The Genetic Basis of Virulence in Cryptococcus Neoformans

项目摘要 据估计，真菌病原体新生隐球菌导致的疾病超过 全球每年有100万人死亡，造成60多万人死亡。然而，并不是所有的 隐球菌分离株会导致致命的感染；一些相对良性，而另一些则高度活跃-- 可恶。致病性的差异往往与fi-c形态的变异有关。 以及生理特征，如在高温下生长的能力，蛋白质的大小- 包被酵母细胞的保护性多糖胶囊，或对抗真菌药物产生抗药性。在……里面 为了开发更好的方法来预防和治疗隐球菌疾病，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 还需要了解这些遗传差异在不同地区的频率和分布 世界上的一些地方。 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原因遗传基础-- 相关特征。在目标1中，我们将使用一种称为数量性状基因座的统计技术 (QTL)定位，利用后代的基因和表型差异 从遗传杂交中识别基因组的区域(位点)和DNA变化(等位基因)，这些区域包含 致敬于毒力特征的差异。我们将验证标识基因座fied的贡献 以这种方式使用基因替换和相关技术。在目标2中，我们将研究GE- 动物宿主中隐球菌群的新多样性。在选择之后， 混合全基因组测序将被用来识别在 感染。这项技术提供了一种无偏见的方法来发现有助于 毒性，并将补充和扩展目标1的结果。在目标3中，我们将制定我们的 通过研究隐球菌在自然种群中的频率和地理分布来进行fi编码 在目标1和2中识别的毒力等位基因fi的图形分布。这一目标将利用大量的， 从临床环境和自然环境中分离的隐球菌菌株的全球样本- 门槛。这些信息将被用来进行全基因组关联(GWAS)作图 毒力特征，并识别世界上毒力频率较高的地区 基因类型或有可能通过重组提高毒力的地方。

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.