Spike protein cleavage-activation and emergence of coronaviruses with extended tr

描述(申请人提供)：最近，基于一种感染人类的新型致命冠状病毒的出现和分离，冠状病毒引起了生物医学界的极大兴趣。这种病毒最近被命名为中东呼吸综合征(MERS)-CoV。像其他被包膜的病毒一样，冠状病毒通过膜融合进入它们的宿主细胞，这是一个由特定融合或病毒粒子上的“尖峰”蛋白介导的过程。这种病毒融合蛋白通常由宿主细胞蛋白酶激活。病毒基因组的突变可以导致棘突上的蛋白水解性裂解位点(S)的修饰，从而调节膜融合、病毒进入和宿主细胞的趋向性。我们已经确定了MERS冠状病毒尖峰蛋白裂解位点(S)的变化，这是它与其近亲以及大多数其他冠状病毒不同的地方。这些变化允许广泛表达的蛋白酶Furin对Spike蛋白的切割激活。呋喃类药物介导的激活是不寻常的，因为它发生在病毒进入期间。中东呼吸综合征冠状病毒以这种方式利用呋喃的能力可以解释该病毒的多变性及其作为人畜共患病冠状病毒的生命周期。在这个应用中，我们将与其近亲BatCoV-HKU4和BatCoV-HKU5比较MERS-CoV Spike的蛋白水解性切割位点，并确定Furin介导的切割在MERS-CoV多变性背景下的作用。更广泛地说，我们的目标是了解冠状病毒尖峰裂解位点的突变是如何调节蛋白酶切割和融合激活的。我们的工作将有助于公共卫生规划和测试使用呋喃类抑制剂作为MERS样冠状病毒感染的抗病毒治疗药物的可行性。

DESCRIPTION (provided by applicant): Recently, coronaviruses have generated substantial interest from the biomedical community based on the emergence and isolation of a novel and deadly coronavirus infecting humans. This virus was recently named Middle East Respiratory Syndrome (MERS)-CoV. Like other enveloped viruses, coronaviruses access their host cells by membrane fusion, a process mediated by a specific fusion, or "spike" protein on the virion. Such viral fusion proteins are often activated by host cell proteases. Mutations in the virus genome can lead to modifications to the proteolytic cleavage sites(s) on the spike that can subsequently regulate membrane fusion, virus entry and host cell tropism. We have identified changes in the MERS-CoV spike protein cleavage site(s) that distinguish it from its closest relatives, as well as most other coronaviruses. These changes allow cleavage-activation of the spike protein by furin, a broadly expressed protease. Furin-mediated activation is unusual in that it occurs during virus entry. The ability of MERS-CoV to utilize furin in this manner may explain the polytropic nature of the virus and its life cycle as a zoonotic coronavirus. In this application, we will characterize the proteolytic cleavage sites of MERS-CoV spike, in comparison to its closest relatives BatCoV- HKU4 and BatCoV-HKU5, and determine the role of furin-mediated cleavage in the context of the polytropic nature of MERS-CoV. More broadly, our goals are to understand how mutations in the CoV spike cleavage sites modulate protease cleavage and fusion activation. Our work will be useful for public health planning and in testing the feasibility of usng furin inhibitors as anti-viral therapeutics for MERS-like CoV infections.