The evolution of virulence in the fungal pathogen Histoplasma

摘要/项目摘要 背景：组织胞浆是一种致病真菌，可引起危及生命的肺部感染。约500,000 在美国，每年人们都会接触到组织胞浆虫，超过60%的美国人口患有 在他们一生中的某个时候接触过这种真菌。我们已经证明组织胞浆是由at组成的。 至少五个不同的物种，它们引起的疾病的类型和程度有很大的差异。 广泛的、长期的目标：拟议中的研究将帮助我们识别允许毒力 出现和传播，以及开发一组分离株，一旦进行深度测序，就可以被 医学真菌学家社区绘制任何感兴趣的组织胞浆体特征图。这项提议的目标是 为了发现导致不同毒力菌株之间毒力差异的基因是否在 物种。 具体目标：研究的目标1建议为三个物种建立遗传参考板 人类病原体组织胞浆。我们将利用这个资源来鉴定与毒力差异有关的等位基因。 在物种内部和物种之间。AIM 2将从基因上测试表型效应(即体外和体内的毒力) 在Aim1中产生的基因组假说。目标3将研究等位基因在临床样本中的传播 并将综合目标1和目标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的频率增加了。 方法：这种单倍体微生物非常适合于真菌病原菌的实验室研究，它非常适合于 基因组分析。我们将为三种不同的组织胞浆体生成遗传参考板 最先进的基因组工具和全基因组关联图谱。我们将使用此面板来标识 同种菌株内毒力差异的遗传基础。值得注意的是，我们将生成一个在线 分析Gwas数据的门户，这在医学真菌学社区中是第一次。初步结果表明，给定的 毒力的表型变异量、我们的方法和建议的样本量使这个项目 可行。候选毒力基因的验证将根据已建立的细胞培养和 小鼠感染检测。我们的方法将为真菌遗传学产生工具和参考板 社区。 与健康相关：在美国，组织胞浆体种造成的疾病负担很大， 保守估计每10万人中至少有3.4例。如果传染性菌株可以传播 通过基因交换对危害较小的菌株造成感染的能力，未来潜在的疾病负担将 随着全球贸易、旅行和气候变化将这种真菌的新物种带入重叠的地理区域而增长 地区。拟议中的研究将确定哪些基因与毒力的进化有关，并将研究 在最近的时间尺度上自然选择在它们进化中的影响。此应用程序是对 美国国立卫生研究院最近宣布的资助机会(PA-19-082)支持组织胞浆菌病和两项研究 其他地方性真菌病，该计划特别鼓励提交R01申请 将“扩大对物种形成和对临床结果的影响的理解。”

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.”