Division of Oncology, Washington University School of Medicine, St. Louis, Missouri, USA.
McDonnell Genome Institute, Washington University School of Medicine, St. Louis, Missouri, USA.
J Virol. 2019 Apr 17;93(9). doi: 10.1128/JVI.00050-19. Print 2019 May 1.
Vicriviroc (VCV) is a CCR5 antagonist that blocks the viral entry of CCR5-tropic (R5) virions by binding to and inducing a conformational change in the chemokine receptor. Clinical resistance to CCR5 antagonists occurs in two phases, competitive and noncompetitive stages. In this study, we analyzed two subjects, from a phase 2b VCV clinical trial, whose quasispecies contained R5 and dual-mixed virions at the earliest recorded time of virological failure (VF). Genotypic analysis of R5-tropic patient-derived envelope genes revealed significant changes in the V1/V2 coding domain and convergence toward a more homogenous sequence under VCV therapy. Additionally, a small population of baseline clones sharing similar V1/V2 and V3 domains with the predominant VF isolate was observed. These clones were denoted preresistant based on their genotype. Preresistant clones and chimeric clones containing V1/V2 regions isolated during VF displayed high 50% inhibitory concentration (IC) values relative to those at baseline, consistent with early competitive resistance. Genotypic analysis of the dual-tropic clones also showed significant changes in the V1/V2 region, different from the resistant R5-tropic viruses. Our findings suggest that the V1/V2 domain plays a key role in the initial step of development of drug resistance. It is believed that each CCR5 antagonist-resistant isolate will develop its own unique set of mutations, making it difficult to identify a signature mutation that can effectively predict CCR5 antagonist resistance. This may explain why we do not observe shared mutations among clinical studies. The present study examined the earliest events in the development of drug resistance with viral quasispecies that continued the use of CCR5 for entry. Genotypic and phenotypic assays demonstrated a distinct role of the variable domain V1/V2 in competitive resistance to CCR5 antagonist therapy. Thus, future studies analyzing the development of clinical resistance should focus on the relationship between the V1/V2 and V3 domains.
维立西洛（VCV）是一种 CCR5 拮抗剂，通过与趋化因子受体结合并诱导其构象改变，从而阻断 CCR5 嗜性（R5）病毒进入细胞。对 CCR5 拮抗剂的临床耐药性分为两个阶段：竞争阶段和非竞争阶段。在这项研究中，我们分析了来自 VCV 临床 2b 期试验的两名患者，他们的准种在最早记录到病毒学失败（VF）的时间就同时含有 R5 和双混合病毒。对 R5 嗜性患者来源的包膜基因进行基因分型分析显示，在 VCV 治疗下，V1/V2 编码区发生显著变化，且向更同质的序列趋同。此外，在基线时观察到一小部分与主要 VF 分离株具有相似 V1/V2 和 V3 结构域的克隆，这些克隆被定义为预耐药。基于基因型，VF 期间分离的预耐药克隆和包含 V1/V2 区的嵌合克隆与基线相比，50%抑制浓度（IC）值较高，这与早期竞争耐药一致。双嗜性克隆的基因分型分析也显示 V1/V2 区发生显著变化，与耐药 R5 嗜性病毒不同。我们的研究结果表明，V1/V2 结构域在耐药发展的初始步骤中起着关键作用。人们认为，每种 CCR5 拮抗剂耐药分离株都会产生自己独特的突变集，这使得很难识别一个有效的特征性突变来有效预测 CCR5 拮抗剂耐药性。这可能解释了为什么我们在临床研究中没有观察到共同的突变。本研究使用继续使用 CCR5 进入细胞的病毒准种，检测了耐药性发展的最早事件。基因型和表型检测表明 V1/V2 可变区在 CCR5 拮抗剂治疗的竞争耐药中起着独特的作用。因此，未来分析临床耐药性发展的研究应集中在 V1/V2 和 V3 结构域之间的关系上。
