Inhibitors of flaviviral proteases with non-classical binding mode

本项目的主要目的是发现黄病毒蛋白酶的抑制剂。特别感兴趣的是含有能够与催化丝氨酸形成共价相互作用的识别元素的化合物。同样重要的是，在该项目的第二个资助期内，将更加重视蛋白酶抑制剂的细胞活性。最近爆发的寨卡病毒感染进一步增加了发现和开发预防和治疗黄病毒感染的治疗药物的紧迫性。虽然寨卡病毒在过去几个月受到了公众的广泛关注，但它“只是”在登革热和西尼罗热等已经“确定”的黄病毒感染之外，又增加了一层疾病负担。从公共卫生的角度来看，开发疫苗显然是一项非常有吸引力的战略。然而，数十年来针对登革热病毒的疫苗工作（直到最近才产生了一种效果中等的疫苗）表明，这不是应对寨卡等以前未知或未得到充分关注的病原体意外暴发的可靠选择。因此，我们认为将黄病毒的蛋白酶（一种对所有黄病毒的复制至关重要的病毒特异性酶）作为治疗靶点是很有吸引力的，目的是寻找具有足够选择性和广谱活性的药物，如果可能的话，这些药物可能还包括未知或研究较少的黄病毒。虽然密切相关的丙型肝炎病毒的丝氨酸蛋白酶是一个被充分利用的药物靶点，但在登革热和西尼罗河病毒领域的类似努力往往仍然相当令人失望，制药行业因此降低了各自药物发现项目的优先级。与这些期望相反，当前项目的第一个资助期导致发现了强效登革热和西尼罗河病毒蛋白酶抑制剂，这些抑制剂也显示出在细胞培养中抑制病毒复制的活性。目前的续篇提案旨在建立在这一成功的基础上，并推进蛋白酶抑制剂的发现和表征，并改善其体外特征。将特别强调具有共价结合模式的化合物，同时具有合适的PK/ADME配置文件。同时，我们打算开发病毒蛋白酶活性的细胞内检测系统，以弥补生化和表型/抗病毒检测之间的差距。

The principal aim of this project is to discover inhibitors of flaviviral proteases. Of particular interest are compounds that contain recognition elements capable of forming a covalent interaction with the catalytic serine. Equally important, an increased emphasis will be laid on the cellular activity of the protease inhibitors during the second funding period of this project. The recent outbreak of Zika virus infections has further increased the urgency to discover and develop therapeutical agents for the prevention and treatment of flaviviral infections. While Zika has received considerable public attention in the past months, it represents "only" an additional layer of disease burden on top of the already "established" flaviviral infections such as dengue and West Nile fever. From a public health perspective, development of vaccines clearly represents a very attractive strategy. However, decades of vaccine work on dengue virus, which only recently resulted in a vaccine with moderate efficacy, have shown that this is not a reliable option to deal with unexpected outbreaks of previously unknown or underattended pathogens such as Zika. We therefore consider it attractive to pursue the protease of flaviviruses, a virus-specific enzyme that is essential for replication of all flaviviruses, as a therapeutic target, with the aim to find agents with sufficient selectivity and, if possible, broad-spectral activity that potentially also includes as-yet unknown or less studied flaviviruses. While the serine protease of the closely related hepatitis C virus is a well-exploited drug target, similar efforts in the dengue and West Nile virus field have often remained fairly disappointing, and the pharmaceutical industry has therefore decreased the priority of respective drug discovery projects. Against these expectations, the first funding period of the current project resulted in the discovery of highly potent dengue and West Nile virus protease inhibitors which also show activity against viral replication in cell culture. The present continuation proposal intends to build on this success and to press ahead with the discovery and characterization of protease inhibitors with an improved in-vitro profile. A particular emphasis will be laid on compounds with a covalent binding mode that, at the same time, possess a suitable PK/ADME profile. At the same time, we intend to develop intracellular assay systems for viral protease activity, in order to bridge the gap between biochemical and phenotypic/antiviral assays.