Ringe Rajesh P, Ozorowski Gabriel, Rantalainen Kimmo, Struwe Weston B, Matthews Katie, Torres Jonathan L, Yasmeen Anila, Cottrell Christopher A, Ketas Thomas J, LaBranche Celia C, Montefiori David C, Cupo Albert, Crispin Max, Wilson Ian A, Ward Andrew B, Sanders Rogier W, Klasse P J, Moore John P
Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, USA.
Department of Integrative Structural and Computational Biology, International AIDS Vaccine Initiative Neutralizing Antibody Center and the Collaboration for AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, California, USA.
J Virol. 2017 Jul 12;91(15). doi: 10.1128/JVI.00677-17. Print 2017 Aug 1.
Native-like trimers of the SOSIP design are being developed as immunogens in human immunodeficiency virus type 1 (HIV-1) vaccine development programs. These trimers display the epitopes for multiple broadly neutralizing antibodies (bNAbs) but can also expose binding sites for some types of nonneutralizing antibodies (non-NAbs). Among the latter are epitopes in the gp120 V3 region that are highly immunogenic when SOSIP trimers are evaluated in animal models. It is presently uncertain whether antibodies against V3 can interfere with the induction of NAbs, but there are good arguments in favor of suppressing such "off-target" immune responses. Accordingly, we have assessed how to minimize the exposure of V3 non-NAb epitopes and thereby reduce their immunogenicity by introducing -glycans within the V3 region of BG505 SOSIP trimers. We found that inserting glycans at positions 306 and 314 (termed M1 and M7) markedly reduced V3 antigenicity while improving the presentation of trimer apex bNAb epitopes. Both added glycans were shown to be predominantly of the ManGlcNAc form. The additional introduction of the E64K ground-state stabilizing substitution markedly reduced or ablated soluble CD4 (sCD4) induction of non-NAb epitopes in V3 and/or associated with the coreceptor binding site. When a V3 glycan- and E64K-modified trimer variant, BG505 SOSIP.664-E64K.M1M7, was tested in rabbits, V3 immunogenicity was eliminated while the autologous NAb response was unchanged. Trimeric proteins are being developed for future HIV-1 vaccine trials in humans, with the goal of eliciting broadly active neutralizing antibodies (NAbs) that are active against a wide variety of circulating strains. In animal models, the present generation of native-like trimer immunogens, exemplified by the BG505 SOSIP.664 construct, induces narrow-specificity antibodies against the neutralization-resistant (tier-2), sequence-matched virus and more broadly active antibodies against sequence-divergent atypically neutralization-sensitive (tier-1) viruses. A concern in the trimer immunogen design field has been whether the latter off-target antibodies might interfere with the induction of the more desired responses to tier-2 epitopes. Here, we have inserted two glycans into the dominant site for tier-1 NAbs, the gp120 V3 region, to block the induction of off-target antibodies. We characterized the new trimers, tested them as immunogens in rabbits, and found that the blocking glycans eliminated the induction of tier-1 NAbs to V3-epitopes.
在人类免疫缺陷病毒1型（HIV-1）疫苗研发项目中，正在开发SOSIP设计的类天然三聚体作为免疫原。这些三聚体展示了多种广谱中和抗体（bNAb）的表位，但也可能暴露某些类型非中和抗体（non-NAb）的结合位点。后者包括gp120 V3区域中的表位，当在动物模型中评估SOSIP三聚体时，这些表位具有高度免疫原性。目前尚不确定针对V3的抗体是否会干扰NAb的诱导，但有充分理由支持抑制这种“脱靶”免疫反应。因此，我们评估了如何通过在BG505 SOSIP三聚体的V3区域内引入聚糖来最小化V3 non-NAb表位的暴露，从而降低其免疫原性。我们发现，在306和314位插入聚糖（称为M1和M7）可显著降低V3抗原性，同时改善三聚体顶端bNAb表位的呈现。两种添加的聚糖均显示主要为ManGlcNAc形式。额外引入E64K基态稳定取代可显著降低或消除V3中non-NAb表位和/或与共受体结合位点相关的可溶性CD4（sCD4）诱导。当在兔子中测试V3聚糖和E64K修饰的三聚体变体BG505 SOSIP.664-E64K.M1M7时，V3免疫原性被消除，而自身NAb反应未改变。正在开发三聚体蛋白用于未来人类的HIV-1疫苗试验，目标是诱导出对多种流行毒株具有活性的广谱活性中和抗体（NAb）。在动物模型中，以BG505 SOSIP.664构建体为代表的新一代类天然三聚体免疫原可诱导针对中和抗性（2级）、序列匹配病毒的窄特异性抗体以及针对序列不同的非典型中和敏感（1级）病毒的更广泛活性抗体。三聚体免疫原设计领域的一个担忧是，后者的脱靶抗体是否会干扰对2级表位更理想反应的诱导。在这里，我们在1级NAb的主要位点gp120 V3区域插入了两种聚糖，以阻断脱靶抗体的诱导。我们对新的三聚体进行了表征，在兔子中作为免疫原对它们进行了测试，发现阻断聚糖消除了对V3表位的1级NAb诱导。
