An RNA-targeted platform for anti-flavivirus drug discovery

摘要 新出现和重新出现的蚊媒黄病毒导致广泛的死亡、发病和经济负担。预防和治疗蚊媒黄病毒的选择有限：黄病毒疫苗面临独特的开发挑战，没有可用的抗病毒疗法，而且蚊媒已被证明难以根除。尽管有针对黄热病和日本脑炎病毒的疫苗，但这两种黄病毒每年仍导致超过 75,000 人死亡。世界上一半的人口面临登革热病毒 (DENV) 感染的风险，而包括寨卡病毒在内的新出现的黄病毒对公共卫生构成了重大挑战。 RNA 是小分子药物发现的一个引人注目的目标，而 RNA 病毒（例如黄病毒）的基因组包含高度保守的可靶向结构。多种天然产物以核糖体 RNA 为靶点，为 RNA 作为药物靶点建立了概念证明；然而，RNA 靶向药物发现仍然是一个新兴领域。最近已证明 DENV RNA 基因组中的特定三级结构对于病毒复制至关重要。这些结构在蚊媒黄病毒中高度保守，干扰其形成会抑制包装和复制，这表明破坏这些 RNA 基序的小分子将具有广谱抗黄病毒活性。 在 Ribometrix，我们的先导发现平台将非常快速和高通量的初始筛选与基于 SHAPE 技术（RNA 结构分析的黄金标准）的二次测定相结合。我们计划应用我们的平台来识别具有良好药物化学特性的小分子，这些小分子可以结合并破坏基本 DENV RNA 基序的结构。这些先导化合物将作为二期项目中开发抗 DENV 和广谱抗黄病毒疗法的基础。 RNA 具有大致相似的整体特性，因此允许在单一情况下有效靶向 RNA 的策略可能会允许靶向多种治疗上重要的 RNA。 Ribometrix 的长期愿景是应用该平台技术来发现针对尚无批准疗法的适应症的功能性 RNA 结构的小分子疗法。通过这项研究，我们将为 RNA 靶向配体发现的有效且通用的方法建立原理验证。

SUMMARY Emerging and re-emerging mosquito-borne flaviviruses cause widespread mortality, morbidity, and economic burden. Options for prevention and treatment of mosquito-borne flaviviruses are limited: Flavivirus vaccines face unique development challenges, no antiviral therapies are available, and the mosquito vectors have proven difficult to eradicate. Despite vaccines against Yellow Fever and Japanese encephalitis viruses, these two flaviviruses together cause more than 75,000 deaths each year. Half of the world’s population is at risk of Dengue virus (DENV) infection, and emerging flaviviruses, including the Zika virus, pose significant public health challenges. RNA is a compelling target for small-molecule drug discovery, and the genomes of RNA viruses, such as flaviviruses, contain highly conserved targetable structures. Multiple natural products target ribosomal RNA, establishing proof of concept for RNA as a drug target; however, RNA-targeted drug discovery remains a nascent field. Specific tertiary structures in the DENV RNA genome have recently been shown to be essential for viral replication. These structures are highly conserved across mosquito-borne flaviviruses and interfering with their formation inhibits packaging and replication, suggesting that small molecules that disrupt these RNA motifs will have broad-spectrum antiflaviviral activity. At Ribometrix, our lead discovery platform combines a very rapid and high-throughput initial screen with a secondary assay based on SHAPE technology, the gold standard for RNA structure analyses. We plan to apply our platform to identify small molecules with favorable medicinal chemistry properties that bind to and disrupt the structure of essential DENV RNA motifs. These lead compounds will serve as the foundation for the development of anti-DENV and broad-spectrum antiflaviviral therapies in a Phase 2 project. RNAs share broadly similar overall properties, so a strategy that allows RNA to be targeted efficiently in a single case will likely allow targeting of diverse therapeutically important RNAs. The long-term vision of Ribometrix is to apply this platform technology to discover small-molecule therapeutics that target functional RNA structures involved in indications for which there are no approved therapies. With this study, we will establish proof-of-principle for an efficient and generic approach for RNA-targeted ligand discovery.