The Genetic Basis of Virulence in Cryptococcus Neoformans

摘要 隐球菌属致病真菌每年导致全世界近 20 万人死亡 宽。然而，并非所有隐球菌分离株都会引起致命的感染；有些是相对良性的 而另一些则毒性很强。致病性的差异通常与变异相关 特定的形态和生理特征，例如在高温下生长的能力 结构，围绕酵母细胞的保护性多糖胶囊的大小，或对 抗真菌药物。为了增进对隐球菌生物学和隐球菌疾病的了解， 我们试图找出导致病毒变化的分离株和物种之间的遗传差异 强度和毒力相关特征，以理清遗传变异对基因网络的影响 以及控制这些特征的途径，并了解有助于的生态相互作用 至发病机制。 我们建议应用群体和定量基因组方法以及微生物经验 心理进化来剖析毒力变异的遗传基础和毒力相关特征 隐球菌。我们提出了三个相互关联的具体目标： 目标 1) 绘制人口图并 在新型隐球菌、新隐球菌中进行数量性状位点（QTL）作图 人类和格特隐球菌鉴定导致毒力差异的基因和等位基因 性状和抗真菌药物耐药性；目标 2) 采用一种新颖的化学上位方法 剖析自然变异对信号通路和转录网络的影响 控制毒力特征；目标 3) 利用性状作图和实验进化来识别 调节隐球菌和吞噬阿米巴原虫之间相互作用的遗传变异和测试 这些变异是否与真菌疾病细胞和动物模型中的毒力相关。

Abstract Pathogenic fungi of the genus Cryptococcus contribute to nearly 200,000 deaths annually world- wide. However, not all Cryptococcus isolates cause lethal infections; some are relatively benign whereas others are hypervirulent. Differences in pathogenicity are often correlated with variation in specific morphological and physiological features such as the ability to grow at high tempera- tures, the size of the protective polysaccharide capsule surrounding the yeast cell, or resistance to antifungal drugs. To advance the understanding of Cryptococcus biology and cryptococcal disease, we seek to identify genetic differences between isolates and species that lead to changes in viru- lence and virulence-related traits, to disentangle the effects of genetic variants on gene networks and pathways that govern such traits, and to understand the ecological interactions that contribute to pathogenesis. We propose to apply population and quantitative genomic approaches and microbial experi- mental evolution to dissect the genetic basis of variation in virulence and virulence-related traits in Cryptococcus. We propose three inter-related specific aims: Aim 1) Build mapping populations and carry out Quantitative Trait Locus (QTL) mapping in Cryptococcus neoformans, Cryptococcus deneofor- mans, and Cryptococcus gattii to identify genes and alleles that contribute to differences in virulence traits and resistance to anti-fungal drugs; Aim 2) Employ a novel chemical epistasis approach to dissect the impact of natural variation on signaling pathways and transcriptional networks that control virulence traits; and Aim 3) Utilize trait mapping and experimental evolution to identify genetic variants that modulate interactions between Cryptococcus and phagocytic amoeba and test whether these variants correlate with virulence in cellular and animal models of fungal disease.