Eggink Dirk, de Taeye Steven W, Bontjer Ilja, Klasse Per Johan, Langedijk Johannes P M, Berkhout Ben, Sanders Rogier W
Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center of the University of Amsterdam, Amsterdam, the Netherlands.
Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, USA.
J Virol. 2016 Nov 14;90(23):10587-10599. doi: 10.1128/JVI.01616-16. Print 2016 Dec 1.
The trimeric HIV-1 envelope glycoprotein spike (Env) mediates viral entry into cells by using a spring-loaded mechanism that allows for the controlled insertion of the Env fusion peptide into the target membrane, followed by membrane fusion. Env is the focus of vaccine research aimed at inducing protective immunity by antibodies as well as efforts to develop drugs that inhibit the viral entry process. The molecular factors contributing to Env stability and decay need to be understood better in order to optimally design vaccines and therapeutics. We generated viruses with resistance to VIR165, a peptidic inhibitor that binds the fusion peptide of the gp41 subunit and prevents its insertion into the target membrane. Interestingly, a number of escape viruses acquired substitutions in the C1 domain of the gp120 subunit (A60E, E64K, and H66R) that rendered these viruses dependent on the inhibitor. These viruses could infect target cells only when VIR165 was present after CD4 binding. Furthermore, the VIR165-dependent viruses were resistant to soluble CD4-induced Env destabilization and decay. These data suggest that VIR165-dependent Env proteins are kinetically trapped in the unliganded state and require the drug to negotiate CD4-induced conformational changes. These studies provide mechanistic insight into the action of the gp41 fusion peptide and its inhibitors and provide new ways to stabilize Env trimer vaccines.
Because of the rapid development of HIV-1 drug resistance, new drug targets need to be explored continuously. The fusion peptide of the envelope glycoprotein can be targeted by anchor inhibitors. Here we describe virus escape from the anchor inhibitor VIR165. Interestingly, some escape viruses became dependent on the inhibitor for cell entry. We show that the identified escape mutations stabilize the ground state of the envelope glycoprotein and should thus be useful in the design of stabilized envelope-based HIV vaccines.
三聚体HIV-1包膜糖蛋白刺突（Env）通过一种弹簧加载机制介导病毒进入细胞，该机制允许Env融合肽可控地插入靶膜，随后发生膜融合。Env是旨在通过抗体诱导保护性免疫的疫苗研究以及开发抑制病毒进入过程药物的努力的重点。为了优化疫苗和治疗方法的设计，需要更好地了解影响Env稳定性和衰变的分子因素。我们产生了对VIR165具有抗性的病毒，VIR165是一种肽类抑制剂，它结合gp41亚基的融合肽并阻止其插入靶膜。有趣的是，许多逃逸病毒在gp120亚基的C1结构域中获得了替代（A60E、E64K和H66R），这些替代使这些病毒依赖于该抑制剂。这些病毒只有在CD4结合后存在VIR165时才能感染靶细胞。此外，依赖VIR165的病毒对可溶性CD4诱导的Env去稳定化和衰变具有抗性。这些数据表明，依赖VIR165的Env蛋白在动力学上被困在未结合配体的状态，并且需要药物来应对CD4诱导的构象变化。这些研究为gp41融合肽及其抑制剂的作用提供了机制性见解，并为稳定Env三聚体疫苗提供了新方法。
由于HIV-1耐药性的快速发展，需要不断探索新的药物靶点。包膜糖蛋白的融合肽可以被锚定抑制剂靶向。在这里，我们描述了病毒从锚定抑制剂VIR165逃逸的情况。有趣的是，一些逃逸病毒在细胞进入时变得依赖于该抑制剂。我们表明，鉴定出的逃逸突变稳定了包膜糖蛋白的基态，因此在基于包膜的HIV疫苗设计中应该是有用的。
