Variola Virus G1L:An Antiviral Drug Target

描述（由申请人提供）：天花病毒（天花）是a类病原体，被认为是用作生物恐怖主义制剂的最重大威胁之一。由于疫苗接种的并发症，禁止对民众进行大规模免疫接种。我们目前的研究旨在开发有效的抗正痘病毒药物，这被指定为高优先级生物防御项目。本研究以牛痘病毒（VV）为模型系统，目的是确定W编码的l7L半胱氨酸蛋白酶或G1L金属蛋白酶是否为痘病毒核心蛋白蛋白酶（vCPP），并利用该信息开发vCPP抑制剂作为候选抗病毒药物。我们最近已经证明l7L半胱氨酸蛋白酶是vCPP，并且正在进行针对该靶点的药物开发工作。但是G1L呢？这代表了一个意外的机会，应该加以调查。我们认为wg1l金属蛋白酶是一种独特的正痘病毒抗病毒靶点。本申请中概述的实验目的是：1)产生G1L条件致死突变体，以评估零突变体的表型；2)阐明G1L在病毒复制和/或组装过程中的生物学作用；3)验证和表征G1L基因产物的酶活性。这些实验的成功完成将使开发G1L金属蛋白酶抑制剂作为抗病毒药物成为可能。除了l7L外，还有几个重要的原因需要开发G1L靶点：并非所有的酶都具有同样的“可药物性”，G1L抑制剂可能具有更好的活性/特异性；当暴露于选择性压力时，病毒迅速获得耐药性，因此拥有多种抗病毒药物至关重要；使用多种抑制剂的鸡尾酒疗法可能比使用单一药物更有效。

DESCRIPTION (provided by applicant): Variola virus (Smallpox) is a Category A pathogen considered to be one of the most significant threats for use as a bioterrorism agent. Due to complications from vaccination, mass immunization of the populace is contra-indicated. Our current research seeks to develop effective anti-orthopoxvirus drug(s), which is designated as a high priority biodefense project. Using vaccinia virus (VV) as a model system, the goal of our previous research was to determine if the l7L cysteine proteinase or the G1L metalloproteinase encoded by W is the poxvirus core protein proteinase (vCPP), and to use this information to develop vCPP inhibitors as candidate antiviral drugs. We have recently demonstrated that the l7L cysteine proteinase is the vCPP and are proceeding with drug development efforts on this target. But what about G1L? This represents an unexpected opportunity that should be investigated. We believe that the W G1L metalloproteinase represents a unique and distinct orthopoxvirus antiviral target. The purpose of the experiments outlined in this application are to: 1) Produce a G1L conditional-lethal mutant to assess the phenotype of the null mutant; 2) Elucidate the biological role of G1L during viral replication and/or assembly; and 3) Demonstrate and characterize the enzymatic activity of the G1L gene product. Successful completion of these experiments should allow the development of G1L metalloproteinase inhibitors as antiviral drugs to be initiated. There are several important reasons to exploit the G1L target in addition to l7L: Not all enzymes are equally "drug-able" and G1L inhibitors may have superior activity/specificity profiles; When exposed to selective pressure, viruses rapidly acquire resistance so having multiple antiviral drugs available is essential; and using a cocktail approach with multiple inhibitors may be more effective than using a single drug.