Influence of RNA on icosahedral virus particle structure

RNA对二十面体病毒颗粒结构的影响

• 批准号: BB/Y005732/1
• 负责人: George Lomonossoff
• 金额: $ 70.64万
• 依托单位: John Innes Centre
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FY005732%2F1
• 关键词: Influence; RNA; icosahedral; virus; particle

Viruses are extremely successful pathogens that infect organisms of every type, including plants, animals (including humans), fungi, and bacteria of all types. They are essentially intracellular parasites that introduce their genetic material into host cells and subvert the normal cellular functions to make more copies of themselves. They are normally present in the environment in the form of virus particles in which the viral nucleic acid, either DNA or RNA, is surrounded by a shell made up of multiple copies of one or more type of protein subunit encoded by the virus genome. In some cases (enveloped viruses) they are further surrounded by a membrane of host origin. The purpose of the protein shell is to protect the delicate genetic information from the, often harsh, environment outside the cell and to enable the virus to successfully spread to other hosts. This often involves uptake and transmission by vectors, such as insects or fungi, and the nucleic acid must be able to survive this process. Once inside a susceptible host, the virus makes more copies of itself by undergoing a "replication cycle" that includes several stages: uncoating of the particles to release the viral genome, expression of viral genes, replication of the viral nucleic acid and the encapsidation of the newly synthesised nucleic acid into particles that are then released to infect further hosts. This is all a carefully choreographed process, with replication and encapsidation of the viral genome usually closely linked. The specific encapsidation of viral, as opposed to host, nucleic acid into infectious particles is a vital step in the replication cycle of viruses. The process must result in the formation of virus particles that protect the labile genetic material effectively. This has led to the identification of defined RNA sequence elements or "packaging signals" in RNA viruses. Such packaging signals have been envisaged as labelling the viral RNA so that it is effectively "barcoded" in such a way that it is specifically recognised from a mixture of cellular molecules by the coat protein subunits, thereby conferring encapsidation selectivity. However, our recent work has shown that selectivity of packaging is determined by replication of an RNA molecule within infected cells, with synthesis of the coat protein being tightly coupled to RNA replication. In such "replication factories" the viral RNA genome is not in competition with other, non-replicating RNAs, suggesting that "barcoding" may not be required selective packaging. Rather, they may be present to ensure that the incorporation of RNA into particles proceeds efficiently to produce fully infectious virions. We have also obtained evidence that the length of replicating RNA may control the architecture of the resulting particles.To determine the role of potential packaging signals in the context of a replicating RNA, we will use a vector, pEff, based on the plant virus, potato virus X (PVX), that simultaneously produces replicating RNA and the coat proteins within plants. This closely mimics the situation that occurs in vivo during a viral infection. We have recently shown that the replicating RNA from pEff can be encapsidated by the coat protein from different, unrelated viruses. Thus, pEff is an ideal system for examining the role of packaging signals in the context of viral replication. The effect of elimination, duplication or mutation of the packaging signals on the assembly and morphology of the particles will be examined to obtain a more complete understanding of the mechanism of virus assembly. These studies will not only lead to a greater understanding of a critical stage of the viral replication cycle but will also enable specific RNAs to be deliberately packaged in capsids of defined architecture for use in bionanotechnology and the creation of novel RNA delivery systems.

病毒是非常成功的病原体，可以感染各种类型的生物体，包括植物、动物（包括人类）、真菌和所有类型的细菌。它们本质上是细胞内寄生虫，将其遗传物质引入宿主细胞并破坏正常细胞功能以复制更多自身。它们通常以病毒颗粒的形式存在于环境中，其中病毒核酸（DNA或RNA）被由病毒基因组编码的一种或多种蛋白质亚基的多个拷贝组成的外壳包围。在某些情况下（包膜病毒），它们进一步被宿主来源的膜包围。蛋白质外壳的目的是保护脆弱的遗传信息免受细胞外通常恶劣的环境的影响，并使病毒能够成功传播到其他宿主。这通常涉及昆虫或真菌等载体的吸收和传播，并且核酸必须能够在这个过程中存活下来。一旦进入易感宿主体内，病毒就会通过经历“复制周期”来制造更多的自身副本，该“复制周期”包括几个阶段：脱去颗粒的包被以释放病毒基因组、病毒基因的表达、病毒核酸的复制以及病毒的衣壳化。将新合成的核酸转化为颗粒，然后释放以感染更多宿主。这都是一个精心设计的过程，病毒基因组的复制和衣壳化通常紧密相连。与宿主相反，病毒核酸被特异性包裹成传染性颗粒是病毒复制周期中的重要步骤。该过程必须形成有效保护不稳定遗传物质的病毒颗粒。这导致了RNA病毒中特定RNA序列元件或“包装信号”的鉴定。这种包装信号被设想为标记病毒RNA，从而使其被外壳蛋白亚基从细胞分子混合物中特异性识别的方式有效地“条形码化”，从而赋予衣壳化选择性。然而，我们最近的工作表明，包装的选择性是由受感染细胞内 RNA 分子的复制决定的，外壳蛋白的合成与 RNA 复制紧密耦合。在这样的“复制工厂”中，病毒RNA基因组不与其他非复制RNA竞争，这表明可能不需要选择性包装“条形码”。相反，它们的存在可能是为了确保 RNA 掺入颗粒的过程有效进行，从而产生完全感染性的病毒体。我们还获得了证据，表明复制 RNA 的长度可以控制所得颗粒的结构。为了确定复制 RNA 中潜在包装信号的作用，我们将使用基于植物病毒的载体 pEff，马铃薯 X 病毒 (PVX)，可在植物内同时产生复制 RNA 和外壳蛋白。这非常类似于病毒感染期间体内发生的情况。我们最近表明，来自 pEff 的复制 RNA 可以被来自不同、不相关病毒的外壳蛋白包裹。因此，pEff 是检查包装信号在病毒复制中的作用的理想系统。将检查包装信号的消除、复制或突变对颗粒的组装和形态的影响，以获得对病毒组装机制的更完整的理解。这些研究不仅可以加深对病毒复制周期关键阶段的了解，而且还可以将特定的 RNA 故意包装在具有明确结构的衣壳中，用于生物纳米技术和创建新型 RNA 递送系统。