Structural and dynamic traits underlying phenotypic variation in HIV-1 Env

我们很早就意识到 HIV-1 包膜糖蛋白 (Env) 中令人震惊的序列变异 基因，但这种多样性的结构和功能影响才刚刚开始被理解。结构性 环境变量的变化会影响其与病毒适应性和复制的所有关键驱动因素的相互作用，但这并不是 通过序列的变化捕获。这些差异是病毒表型特征的基础，例如中和作用 敏感性、向性、传染性和传播性。虽然最近的研究提供了详细的结构 来自一系列病毒分离株的三聚体 Env 胞外域的信息，该结构代表静态的、柏拉图式的 Env 组件的理想选择。在天然条件下，HIV Env 是一种高度动态的融合蛋白复合物， 可以在抗原性和功能性不同的构象状态之间闪烁。我们的生物物理学研究 小组和其他人正在提供第一个基于结构的迹象，表明 Env 经历的倾向 大规模的动态运动本质上是高度孤立特定的。这些变化直接影响给定的 Env 与宿主生物因子的相互作用。在这里我们将应用创新的结构分析 方法，包括结构质谱和冷冻电镜，来表征环境多样性并识别 结构变异和动力学对抗体结合和抗原呈递的影响 树突状细胞展示凝集素，DC-SIGN。我们开发了一种有效的方法来纯化类似天然的物质 SOSIP 三聚体来自高度不同的 HIV-1 分离株，初步研究表明三聚体 即使是中和抗性初级分离株在稳定性、局部结构方面也表现出显着差异 bNAb 表位的动力学、大规模构象呼吸和结构。我们将表征 来自中和层谱和全球小组的环境结构动态概况 抗性病毒，其组成高度代表循环中和表型。 我们将测试产生有利免疫反应（广度和效力）的变体是否表现出 结构动态特征。我们将评估动力学对抗体和 DC-SIGN 反应性的影响 不同的病毒分离株。对环境结构和功能变化的理解将为 了解艾滋病毒致病性和病毒适应性的差异，并更好地了解艾滋病病毒如何 免疫系统与这种极其可变的抗原作斗争。这些领域的进展将为我们提供信息 了解 HIV 进化，并可能有助于指导基于 Env 的疫苗和免疫原的开发。

We have long been aware of the astounding sequence variation in the HIV-1 envelope glycoprotein (Env) gene, but the structural and functional implications of this diversity are only beginning to be grasped. Structural variation in Env impacts its interactions with all key drivers of viral fitness and replication, and this is not captured by variation in sequence. These differences underlie viral phenotypic traits such as neutralization sensitivity, tropism, infectivity, and transmissibility. While recent studies have provided detailed structural information for trimeric Env ectodomain from a range of viral isolates, the structures represent a static, Platonic ideal of the Env assembly. Under native conditions, HIV Env is a highly dynamic fusion protein complex that can flicker between antigenically and functionally distinct conformational states. Biophysical studies from our group and others are providing the first structure-based indications that the propensity for Env to undergo large-scale dynamic movements is highly isolate-specific in nature. These changes directly impact a given Env's interactions with biological factors in the host. Here we will apply innovative structural analytical approaches, including structural mass spectrometry and cryo-EM, to characterize Env diversity and to identify the consequences of structural variation and dynamics on antibody binding and antigen presentation by the dendritic cell displayed lectin, DC-SIGN. We have developed an effective approach for purifying the native-like SOSIP trimers from highly divergent HIV-1 isolates and have demonstrated in preliminary studies that trimers even from neutralization resistant primary isolates exhibit significant differences in stability, local structural dynamics of bNAb epitopes, large-scale conformational breathing, and structure. We will characterize structural dynamic profiles of the Envs from across the neutralization Tier spectrum and from the Global Panel of resistant viruses, which was composed to be highly representative of circulating neutralization phenotypes. We will test whether variants that produced favorable immune responses (breadth and potency) exhibit structural dynamic traits. And we will assess the effect of dynamics on antibody and DC-SIGN reactivity for diverse viral isolates. An understanding of variation in Env structure and function will provide a foundation for understanding differences in HIV pathogenicity and viral fitness, and a better understanding of how the immune system grapples with this extremely variable antigen. Progress in these areas will inform our understanding of HIV evolution, and may help guide development of Env-based vaccines and immunogens.