Host Determinants Associated with Susceptibility to Respiratory Syncytial Virus (RSV) Infection

下呼吸道感染是低收入国家最常见的死亡原因，特别是新生儿和幼儿。呼吸道合胞病毒（RSV）是这一年龄组中最重要的呼吸道病原体，可引起广泛的呼吸道症状，从普通感冒到肺炎，通常是毛细支气管炎。它还与哮喘的发展有关。RSV是一种负链RNA病毒，属于副粘病毒家族，与麻疹、腮腺炎、副流感和风疹病毒有关。目前的预防和治疗选择非常有限，因此临床护理主要是支持性的。越来越多的证据表明，宿主基因组中的遗传基因多态性对许多传染病的易感性和严重程度的影响超过对任何其他类型疾病的影响。然而，已知的与传染病相关的遗传多态性非常少，而且迄今为止在全基因组关联研究（GWAS）中发现的遗传多态性仅占遗传性的一小部分。目标;本研究的目的是利用一种结合体外基因组筛选和临床遗传关联研究的新方法，鉴定功能特征的遗传生物标志物和遗传验证的RSV潜在药物靶点。本项目的具体目的是利用高通量体外基因组筛选表达RSV突变体的绿色荧光蛋白（GFP），通过RNA干扰鉴定影响RSV感染的细胞宿主因子。通过数据库（NHGRI）搜索（www.genome.gov/gwastudies/）确定这些影响RSV复制的宿主因子基因中已知的具有较小等位基因频率（MAF）为>0.05的疾病相关单核苷酸多态性（SNP）。通过使用低密度SNP阵列和定量聚合酶链反应（qPCR）对RSV感染者样本进行基因分型，检测这些影响RSV复制的SNP是否与RSV感染的严重程度相关。这些样本将由NHS洛锡安生物资源中心提供，该中心包含90000份呼吸道样本，对包括RSV在内的一系列呼吸道病毒进行了检测（已获得伦理批准）。将x线影像中的肺炎实变、RSV PCR、WBC、CRP、合并症、治疗、住院时间、疾病负担（DALY）等人口统计学和疾病相关参数与患者基因型相关联。这种方法的优势在于鉴定出功能有效的snp，而在其他（主要是GWAS）研究中鉴定出的绝大多数疾病相关snp（>14000）功能完全未知。因此，本研究不仅具有高度的相关性和较强的翻译影响，而且提供了一个原理证明。从先前使用不同病毒的研究中，我们有初步证据表明这种方法是可行的。该项目预计将对感染rsv的儿童和成人的临床管理和治疗产生重大影响。

Lower respiratory tract infections are the most frequent cause of mortality in low-income countries, in particular in newborns and in young children. Respiratory syncytial virus (RSV) which is the most important respiratory pathogen in this age group, causes a broad spectrum of respiratory symptoms from common cold to pneumonia and, typically, bronchiolitis. It is also associated with the development of asthma. RSV is a negative strand RNA virus that belongs to the family of Paramyxoviruses and is related to Measles, Mumps, Parainfluenza and Rubella virus. There are very limited prevention and treatment options at the moment, and clinical care is thus mainly supportive. Increasing evidence suggests that inherited genetic polymorphisms in the host genome affect susceptibility and severity in many infectious diseases, more than in any other types of diseases. However, only very few infectious disease-associated genetic polymorphisms are known, and those that have been identified so far in genome-wide-association studies (GWAS) only account for a small portion of heritability. Aims;The objective of this study is to identify functionally characterized genetic biomarkers and genetically validated potential drug targets for RSV using a new approach that combines a genomic in vitro screen with a clinical genetic association study. The specific aims of this project are To identify cellular host factors that affect RSV infection by RNA interference using a green fluorescent protein (GFP)-expressing RSV mutant in a high-throughput genomic in vitro screen.To identify known, disease-associated single nucleotide polymorphisms (SNPs) with a minor allele frequency (MAF) of >0.05 in these host factor genes that affect RSV replication by database (NHGRI) search (www.genome.gov/gwastudies/) To test if any of these SNPs that affect RSV replication correlate with the severity of RSV infection by genotyping samples from RSV-infected individuals using low density SNP arrays and quantitative polymerase chain reaction (qPCR). The samples will be provided from the NHS Lothian Bioresource which contains >90.000 respiratory specimen tested for a range (>10) of respiratory viruses including RSV (ethics approval provided). To correlate demographic and disease-related parameters such as pneumonic consolidation in x-ray imaging, RSV PCR, WBC, CRP, comorbitities, treatment, length of hospitalization, disease burden (DALY) etc. with the patient genotype.The advantage of this approach is the identification of functionally validated SNPs, in contrast to the vast majority of disease-associated SNPs (>14.000) that has been identified in other (mainly GWAS) studies whose function is completely unknown. Thus, this study is not only highly relevant and has strong translational impact, but also provides a proof-of-principle. From previous studies using a different virus we have preliminary evidence that the approach is feasible. The project is expected to have significant impact on clinical management and therapy of RSV-infected children and adults.