Regulation of HIV-1 and Ebola virus replication by CpG dinucleotides, ZAP and TRIM25

人类免疫缺陷病毒I型(HIV-1)是一种逆转录病毒，其全球传播已导致获得性免疫缺陷综合征(AIDS)大流行。2016年，全球约有3700万艾滋病毒携带者，约180万新感染者，约100万人死于艾滋病相关疾病(http://www.unaids.org/en/resources/fact-sheet).总体而言，自艾滋病流行以来，已有约7600万人感染艾滋病毒，约3500万人死于与艾滋病有关的疾病。HIV-1主要感染CD4T细胞，当这些细胞死亡时，免疫系统受到损害，从而导致机会性感染和其他疾病，如癌症的发展。一旦一个人被感染，病毒就不能被消除，但它的复制可以用抗艾滋病毒药物来抑制。目前，已批准的抗艾滋病毒药物针对病毒复制周期的四个步骤，全球约有2100万人目前正在使用这些药物。这些药物可以无限期地控制感染，但不能治愈一个人。然而，艾滋病毒耐药株是一个日益严重的问题。因此，有必要继续开发新的抗艾滋病毒治疗方法。埃博拉病毒(EBOV)是一种高致病性病毒，可引起人类出血热，死亡率高达90%。2014-2016年西非疫情从几内亚农村蔓延到该国以及邻国利比里亚和塞拉利昂的主要人口中心，引发了全球紧急情况。到宣布疫情结束时，埃博拉病毒已经感染了28,000多人，并导致11,000多名(http://www.who.int/mediacentre/factsheets/fs103/en/).死亡尽管有很有希望的EBOV疫苗，但目前还没有针对感染者的有效疗法。因此，在细胞水平上研究病毒与宿主的相互作用对于开发新的EBOV治疗药物是至关重要的。EBOV的高死亡率需要在遏制级别4的实验室进行研究，这阻碍了对病毒复制方式的了解取得进展。然而，我们已经建立了一个安全的、非传染性的系统来分析埃博拉病毒的生物学。在这个提案中，我们将描述当人类细胞感知到病毒中的特定模式时，细胞蛋白如何抑制艾滋病毒-1和埃博拉病毒的复制。所有的RNA序列都有四个核苷酸碱基，包括病毒基因组：腺苷(A)、胞嘧啶(C)、鸟苷(G)和尿嘧啶(U)。病毒基因组中丰富的特定模式的RNA序列，C后面跟着G，已经被认为是人类细胞可以识别的，并抑制了病毒的复制。然而，尚不清楚这种CG模式是如何抑制病毒的。在这项资助中，我们将确定CG RNA序列如何与细胞蛋白质相互作用，以及这些蛋白质如何抑制病毒复制。特别是，我们将在安全、非传染性系统的背景下描述抗病毒蛋白ZAP和TRIM25如何抑制HIV-1和埃博拉病毒。

Human immunodeficiency virus type I (HIV-1) is a retrovirus whose worldwide spread has caused the acquired immune deficiency syndrome (AIDS) pandemic. In 2016, ~37 million people globally were living with HIV, ~1.8 million new people became infected and ~1 million people died from AIDS-related illnesses (http://www.unaids.org/en/resources/fact-sheet). Overall, ~76 million people have been infected with HIV since the epidemic started and ~35 million people have died from AIDS-related illnesses. HIV-1 primarily infects CD4 T cells and, when these cells die, the immune system is compromised allowing opportunistic infections and other diseases such as cancer to develop. Once a person is infected, the virus cannot be eliminated but its replication can be inhibited with anti-HIV drugs. Currently, there are approved anti-HIV drugs targeting four steps of the viral replication cycle and ~21 million people worldwide are currently accessing these drugs. These drugs can control the infection indefinitely, but do not cure a person. However, drug resistant strains of HIV are an increasing problem. Therefore, it is necessary to continue to develop new anti-HIV therapies.Ebola virus (EBOV) is a highly pathogenic virus that causes haemorrhagic fevers in humans with mortality rates up to 90%. The 2014-2016 West African epidemic caused a global emergency when it spread from rural Guinea to major population centres in that country and neighbouring Liberia and Sierra Leone. By the time the outbreak was declared over, EBOV had infected over 28,000 people and killed more than 11,000 (http://www.who.int/mediacentre/factsheets/fs103/en/). Although there are promising vaccines for EBOV, there is currently no effective therapy for an infected person. Therefore, studies of the virus-host interactions at the cellular level are essential for the development of novel EBOV therapeutics. The high mortality of EBOV necessitates its study in containment level 4 laboratories, which hampers progress in the understanding how the virus replicates. However, we have established a safe, non-infectious system to analyse Ebola virus biology.In this proposal, we will characterise how cellular proteins inhibit HIV-1 and Ebola virus replication when a specific pattern in the virus is sensed by a human cell. There are four nucleotide bases in all RNA sequences, including viral genomes: adenosine (A), cytosine (C), guanosine (G) and uracil (U). The abundance of a specific pattern of RNA sequence in a virus genome, C followed by a G, has been proposed to be recognised by the human cell and inhibits viral replication. However, it is unclear how this CG pattern inhibits the virus. In this grant, we will determine how the CG RNA sequence interacts with cellular proteins and how these proteins inhibit viral replication. In particular, we will characterise how the antiviral proteins ZAP and TRIM25 inhibit HIV-1 and Ebola virus in the context of the safe, non-infectious system.