A Genomics Approach to Study C. neoformans var. grubii

描述（由申请人提供）：新型隐球菌是一种人类病原体，可在免疫功能低下和免疫功能正常的宿主中引起危及生命的脑膜脑炎。该生物是单倍体，具有明确的性周期，具有发达的分子生物学研究工具，以及用于毒性研究的强大动物模型。基因组的基本结构很好地表征了，大约20MB分布在12到14条染色体上。目前，一个基因组联盟正在对一种具有代表性的实验室菌株JEC21的基因组进行测序。预计JEC21序列将在12个月内完成。

DESCRIPTION (provided by applicant): Cryptococcus neoformans is a human pathogen that causes life threatening meningoencephalitis in immunocompromised and immunocompetent hosts. The organism is haploid and has a defined sexual cycle, well developed molecular biology research tools, and robust animal models for virulence studies. The basic structure of the genome is well characterized, being about 20MB distributed over 12 to 14 chromosomes. Currently a genome consortium is sequencing the genome of one representative laboratory strain, JEC21. It is anticipated that the JEC21 sequence will be completed within 12 months. There is considerable diversity among C. neoformans isolates. Isolates have been divided into four serotypes which differ by 10% or more at the DNA sequence level. Debate continues over whether these serotypes (A, B, C, D) should be considered different varieties or species. What is important is that these serotypes differ in not only their polysaccharide capsular antigens, but also in physiological properties and in pathogenicity. The most direct and efficient way to address the underlying nature of variation and its relationship to pathogenicity in C. neoformans is a comparative genomics approach taking advantage of the JEC21 sequence, in comparison with the sequence of a serotype A clinical isolate. JEC21 is a laboratory adapted strain derived from a clinical isolate and an environmental isolate by 12 backcrosses and may be attenuated for virulence. We thus propose to determine and annotate the complete sequence of C. neoformans serotype A strain H99. Greater than 90% of all clinical isolates and 99% of all isolates from AIDS patients are of serotype A, and strain H99 is a well characterized clinical isolate. In collaboration with the Vancouver Genome Center, we have produced the preliminary material and results to establish the feasibility of completing the genome in the manner described in this application. We also propose developing the basic resources to exploit this comparative data, namely a careful analysis of the differences between these two strains and a series of microarrays for genotyping of Cryptococcus strains. The resulting data and material from this study will expand our knowledge of the nature of pathogenicity in this important human fungal pathogen.