Development of a 3Mut-Apex-Stabilized Envelope Trimer That Expands HIV-1 Neutralization Breadth When Used To Boost Fusion Peptide-Directed Vaccine-Elicited Responses
Development of a 3Mut-Apex-Stabilized Envelope Trimer That Expands HIV-1 Neutralization Breadth When Used To Boost Fusion Peptide-Directed Vaccine-Elicited Responses
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DOI：
10.1128/jvi.00074-20
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发表时间：
2020-07-01
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：
Chuang, Gwo-Yu;Lal, Yen-Ting;Kwong, Peter D.
HIV-1包膜（Env）三聚体，稳定在融合前闭合构象，可以引发能够中和HIV-1毒株的体液应答，这些HIV-1毒株在序列上与免疫毒株密切匹配。增加引发的中和宽度的一种策略涉及针对易感性靶位点的免疫应答的疫苗引发，然后用融合前封闭的Env三聚体疫苗加强这些应答。该策略已成功地在融合肽（FP）位点的脆弱性，在标准疫苗测试动物中引发交叉进化枝中和反应。然而，所引起的反应的广度和效力并不理想。在这里，我们鉴定了三个突变（3 mut），Met 302、Leu 320和Pro329，其将Env三聚体的顶点稳定在融合前闭合构象中，并且在抗原性、结构和免疫原性上显示了将3 mut与其他方法（例如，修复和稳定以及甘氨酸-螺旋断裂）产生能够提高FP-定向应答的宽度的表现良好的进化枝C-Env三聚体。这些三聚体的晶体结构证实了由Met 302和Leu 320贡献的疏水补丁稳定的融合前闭合的顶点，其中Pro329假设正则限制的二面角。我们用第二最普遍的FP 8序列（FP 8v 2，AVGLGAVF）取代这些三聚体的FP的N-末端8个残基（FP 8，残基512至519），并观察到用FP 8v 2的3 mutstabilized共有进化枝C-Env三聚体增强在豚鼠中由含有最普遍的FP 8序列（FP 8v 1，AVGIGAVF）的免疫原诱导的FP定向应答的广度。总的来说，3 mut可以稳定的Env三聚体的顶点，和所得的顶点稳定的Env三聚体可用于扩大的中和宽度引起对FP网站的vulnerability.IMPORTANCE一个主要的障碍，有效的HIV-1疫苗的发展是一个能够中和循环株的HIV，这是非常多样化的序列，往往是高度耐中和血清反应的启发。最近，我们展示了如何在标准疫苗测试动物中通过用HIV-1融合肽（FP 8）的最普遍的N-末端8个残基引发，然后用稳定的BG 505-包膜（Env）三聚体加强来引发具有20至30%中和宽度的血清。在这里，我们表明，随后用3 mut-apex-稳定的共有C-Env三聚体加强，修饰为具有第二最普遍的FP 8序列，比用稳定的BG 505-Env三聚体继续加强诱导的中和宽度更高。通过用含有第二最普遍的FP 8序列的异源三聚体加强引起的中和宽度增加，融合肽导向的免疫聚焦方法向实现有效的HIV-1疫苗方案更近了一步。
HIV-1 envelope (Env) trimers, stabilized in a prefusion-closed conformation, can elicit humoral responses capable of neutralizing HIV-1 strains closely matched in sequence to the immunizing strain. One strategy to increase elicited neutralization breadth involves vaccine priming of immune responses against a target site of vulnerability, followed by vaccine boosting of these responses with prefusion-closed Env trimers. This strategy has succeeded at the fusion peptide (FP) site of vulnerability in eliciting cross-clade neutralizing responses in standard vaccine-test animals. However, the breadth and potency of the elicited responses have been less than optimal. Here, we identify three mutations (3mut), Met302, Leu320, and Pro329, that stabilize the apex of the Env trimer in a prefusion-closed conformation and show antigenically, structurally, and immunogenically that combining 3mut with other approaches (e.g., repair and stabilize and glycine-helix breaking) yields well-behaved clade C-Env trimers capable of boosting the breadth of FP-directed responses. Crystal structures of these trimers confirmed prefusion-closed apexes stabilized by hydrophobic patches contributed by Met302 and Leu320, with Pro329 assuming canonically restricted dihedral angles. We substituted the N-terminal eight residues of FP (FP8, residues 512 to 519) of these trimers with the second most prevalent FP8 sequence (FP8v2, AVGLGAVF) and observed a 3mutstabilized consensus clade C-Env trimer with FP8v2 to boost the breadth elicited in guinea pigs of FP-directed responses induced by immunogens containing the most prevalent FP8 sequence (FP8v1, AVGIGAVF). Overall, 3mut can stabilize the Env trimer apex, and the resultant apex-stabilized Env trimers can be used to expand the neutralization breadth elicited against the FP site of vulnerability.IMPORTANCE A major hurdle to the development of an effective HIV-1 vaccine is the elicitation of serum responses capable of neutralizing circulating strains of HIV, which are extraordinarily diverse in sequence and often highly neutralization resistant. Recently, we showed how sera with 20 to 30% neutralization breadth could, nevertheless, be elicited in standard vaccine test animals by priming with the most prevalent N-terminal 8 residues of the HIV-1 fusion peptide (FP8), followed by boosting with a stabilized BG505-envelope (Env) trimer. Here, we show that subsequent boosting with a 3mut-apex-stabilized consensus C-Env trimer, modified to have the second most prevalent FP8 sequence, elicits higher neutralization breadth than that induced by continued boosting with the stabilized BG505-Env trimer. With increased neutralizing breadth elicited by boosting with a heterologous trimer containing the second most prevalent FP8 sequence, the fusion peptide-directed immune-focusing approach moves a step closer toward realizing an effective HIV-1 vaccine regimen.