Molecular mechanisms of host restriction of arenaviruses and viral antagonism

全球问题：病毒从其天然动物宿主溢出到人类的疾病很难预测。受几种环境、生物和生活方式因素的影响，新出现和再次出现的病毒感染在21世纪以越来越高的频率发生，特别是在缺乏有效措施预防和控制有可能发展为病毒大流行的流行病的情况下。拉沙热等非病毒性出血热是西非和南美洲的地方病，被世界卫生组织列为需要采取紧急研究和发展措施的疾病。人类通过直接接触受感染的啮齿动物粪便或尿液、摄入受污染的食物或通过呼吸道接触啮齿动物排泄物传播，导致从轻度流感样综合征到严重和高度致命的出血性疾病等各种疾病。最近尼日利亚拉萨病毒(LASV)暴发频率的增加强调，这些病毒不应再被视为零星流行的原因。由于缺乏疫苗和有效的治疗，尼日利亚和其他流行国家的这些疫情对公共卫生和社会经济造成的巨大影响进一步加剧。背景：宿主保护过程，即细胞免疫和病毒复制之间的相互作用是病毒感染过程中疾病结局的关键决定因素；有效地抑制针对入侵病原体的第一道防御机制是LASV感染的标志。宿主限制因子是固有的抗病毒感染反应的蛋白质成分。这些蛋白质在有效抑制病毒进入、复制和离开宿主细胞的关键步骤中发挥作用。我首次证明了锌金属蛋白酶ZMPSTE24对病毒进入的限制，以及ZMPSTE24和另一个宿主限制因子家族-干扰素诱导的跨膜蛋白(IFITM)-的新的协同抑制活性。病毒进入是病毒宿主范围、有效感染特定细胞类型的能力和疾病结局的关键决定因素，因此，针对Arena病毒生命周期的这一步骤可能对病毒感染的控制产生重大影响。总体目标：我的研究将解决现有的知识空白，这些空白阻碍了对Arena病毒与人类宿主细胞相互作用的深入了解，以及寻找新的抗病毒治疗方案的迫切需要。我将定义ZMPSTE24和IFITM宿主因子抑制ArenaVirus进入的机制，揭开涉及这些宿主因子的ArenaVirus感染动力学的细节，并确定允许逃避这些宿主抑制压力的病毒生命周期适应。主要目标：1)确定ZMPSTE24和IFITM对细胞感染屏障结构的物理影响，即支撑ZMPSTE24和IFITM机制的膜；2)解释ArenaVirus蛋白质在克服ZMPSTE24-IFITM活性中的作用；以及3)揭示ZMPSTE24的抗病毒机制如何塑造ArenaVirus的生命周期，从而为靶向治疗策略开辟潜在的途径。这项研究以强大的初步数据为基础，得益于我的专业知识以及与其他阿拉伯病毒专家和生物物理化学家的密切合作。我还与尼日利亚的传染病流行病学家合作，因此，在未来，这项提案将致力于加快和整合以社区为重点的方法，通过在被确定为易受阿拉伯病毒爆发的地区的公众参与来预防未来的流行病。

The Global Issue: Disease emergence from viruses that spill-over to humans from their natural animal reservoir host is difficult to predict. Influenced by several environmental, biological and lifestyle factors, emerging and re-emerging viral infections are occurring with increasing frequency in the 21st century, particularly in the absence of effective measures to prevent and control epidemics that have the potential to develop into virus pandemics. Endemic to West Africa and South America, arenaviral haemorrhagic fevers, such as Lassa fever (LF), are on the priority list of the World Health Organisation (WHO) as diseases requiring urgent research and development measures. Human transmission occurs through direct skin contact with infected rodent faeces or urine, ingestion of contaminated food, or through respiratory exposure to rodent excreta, resulting in illnesses ranging from mild flu-like syndromes to severe and highly fatal haemorrhagic diseases. Recent increased frequency of outbreaks in Nigeria of Lassa virus (LASV) has emphasised that these viruses should no longer be treated as causes of sporadic epidemics. The immense public health and socio-economic impact of these outbreaks in Nigeria and other endemic countries is further exacerbated by the lack of vaccines and effective treatments. Background: The interplay between host protective processes, i.e. cellular immunity, and viral replication is a key determinant of disease outcome during arenavirus infection; with potent suppression of the first line of defence mechanisms against invading pathogens being a hallmark of LASV infection. Host restriction factors are protein components of the intrinsic anti-viral response to infection. These proteins act at crucial steps to potently inhibit viral entry, replication and exit from the host cell. I have for the first time demonstrated a restriction of virus entry by the zinc metalloprotease, ZMPSTE24 and a novel synergistic inhibitory activity by ZMPSTE24 and another host restriction factor family - the interferon-induced transmembrane proteins (IFITMs). Virus entry is a key determinant of viral host range, of the ability to productively infect particular cell types, and of disease outcome, hence, targeting this step of the arenavirus lifecycle could have significant impact on the control of viral infection.Overarching aim: My research will address the existing knowledge gaps that hamper a deeper understanding of arenavirus interactions with human host cells and the urgent need to identify novel anti-viral therapeutic options. I will define the mechanisms of the ZMPSTE24 and IFITM host factors that inhibit arenavirus entry, unravel details of arenavirus infection dynamics that involve these host factors and determine the virus life cycle adaptations that allow escape from these host inhibition pressures. Key Objectives: 1) Determine the physical effects that ZMPSTE24 and IFITMs have on the structure of the cell's barriers to infection, i.e. membranes, that underpin the mechanism of ZMPSTE24 and IFITMs, 2) Explain the role of arenavirus proteins in overcoming ZMPSTE24-IFITM activity, and 3) Reveal how the antiviral mechanisms of ZMPSTE24 shape the arenavirus life cycle, thus opening up potential avenues for targeted therapeutic strategies.Altogether, this study will identify and characterise the processes that are modulated by arenaviruses, thus providing key information for the development of specific and effective antivirals, in the longer term. This research is underpinned by strong preliminary data and benefits from my expertise and strong collaborations with other arenavirus experts and biophysical chemists. I also collaborate with infectious disease epidemiologists in Nigeria, hence in the future, this proposal will aim to accelerate and integrate community-focused approaches to prevent future epidemics through public engagement in regions identified as vulnerable to arenavirus outbreaks.