Cryptococcus gatti mating loci; mapping and gene study

描述（由申请人提供）：隐球菌（Cn）引起隐球菌病，一种真菌性脑膜脑炎。病原体具有遗传上不同的变种（格鲁比变种、新形态变种和加蒂变种）和交配型（MATalpha和MATalpha）。这些变种在正常和免疫功能低下的个体中引起不同的宿主反应。这些致病差异背后的机制尚不清楚。格鲁比变异病毒是世界范围内隐球菌病最常见的病因；新形态变异感染主要在欧洲得到确认。直到最近，澳大利亚、东南亚和南美洲还报告了由加蒂变种病毒引起的原发性和机会性感染，北美的报告很少。随着目前在加拿大不列颠哥伦比亚省人类和动物中发生的一次重大加蒂变体暴发的报告，这种流行病学发生了巨大变化。目前，人们正在深入研究Cn交配，以确定真菌毒力与MATalpha之间的联系，并了解调控信号通路。近年来，grubii变种和新生变种的MATalpha和MATalpha基因座被定位，许多mat特异性基因在真菌生物学和毒力中的作用正在深入研究中。然而，这些强大的分子遗传学分析尚未扩展到变种。gatti，这将是必要的，以更好地了解其发病机制和开发更有效的治疗。从格鲁比变种和新生变种中获得的新知识被应用于该实验室，开发了基于DNA的快速测试，以识别所有变种和交配类型；进一步的研究表明，matα / α信息素具有品种特异性、拷贝数和染色体位置的差异以及跨品种交配和/或杂交的可能性。目前的提案建立在这些调查的基础上，专门关注var. gatti。我们的具体目标是：(i)鉴定、定位和系统发育研究包含MATalpha位点的基因，以及（ii）鉴定var. gatti STE12alpha cDNA，构建基因敲除突变体，研究突变表型和致病潜力。通过提供(a)包含MATalpha位点的基因遗传图谱，(b)鉴定STE12alpha在生物学和毒力中的作用，以及(c)未来真菌毒力遗传研究的框架，本研究可能有助于更好地了解gatti变种的致病性。

DESCRIPTION (provided by applicant): Cryptococcus neoformans (Cn) causes cryptococcosis, a fungal meningoencephalitis. The pathogen has genetically distinct varieties (var. grubii, var. neoformans, and var. gattii) and mating types (MATalpha and MATalpha). These varieties elicit different host responses in normal and immunocompromised individuals. The mechanisms underlying these pathogenic differences are not well understood. Cn var. grubii is the most common cause of cryptococcosis worldwide; var. neoformans infections have been mostly recognized in Europe. Both primary and opportunistic infections due to var. gattii were till recently reported from Australia, Southeast Asia and South America with rare reports from North America. This epidemiology has changed dramatically with the current report of a major var. gattii outbreak in humans and animals in British Columbia, Canada. Currently, Cn mating is under intensive investigations to define the observed linkage between fungal virulence and MATalpha, and to understand the regulatory signaling pathways. Recently, MATalpha and MATalpha loci from var. grubii and var. neoformans were mapped, and many MAT-specific genes are under intensive study for their role in fungal biology and virulence. However, these powerful molecular genetic analyses have not yet been extended to var. gattii, which will be essential for better understanding of its pathogenesis and the development of more effective therapy. The emerging knowledge from var. grubii and var. neoformans was applied in this laboratory to develop DNA based rapid tests to identify all varieties and mating types; further study of MATalpha/alpha pheromones revealed variety specificity, different copy numbers, and chromosomal locations, and a potential for cross-variety mating and/or hybridization. The current proposal builds upon these investigations by focusing exclusively on var. gattii. Our specific goals are: (i) identification, mapping and phylogenetic studies of genes comprising MATalpha locus, and (ii) characterization of var. gattii STE12alpha cDNA, construction of gene knockout mutants, and study of mutant phenotypes and pathogenic potential. This study may lead to better understanding of var. gattii pathogenicity by providing (a) a genetic map of genes comprising MATalpha locus, (b) characterization of the role of STE12alpha in biology and virulence, and (c) a framework for future genetic investigations of fungal virulence.