Development of novel protease inhibitors for influenza and paramyxoviruses

 描述（由申请方提供）：许多包膜病毒的融合蛋白通过蛋白水解引发步骤活化。引发事件利用宿主细胞蛋白酶在包膜（融合）蛋白中进行特异性切割，通常在融合肽的紧邻处。融合肽的暴露是病毒进入过程的关键部分，并且在没有蛋白水解引发的情况下，不能启动病毒感染。虽然蛋白酶是许多疾病的重要药物靶标，但参与病毒进入的宿主细胞蛋白酶的靶向很少受到关注。宿主细胞蛋白酶通常处于严格调控下，并且宿主具有 进化出高度特异性的抑制剂，其对天然蛋白酶具有高亲和力。我们提出 利用这种天然抑制剂作为流感和其他呼吸道病毒的宿主靶向治疗方法。在病毒感染的情况下，很明显，在许多情况下，引发不是通过单一蛋白酶发生的，而是通过在给定组织中表达的相关蛋白酶的子集发生的。因此，具有一定程度的广泛特异性的单一天然（或修饰的天然）抑制剂可能是可行的抗病毒治疗剂。由于几个病毒家族可能共享相同或重叠的活化蛋白酶，因此单一抑制剂也可能对不同家族中的病毒子集具有活性。我们最近开发了一种库尼茨型蛋白酶抑制剂（SPINT 2或HAI-2），作为治疗流行性和大流行性流感以及其他包膜病毒（包括副粘病毒）的主要治疗药物。我们在该项目中的重点将是甲型和B型流感病毒，以及人类偏肺病毒和人类副流感病毒1。我们建议在体外和细胞培养（包括原代呼吸道细胞）中表征我们的主要候选抑制剂，并开发具有改进效力的工程衍生物。鉴于许多病毒是由宿主细胞蛋白酶激活的，我们认为这种策略是谨慎的，我们的最终目标是开发一种可用于治疗多种感染因子的系统。

 DESCRIPTION (provided by applicant): The fusion proteins of many enveloped viruses are activated by a proteolytic priming step. The priming event utilizes a host cell protease to make a specific cleavage in the envelope (fusion) protein, often in the immediate vicinity of the fusion peptide. Exposure of the fusion peptide is a critical part of the virus entry process, and without proteolytic priming, virus infection cannot be initiated. While proteases are important drug targets for many diseases, the targeting of host cell proteases involved in virus entry has received little attention. Host cell proteases are usually under tight regulation, and the host has evolved highly specific inhibitors, which have high affinity for their natural protease. We propose to take advantage of such natural inhibitors as a host-targeted therapeutic approach for influenza and other respiratory viruses. In the case of viral infection, it is apparent that in man cases priming is not occurring via a single protease, but rather via a sub-set of related proteases expressed in a given tissue. Thus a single natural (or modified-natural) inhibitor with some degree of broad specificity is likely to be a viable anti-viral therapeutic. As several virus families likely share the same or overlapping activating proteases, a single inhibitor is also likey to be active against a sub-set of viruses in distinct families. We have recently developed a kunitz-type protease inhibitor (SPINT2 or HAI-2) as a lead therapeutic for treatment of epidemic and pandemic influenza, as well as other enveloped viruses including paramyxoviruses. Our focus in the project will be influenza A and B viruses, as well as human metapneumovirus and human parainfluenza virus 1. We propose to characterize our lead candidate inhibitor, both in vitro and in cell culture, including primary respiratory tract cells, and to develop engineered derivates with improved potency. Given that many viruses are activated by host cell proteases, we feel this strategy is a prudent one, with our eventual goal being to develop a system that can be used to treat multiple infectious agents.