140), exhibited different levels of structural and antigenic mimicry of the parent cleaved BG505.SOSIP. When constructs were subjected to negative selection to remove subspecies recognized by poorly neutralizing antibodies, trimers of high antigenic mimicry of BG505.SOSIP could be obtained; negative-stain electron microscopy indicated these to resemble the mature closed state. Higher proportions of BG505.SOSIP-trimer mimicry were observed in sc-gp140s with linkers of 6 or more residues, with a linker length of 15 residues exhibiting especially promising traits. Overall, flexible linkages between gp120 and gp41 in BG505.SOSIP can thus substitute for cleavage, and sc-gp140s that closely mimicked the vaccine-preferred mature closed state of Env could be obtained.IMPORTANCEThe trimeric HIV-1 envelope glycoprotein (Env) is the sole target of virus-directed neutralizing antibody responses and a primary focus of vaccine design. Soluble mimics of Env have proven challenging to obtain and have been thought to require proteolytic cleavage into two-component subunits, gp120 and gp41, to achieve structural and antigenic mimicry of mature Env spikes on virions. Here we show that replacement of the cleavage site between gp120 and gp41 in a lead soluble gp140 construct, BG505.SOSIP, with flexible linkers can result in molecules that do not require cleavage to fold efficiently into the mature closed state. Our results provide insights into the impact of cleavage on HIV-1 Env folding. In some contexts such as genetic immunization, optimized cleavage-independent soluble gp140 constructs may have utility over the parental BG505.SOSIP, as they would not require furin cleavage to achieve mimicry of mature Env spikes on virions.