Development of novel protease inhibitors for influenza and paramyxoviruses

 描述(申请人提供)：许多被包裹的病毒的融合蛋白通过蛋白水解性启动步骤被激活。启动事件利用宿主细胞蛋白酶在包膜(融合)蛋白中进行特定的切割，通常在融合肽的附近。融合多肽的暴露是病毒进入过程的关键部分，如果没有蛋白水解性启动，病毒感染就无法启动。尽管蛋白酶是许多疾病的重要药物靶点，但针对参与病毒进入的宿主细胞蛋白酶的靶点却鲜有人关注。宿主细胞的蛋白水解酶通常受到严格的调节，宿主有 进化出高度特异的抑制物，对其天然蛋白酶具有很高的亲和力。我们建议 利用这种天然抑制物作为针对宿主的流感和其他呼吸道病毒的治疗方法。在病毒感染的情况下，很明显，在人类的情况下，启动不是通过单一的蛋白酶发生的，而是通过在给定组织中表达的相关蛋白酶的子集来进行的。因此，一种单一的天然(或修饰天然)抑制剂具有某种程度的广泛特异性，很可能是一种可行的抗病毒疗法。由于几个病毒家族可能共享相同或重叠的激活蛋白水解酶，单一的抑制物也可能对不同家族的病毒子集具有活性。我们最近开发了一种库尼茨类型的蛋白酶抑制剂(SPINT2或HAI-2)，作为治疗流行性和大流行性流感以及包括副粘病毒在内的其他包膜病毒的主要治疗药物。我们的重点将是甲型和乙型流感病毒，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中表征我们的主要候选抑制物，包括原代呼吸道细胞，并开发具有更高效力的工程衍生物。鉴于许多病毒是由宿主细胞蛋白酶激活的，我们认为这是一种谨慎的策略，我们的最终目标是开发一种可用于治疗多种感染性病原体的系统。

 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.