Global Genomic and Proteomic Profiling of African Children with Typhoid Fever

描述(由申请人提供)：伤寒是由伤寒沙门氏菌(伤寒沙门氏菌)引起的，伤寒是一种人类特有的病原体。世界卫生组织(WHO)承认伤寒是一个全球健康问题，估计每年有2100万例伤寒病例，20万至60万人死亡。在非洲和南亚，幼儿是疾病负担最高的一个亚群。这种疾病的发病是隐匿的，临床诊断往往不可靠。通过血液或骨髓培养确定诊断是劳动密集型、昂贵和侵入性的，敏感性为40%至70%。世卫组织建议常规接种伤寒疫苗，但目前获得许可的疫苗对该疾病的保护率仅为55-75%。因此，迫切需要为伤寒仍是主要公共卫生负担的国家开发快速、敏感和廉价的诊断方法以及更有效的疫苗。我们的长期目标是1)开发创新的分子诊断分析方法，用于快速和廉价地检测伤寒；2)更好地了解宿主反应的分子机制，以促进下一代伤寒疫苗的开发。我们的近期目标是获得感染伤寒沙门氏菌的非洲儿童的全球基因表达和蛋白质组图谱，鉴定和验证 分类基因和蛋白质作为潜在的诊断生物标记物和疫苗靶标。自2008年以来，我们已经在尼日利亚中部建立了菌血症监测系统。一项试点研究是从一小群患有伤寒的尼日利亚儿童中发起的。我们的初步数据显示，与其他细菌性感染以及急性期和恢复期的患者相比，伤寒儿童外周血中宿主反应的基因表达谱具有独特性。在这里，我们假设可以根据外周血和血清中的宿主反应获得不同的分类基因和蛋白，以区分伤寒与其他细菌性感染和健康对照。我们的具体目标是：1)使用基因表达(GE)微阵列确定伤寒特异性宿主反应分类基因，2)使用新建立的伤寒蛋白质组微阵列发现特定的血清抗伤寒蛋白，并建立急性伤寒的原型血清学分析(ELISA)3)使用新的独立队列验证分类基因和现场测试原型ELISA。为了实现这些目标，我们组建了一支拥有传染病、免疫学、分子基因组学/蛋白质组学、微阵列和生物信息学专业知识的多学科团队，以确保该项目的成功。这些研究将根据免疫反应识别伤寒感染的不同分类基因和蛋白。区分伤寒沙门氏菌和其他菌血症的分类器有可能开发并提供针对伤寒的快速、廉价、非侵入性和灵敏的分子诊断方法。从我们新的定制全蛋白质组伤寒微阵列中获得的分类蛋白质将为下一代疫苗开发提供目标蛋白质和抗体的新见解。

DESCRIPTION (provided by applicant): Typhoid fever is caused by Salmonella enteric serovar Typhi (S. typhi), a human specific pathogen. The World Health Organization (WHO) recognizes typhoid fever as a global health problem, with an estimated 21 million cases and 200,000-600,000 deaths annually. In Africa and South Asia, young children represent a subgroup with the highest disease burden. The onset of the illness is insidious and clinical diagnosis is often unreliable. Definitive diagnosis through blood or bone-marrow culture is labor-intensive, expensive, and invasive, with a sensitivity of 40 to 70%. WHO recommends routine typhoid fever vaccination but currently licensed vaccines provide only 55-75% protection against the disease. Therefore, there is an urgent need to develop rapid, sensitive, and inexpensive diagnostic methods, as well as more efficacious vaccines for countries where typhoid fever remains a major public health burden. Our long term goals are 1) to develop innovative molecular diagnostic assays for rapid and inexpensive detection of typhoid fever and, 2) to better understand the molecular mechanisms of host response to facilitate the development of next-generation typhoid fever vaccines. Our immediate objective is to obtain global gene expression and proteomic profiles of S. typhi- infected African children, identify and validate the classifier genes and proteins as potential diagnostic biomarkers and vaccine targets. We have already established a bacteremia surveillance system in central Nigeria since 2008. A pilot study was initiated from a small cohort of Nigerian children with typhoid fever. Our preliminary data showed unique gene expression profiles of host response in peripheral blood of children with typhoid fever compared with other bacteremic infections, as well as patients in acute vs. convalescent phase. Here, we hypothesize that distinct classifier genes and proteins based on host response in the peripheral blood and serum can be obtained to discriminate typhoid fever from other bacteremic infections and healthy controls. Our specific aims are: 1) Define typhoid fever-specific host response classifier genes using gene expression (GE) microarrays, 2) Discover specific serum anti-typhoid fever proteins using newly established S. typhi proteome microarrays and develop prototype serologic assay for acute typhoid (ELISA) 3) Validate classifier genes and field-test prototype ELISAs using new, independent cohorts. To accomplish these objectives, we have assembled a multidisciplinary team with expertise in infectious disease, immunology, molecular genomics/proteomics, microarrays, and bioinformatics to ensure success of this project. These studies will identify distinct classifier genes and proteins f typhoid fever infection based on immunological responses. Classifiers that discriminate S. typhi from other bacteremia are possible to develop and offer rapid, inexpensive, non-invasive, and sensitive molecular diagnostic assays specific for typhoid fever. Classifier proteins obtained from our new, custom whole-proteome typhoid fever microarrays will provide new insights of targeted proteins and antibodies for next-generation vaccine development.