Structural characterisation of the calicivirus entry pathway and its role in defining virulence

杯状病毒进入途径的结构特征及其在确定毒力中的作用

• 批准号: BB/T002239/1
• 负责人: Margaret Hosie
• 金额: $ 108.06万
• 依托单位: University of Glasgow
• 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=BB%2FT002239%2F1
• 关键词: Structural; characterisation; calicivirus; entry; pathway

Caliciviruses are a family of viruses that cause diseases of global importance to human and veterinary medicine alike. Most notable of the human caliciviruses is the human norovirus, a virus that causes ~685 million cases of acute gastroenteritis each year worldwide; ~200 million cases are in children under 5 years, leading to 70,000-200,000 child deaths/year, mostly in developing countries. Every year human caliciviruses are estimated to cost ~$60 billion worldwide related to healthcare costs and lost productivity.Caliciviruses of animals cause severe diseases, often with high morbidity and mortality, from usually fatal haemorrhagic disease in rabbits, enteritis in cattle to an acute respiratory disease in felids. While vaccines have been developed for the rabbit and feline caliciviruses, it is striking that the development of human caliciviral vaccines has lagged behind that of the animal caliciviruses. The host factors that affect calicivirus virulence remain to be identified and the pathogenesis of infection is poorly understood, although it is evident that viral evolution in both human and veterinary caliciviruses leads to the emergence of new variants. Ultrastructural studies of human caliciviruses had been hampered for many years by the lack of suitable systems for the large-scale in vitro propagation of the viruses. Although recent breakthrough studies have revealed that several genotypes of human norovirus can be grown in human intestinal enteroids derived from stem cells, it is still not possible to prepare the high titres of the human viruses in vitro that are required for detailed structural studies. Elucidating the structural and biochemical properties of caliciviruses will play a key role in the structure-based design of therapeutics and will inform the development of novel caliciviral vaccines to impact health. Accordingly, we elected to analyse at atomic resolution the feline calicivirus (FCV) as a representative pathogenic calicivirus. We examined the early stage of calicivirus entry and infection, discovering that when the virus binds its receptor, a funnel-shaped structure forms on viral shell that likely allows the virus to initiate infection. In parallel with this discovery, we observed that emerging virulent FCV strains appear to bypass entry steps that are essential for infection with strains that cause respiratory disease; infection of cells with these and vaccine strains can be blocked by chloroquine, unlike virulent isolates. This project brings together these two strands of research to examine the calicivirus-host interaction in avirulent and virulent strains of virus, comparing the two biological phenotypes and elucidating whether there are common structural determinants of caliciviral virulence. We will determine whether the novel structure observed in FCV is common to other caliciviruses by examining murine norovirus. The structure and function of the funnel-shaped structure observed on virions following receptor engagement will be modelled using lipid membranes to mimic viral uncoating and initiation of infection, enabling us to identify host-virus interactions that are critical for caliciviral entry. We will compare the early entry requirements of a panel of pathogenic strains of calicivirus isolated from an outbreak of virulent systemic disease in felids, investigating the role that the viral entry process plays in determining viral pathogenicity. Chimaeric viruses will be generated to identify regions in the caliciviral capsid that confer the virulent phenotype. This project will reveal fundamental insights into the early stages of infection with caliciviruses of humans and animals, facilitating structure-based approaches to the design of novel therapeutics and vaccines that will have a significant impact on human and animal health.

杯状病毒是一类病毒，会引起对人类和兽医都具有全球重要性的疾病。最值得注意的人类杯状病毒是人类诺沃克病毒，这种病毒每年在全世界造成约6.85亿例急性胃肠炎；约2亿病例发生在5岁以下儿童中，每年导致70,000-200,000名儿童死亡，其中大部分在发展中国家。据估计，每年人类杯状病毒在全球范围内造成约600亿美元的医疗成本和生产力损失。动物杯状病毒导致严重的疾病，通常具有高发病率和死亡率，从通常致命的兔子出血性疾病，牛的肠炎到猫的急性呼吸道疾病。虽然已经开发出针对兔和猫杯状病毒的疫苗，但令人惊讶的是，人类杯状病毒疫苗的开发落后于动物杯状病毒。影响杯状病毒毒力的宿主因素仍有待确定，感染的发病机制尚不清楚，尽管很明显，人类和兽用杯状病毒的病毒进化导致了新变种的出现。多年来，由于缺乏适合大规模体外繁殖的系统，人类杯状病毒的超微结构研究一直受到阻碍。尽管最近的突破性研究表明，几种类型的人诺沃克病毒可以在干细胞来源的人肠道小体中生长，但仍然不可能在体外制备详细结构研究所需的高滴度的人病毒。阐明杯状病毒的结构和生化特性将在基于结构的治疗设计中发挥关键作用，并将为开发影响健康的新型杯状病毒疫苗提供信息。因此，我们选择以原子分辨率分析猫杯状病毒(FCV)作为一种代表性的致病杯状病毒。我们研究了杯状病毒进入和感染的早期阶段，发现当病毒与其受体结合时，病毒壳上会形成一个漏斗状的结构，这可能允许病毒启动感染。与这一发现同时，我们观察到，新出现的强毒FCV菌株似乎绕过了感染导致呼吸道疾病的菌株所必需的进入步骤；与强毒菌株不同，这些菌株和疫苗菌株对细胞的感染可以被氯喹阻断。本项目将这两个研究链结合在一起，研究杯状病毒与宿主的相互作用，比较两种生物学表型，并阐明是否存在杯状病毒毒力的共同结构决定因素。我们将通过检测小鼠诺如病毒来确定在FCV中观察到的新结构是否与其他杯状病毒相同。在受体结合后在病毒粒子上观察到的漏斗状结构的结构和功能将被用脂膜来模拟病毒的脱壳和感染的开始，使我们能够识别对杯状病毒进入至关重要的宿主-病毒相互作用。我们将比较一组从猫类致命系统性疾病爆发中分离出来的杯状病毒致病株的早期进入要求，调查病毒进入过程在确定病毒致病性方面所起的作用。将产生嵌合病毒，以识别杯状病毒衣壳中赋予强毒表型的区域。该项目将揭示对人和动物杯状病毒感染早期阶段的基本见解，促进基于结构的方法来设计将对人类和动物健康产生重大影响的新疗法和疫苗。

项目成果

Modified-Live Feline Calicivirus Vaccination Reduces Viral RNA Loads, Duration of RNAemia, and the Severity of Clinical Signs after Heterologous Feline Calicivirus Challenge.

• DOI: 10.3390/v13081505
• 发表时间: 2021-07-30
• 期刊: Viruses
• 作者: Spiri AM;Riond B;Stirn M;Novacco M;Meli ML;Boretti FS;Herbert I;Hosie MJ;Hofmann-Lehmann R
• 通讯作者: Hofmann-Lehmann R

Calicivirus Infection in Cats.

• DOI: 10.3390/v14050937
• 发表时间: 2022-04-29
• 期刊: Viruses