Essential ionic triggers for enveloped virus entry

有包膜病毒进入的基本离子触发因素

• 批准号: MR/T016159/1
• 负责人: John Barr
• 金额: $ 98.31万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FT016159%2F1
• 关键词: Essential; ionic; triggers; enveloped; virus

In order to cause disease, all viruses must gain entry to their target cells. A common way viruses do this is by hijacking a cellular system called the endocytic network, which is normally used by cells to take up nutrients from the external environment. This network consists of tiny compartments called endosomes and many viruses have evolved the ability to trick cells that they are useful cargos in order to enter the network, and thus gain entry to the cell. However, once a virus enters an endosome, it is faced with a problem; it is effectively trapped, and so the virus must escape from the endosome in order to start an infection. The aim of this proposal is to understand in detail how viruses are able to escape the endosomes, and this work is based on exciting new research findings from our laboratory. Viruses escape endosomes using specialised spike proteins that cover the virion exterior and cause a process called fusion. To cause fusion, these spikes interact with specific chemicals within endosomes and dramatically change shape. After changing shape, the fusion spikes interact with the endosomal membrane from the inside, and force this membrane to mix with the viral envelope. When these two membranes merge together, fusion has occurred and the viral genome is released into the cytoplasm to continue the viral replication cycle. In simple terms, the ability of these viral spikes to change shape is critical in order for a virus to cause fusion, to escape the endosome and thus to continue the infection process. Despite this critical role, the mechanism by which spikes change shape and then cause fusion is poorly understood. Highlighting this poor understanding, we recently showed for the first time that some viruses within an important class of viruses known as bunyaviruses (which include many haemorrhagic fever viruses and viruses that are transmitted by mosquitoes - an increasing risk in the UK due to global warming) require potassium ions (K+) to cause the spikes to change shape and produce fusion. This finding represents a critical and previously overlooked requirement of the fusion mechanism.This proposal describes a set of experiments that will first reveal whether the requirement for K+ is a general characteristic of other viruses within the broader bunyavirus group. Next, we will investigate whether any other ions within endosomes have the same effect as K+ during virus entry, and then use state-of-the-art cryo-electron microscopy and X-ray crystallography techniques to reveal the high-resolution structure of the spikes in the inactive (pre-fusion) and activated shapes. Finally, we will use a variety of genetic techniques to identify parts of the spikes that are critical for responding to the biochemical signals, and also for mediating the shape changes themselves. Taken together, these experiments will provide a major advance in the understanding of the fusion mechanism, revealing in high detail how spikes are able to respond to chemical signals within endosomes, to change shape and cause fusion. This information is required to provide an essential foundation on which to design strategies to block spike fusogenesis; drugs that can do this would prevent infection and disease.

为了引起疾病，所有病毒都必须进入它们的靶细胞。一种常见的方式是病毒通过劫持一个称为内吞网络的细胞系统，该系统通常被细胞用于从外部环境中吸收营养。这个网络由称为内体的微小隔间组成，许多病毒已经进化出欺骗细胞的能力，它们是有用的货物，以便进入网络，从而进入细胞。然而，一旦病毒进入内体，它就面临着一个问题;它被有效地捕获，因此病毒必须逃离内体才能开始感染。这项提案的目的是详细了解病毒如何能够逃脱内体，这项工作是基于我们实验室令人兴奋的新研究结果。病毒利用专门的刺突蛋白逃离核内体，刺突蛋白覆盖病毒体的外部，并引起一个称为融合的过程。为了引起融合，这些尖峰与内体内的特定化学物质相互作用并显著改变形状。在改变形状后，融合刺突从内部与内体膜相互作用，并迫使该膜与病毒包膜混合。当这两种膜融合在一起时，融合已经发生，病毒基因组被释放到细胞质中以继续病毒复制周期。简而言之，这些病毒刺突改变形状的能力对于病毒引起融合、逃离内体并因此继续感染过程至关重要。尽管这一关键作用，机制，尖峰改变形状，然后导致融合是知之甚少。为了强调这种理解不足，我们最近首次表明，一种重要的病毒类别中的一些病毒被称为布尼亚病毒（其中包括许多出血热病毒和蚊子传播的病毒-由于全球变暖，英国的风险越来越大）需要钾离子（K+）来导致尖峰改变形状并产生融合。这一发现代表了融合机制的一个关键且以前被忽视的要求。该提案描述了一组实验，这些实验将首先揭示对K+的要求是否是更广泛的布尼亚病毒组中其他病毒的一般特征。接下来，我们将研究内体中的任何其他离子是否在病毒进入期间具有与K+相同的作用，然后使用最先进的冷冻电子显微镜和X射线晶体学技术来揭示非活性（融合前）和活化形状中尖峰的高分辨率结构。最后，我们将使用各种遗传技术来识别对响应生化信号至关重要的尖峰部分，以及介导形状变化本身。总之，这些实验将为理解融合机制提供重大进展，详细揭示尖峰如何能够响应内体内的化学信号，改变形状并引起融合。需要这些信息来提供一个重要的基础，在此基础上设计策略来阻断刺突融合;可以做到这一点的药物将预防感染和疾病。

项目成果

Cellular endosomal potassium ion flux regulates arenavirus uncoating during virus entry

细胞内体钾离子流调节病毒进入过程中沙粒病毒脱壳

• DOI: 10.1101/2023.06.23.546275
• 发表时间: 2023
• 作者: Shaw A

Lymphocytic choriomeningitis arenavirus requires cellular COPI and AP-4 complexes for efficient virion production

• DOI: 10.1128/jvi.02006-23
• 发表时间: 2024-02-09
• 期刊: JOURNAL OF VIROLOGY
• 影响因子: 5.4
• 作者: Byford，Owen;Shaw，Amelia B.;Barr，John N.
• 通讯作者: Barr，John N.

Organisation of the orthobunyavirus tripodal spike and the structural changes induced by low pH and K + during entry

正布尼亚病毒三足刺突的组织以及进入过程中低 pH 和 K 诱导的结构变化

• DOI: 10.1101/2022.08.11.503604
• 发表时间: 2022
• 作者: Hover S

The Native Orthobunyavirus Ribonucleoprotein Possesses a Helical Architecture.

• DOI: 10.1128/mbio.01405-22
• 发表时间: 2022-08-30
• 期刊: mBio
• 影响因子: 6.4