The Genetic Basis of Virulence in Cryptococcus Neoformans

项目摘要 据估计，真菌病原体新型隐球菌（Cryptococcus neoformans）在超过100万人中引起疾病。 全球每年有100万人死亡，导致超过60万人死亡。但并非所有 隐球菌分离株引起致命感染;有些是相对良性的，而另一些是hypervir。 乌利。致病性的差异通常与特定形态的变异有关。 和生理特征，如在高温下生长的能力，亲， 酵母细胞周围的保护性多糖被膜，或抗真菌药物的耐药性。在 为了开发更好的方法来预防和治疗隐球菌病，我们需要了解 潜在的遗传差异导致毒力和毒力相关性状的变化。我们 我们还需要了解这些遗传差异在不同地区的频率和分布， 世界各地。 为了解决这些问题，拟议的研究将使用实验和 用统计学方法剖析毒力和毒力变异的因果遗传基础- 相关特征。在目标1中，我们将采用一种称为数量性状基因座的统计技术 (QTL)映射，利用后代之间的基因型和表型差异， 从遗传杂交中识别基因组区域（基因座）和DNA变化（等位基因）， 归因于毒力特征的差异。我们将验证已识别位点的贡献 通过基因替换和相关技术。在目标2中，我们将主题- 隐球菌的遗传多样性种群在动物宿主中的选择。在选择之后， 汇集的全基因组测序将用于鉴定在基因组测序期间有利的基因座和等位基因。 感染该技术提供了一种无偏倚的方法，用于发现有助于 毒力，并将补充和扩展目标1的结果。在目标3中，我们将 在隐球菌自然种群的背景下，通过研究频率和地理位置， 目的1和2中鉴定的毒力等位基因的图形分布艾德。这一目标将采用一个大的， 从临床环境和自然环境中分离的隐球菌菌株的全球样本， 我是说。这些信息将用于进行全基因组关联（GWAS）作图， 毒力性状，并确定世界上有较高频率的毒力 基因型或存在通过重组增加毒力的潜力。

Project Summary The fungal pathogen Cryptococcus neoformans is estimated to cause disease in more than 1,000,000 people worldwide every year, resulting in greater than 600,000 deaths. However, not all Cryptococcus isolates cause lethal infections; some are relatively benign while others are hypervir- ulent. Differences in pathogenicity are often correlated with variation in specific morphological and physiological features such as the ability to grow at high temperatures, the size of the pro- tective polysaccharide capsule surrounding the yeast cell, or resistance to antifungal drugs. In order to develop better ways to prevent and treat cryptococcal disease we need to understand the underlying genetic differences that lead to changes in virulence and virulence-related traits. We also need to understand the frequency and distribution of these genetic differences in different parts of the world. To tackle these problems, the proposed research will use a combination of experimental and statistical approaches to dissect the causal genetic basis of variation in virulence and virulence- related traits. In Aim 1 we will employ a statistical technique called Quantitative Trait Locus (QTL) mapping, that exploits genotypic and phenotypic differences among offspring derived from genetic crosses to identify regions of the genome (loci) and DNA changes (alleles) that con- tribute to differences in virulence traits. We will validate the contributions of the loci identified in this manner using gene replacements and related techniques. In Aim 2 we will subject ge- netically diverse populations of Cryptococcus to selection in animal hosts. Following selection, pooled whole genome sequencing will be used to identify loci and alleles that are favored during infection. This technique provides an unbiased approach for discovering loci that contribute to virulence, and will both complement and extend the results of Aim 1. In Aim 3 we will frame our findings in the context of natural populations of Cryptococcus by studying the frequency and geo- graphic distributions of virulence alleles identified in Aims 1 and 2. This aim will employ a large, global sample of Cryptococcus strains isolated from both clinical settings and the natural environ- ment. This information will be used to carry out Genome-Wide Association (GWAS) mapping of virulence traits and to identify regions of the world where there are higher frequencies of virulent genotypes or where there is potential for increased virulence through recombination.