The evolution of virulence in the fungal pathogen Histoplasma

摘要/项目总结 背景：组织胞浆菌是一种致病真菌，可引起危及生命的肺部感染。约50万 在美国，每年都有500人暴露于组织胞浆菌，超过60%的美国人口 在生命的某个阶段接触过真菌我们已经证明，组织胞浆菌是由at 至少有五种不同的物种，在它们引起的疾病的类型和程度上差异很大。 广泛的，长期的目标：拟议的研究将帮助我们确定基因，使毒力， 出现并传播，并开发出一组分离株，一旦深度测序， 医学真菌学家社区绘制组织胞浆菌的任何感兴趣的特征。本提案的目的是 为了发现导致分离株毒力差异的基因是否在不同的地方相似， 物种 具体目标：研究的目标1建议为三个物种的遗传参考面板， 人类病原体组织胞浆菌我们将利用这一资源来确定与毒力差异有关的等位基因 在物种之间和物种之间。目标2将在遗传上测试表型效应（即，体外和体内毒力） Aim 1中产生的基因组假设。目的3将研究等位基因在临床样本中的传播， 40年，并将综合目标1和2的结果，使我们能够确定是否有任何 与毒力有关的等位基因频率增加。 方法：这种单倍体生物体是真菌病原体实验室研究的理想选择， 基因组分析我们将生成三种不同组织胞浆菌属的遗传参考板， 最先进的基因组工具和全基因组关联图谱。我们将使用这个面板来识别 同一物种分离株毒力差异的遗传基础。值得注意的是，我们将在网上生成一个 分析GWAS数据的门户网站，这是医学真菌学界的第一个。初步结果显示，鉴于 毒力表型变异量、我们的方法和建议的样本量使得这个项目 可行候选毒力基因的验证将根据已建立的细胞培养和 小鼠感染测定。我们的方法将为真菌遗传学提供工具和参考面板 社区 健康相关性：在美国，组织胞浆菌属引起的疾病负担很大， 保守估计每10万人至少有3.4例。如果传染性菌株可以传播 通过基因交换导致感染危害较小的菌株的能力，潜在的未来疾病负担将 随着全球贸易、旅行和气候变化将新的真菌物种带入重叠的地理区域， 地区拟议的研究将确定哪些位点参与毒力的进化，并将研究 自然选择在它们进化过程中的影响本申请是回应一项 最近NIH资助机会公告（PA-19-082）支持组织胞浆菌病的研究， 其他地方性真菌病，该计划特别鼓励提交R 01申请， 将“扩大对物种形成和对临床结果影响的理解”。

ABSTRACT/PROJECT SUMMARY Background: Histoplasma is a pathogenic fungus that causes life-threatening lung infections. About 500,000 people are exposed to Histoplasma each year in the United States, and over 60% of the US population has been exposed to the fungus at some point in their life. We have shown that Histoplasma is composed of at least five different species that vary considerably in the type and magnitude of disease they cause. Broad, long-term objective: The proposed research will help us identify the genes that allow virulence to emerge and spread, as well as develop a panel of isolates that once deep-sequenced can be used by the community of medical mycologists to map any trait of interest in Histoplasma. The objective of this proposal is to discover whether the genes responsible for differences in virulence among isolates are similar across species. Specific aims: Aim 1 of the study proposes to generate genetic reference panels for three species of the human pathogen Histoplasma. We will use this resource to identify alleles involved with virulence differences within and between species. Aim 2 will genetically test the phenotypic effects (i.e., virulence in vitro and in vivo) of the genomic hypotheses produced in Aim1. Aim 3 will study the spread of alleles in clinical samples over a period of 40 years and will integrate the results from Aims 1 and 2, allowing us to determine whether any of the alleles involved in virulence have increased in frequency. Method: This haploid organism is ideal for the laboratory study of fungal pathogens, and it is well-suited for genomic analysis. We will generate genetic reference panels for three different species of Histoplasma with state-of-the-art genomic tools and genome-wide association mapping. We will use this panel to identify the genetic basis of virulence differences within isolates of the same species. Notably, we will generate an online portal to analyze GWAS data, a first in the medical mycology community. Preliminary results show that given the amount of phenotypic variance in virulence, our approach and proposed sample sizes make this project feasible. Validation of candidate virulence genes will be undertaken according to established cell culture and mouse infection assays. Our approach will generate tools and reference panels for the fungal genetics community. Health-relatedness: The disease burden caused by Histoplasma species is substantial in the United States, with a conservative estimate of at least 3.4 cases per 100,000 population. If infectious strains can transmit the ability to cause infection to less harmful strains through gene exchange, the potential future disease burden will grow as global trade, travel and climate change bring new species of the fungus into overlapping geographic regions. The proposed research will identify what loci are involved in the evolution of virulence and will study the influence of natural selection in their evolution in recent timescales. This application is in response to a recent NIH Funding Opportunity Announcement (PA-19-082) supporting research on histoplasmosis and two other endemic fungal diseases, and this program specifically encourages submission of R01 applications that will “expand understanding of speciation and impact on clinical outcome.”