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Mechanism of action of an African swine fever virus virulence factor

非洲猪瘟病毒毒力因子的作用机制

基本信息

批准号：
BB/E019781/1
负责人：
Steve Goodbourn
金额：
$ 33.46万
依托单位：
St George's, University of London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FE019781%2F1
关键词：
Mechanism action African swine fever

项目摘要

African swine fever virus (ASFV) causes an economically important disease of pigs with high mortality rates. We plan to study one of the proteins (DP71L) encoded by the virus to determine its function in cells and the role it plays in causing disease in pigs. Previous work has shown that deleting the gene for this protein can reduce ASFV virulence in pigs. This protein is similar over part of its length to a Herpes simplex virus virulence factor, ICP34.5, and to a host protein (GADD34) which is induced by factors such as damage to DNA. We have recently shown that DP71L has two novel functions not demonstrated for ICP34.5 or GADD34. First it interferes with induction of interferon (IFN), which activates an important host anti-viral pathway. The mechanism by which it does this is not known. Secondly, DP71L stimulates a cellular enzyme, protein phosphatase 1 (PP1), also by an unknown mechanism. PP1 can be directed to activate or inhibit other cellular pathways by association with regulatory proteins. We propose that the DP71L protein acts as a regulator of PP1 to displace an inhibitor from PP1 and target the enzyme to modulate the activity of host cell pathways. This may be the mechanism by which DP71L inhibits induction of IFN. Our prediction is that DP71L may inhibit other cellular functions. Mutant forms of the DP71L protein will be made and used to study which parts of the protein are needed for each of its functions. We will also determine at which point DP71L blocks the IFN induction pathway and investigate if DP71L affects other host pathways. In particular we will study whether DP71L affects expression of other cellular genes, in addition to IFN, which are important for stimulating the host's response to infection. We will also study whether DP71L blocks two other host pathways which restrict virus replication. In these pathways the host cell either commits suicide (called apoptosis) or shuts-off translation of messenger RNAs to prevent virus from replicating. Deletion of the DP71L gene dramatically reduces virulence in pigs. By making recombinant virus which expresses mutant forms of the DP71L protein, we will determine if either or both functions of the protein are required for virulence. We will also determine if the functions we observe in isolated cells are also observed in infected pigs. The results will help us to understand more about the mechanisms by which IFN is induced, and the functions of PP1 and how this may be directed by viruses to avoid the host's defences. Understanding the role of individual proteins in virulence will assist in the rational development of an attenuated ASFV vaccine. Currently no vaccine is available so disease control relies on rapid diagnosis and implementation of quarantine and slaughter.

非洲猪瘟病毒（ASFV）是猪的一种重要的经济疾病，具有很高的死亡率。我们计划研究由该病毒编码的一种蛋白（DP71L），以确定其在细胞中的功能及其在猪的致病过程中所起的作用。先前的研究表明，删除该蛋白的基因可以降低猪的ASFV毒力。该蛋白在部分长度上与单纯疱疹病毒毒力因子ICP34.5和宿主蛋白GADD34相似，后者是由DNA损伤等因素诱导的。我们最近发现DP71L具有ICP34.5或GADD34没有的两个新功能。首先，它干扰干扰素（IFN）的诱导，干扰素激活了一个重要的宿主抗病毒途径。其作用机制尚不清楚。其次，DP71L刺激细胞酶，蛋白磷酸酶1 (PP1)，也是通过一种未知的机制。PP1可以通过与调节蛋白的结合来激活或抑制其他细胞通路。我们提出DP71L蛋白作为PP1的调节剂，取代PP1的抑制剂，并靶向酶来调节宿主细胞通路的活性。这可能是DP71L抑制IFN诱导的机制。我们的预测是DP71L可能抑制其他细胞功能。DP71L蛋白的突变形式将被制造出来，并用于研究该蛋白的哪些部分是其每种功能所必需的。我们还将确定DP71L在哪个点阻断IFN诱导途径，并研究DP71L是否影响其他宿主途径。特别是，我们将研究DP71L是否影响除了IFN之外的其他细胞基因的表达，这些基因对刺激宿主对感染的反应很重要。我们还将研究DP71L是否阻断了限制病毒复制的其他两种宿主途径。在这些途径中，宿主细胞要么自杀（称为凋亡），要么关闭信使rna的翻译以阻止病毒复制。DP71L基因的缺失显著降低了猪的毒力。通过制造表达DP71L蛋白突变形式的重组病毒，我们将确定该蛋白的一种或两种功能是否需要用于毒力。我们还将确定我们在分离细胞中观察到的功能是否也在感染猪中观察到。这些结果将帮助我们更多地了解IFN被诱导的机制，以及PP1的功能，以及它如何被病毒引导以避开宿主的防御。了解单个蛋白质在毒力中的作用将有助于合理研制ASFV减毒疫苗。目前没有疫苗可用，因此疾病控制依赖于快速诊断和实施检疫和屠宰。