SWITCHING IN THE ORAL COMMENSAL CANDIDA GLABRATA

描述（由申请人提供）：光滑念珠菌作为老年人口腔中的主要真菌和第二常见的酵母菌血流感染的出现是一个令人担忧的问题。由于光滑念珠菌具有天然耐药性，它使老年人和免疫功能低下的人处于危险之中，并导致难以治疗的慢性感染。然而，这种病原体的成功令人困惑，因为与白色念珠菌不同，它似乎既不经历高频表型转换，也不经历二型性，这两种发育程序为发病机制的快速适应提供了机制。因此，我们在C语言中寻找并发现了这两种发展程序。光滑的C. glabrata在含CuSO 4琼脂上可区分的四种“核心”表型（白色（Wh）、浅棕色（LB）、深棕色（DB）和极深棕色（vDB））之间自发地、可逆地和高频率地转换，并且另外转换成两种“相关”转换表型（不稳定的白色（unWh）和不规则皱纹（IWr））和从两种“相关”转换表型转换。核心转换的独特之处在于，所有测试的表型特征和转换调节基因的表达都在以下层次中分级：Wh小于LB小于DB小于vDB或Wh大于LB大于DB大于vDB。基于这一独特的分级开关系统的发现，以及最近提出的慢性阴道炎患者口腔和阴道中核心开关表型的解剖学特化，提出了以下具体目标：1）完成开关的表征并定义相关开关表型和核心开关系统的关系; 2）通过差异杂交筛选和使用S.基于酿酒酵母cDNA的阵列; 3）使用REMI诱变，鉴定和表征参与转换过程的基因; 4）功能性地表征参与分级表达的顺式作用序列和反式作用因子; 5）区分参与unWh和IWr表型的基因和参与假菌丝和芽生长形式的基因，和6）测试转换是否影响药物敏感性，其他毒力性状和动物模型中的毒力，并确认核心开关表型表现出解剖学特化。

DESCRIPTION (provided by applicant): The emergence of Candida glabrata as a major commensal in the oral cavity of the elderly, and as the second most common yeast blood stream infection is a matter of dire concern. Because Candida glabrata is naturally drug-resistant, it puts at risk the elderly and immunocompromised, and causes chronic infections that an difficult to treat. The success of this pathogen, however, was puzzling since, unlike Candida albicans, it appeared to undergo neither high frequency phenotypic switching nor dimorphism, two developmental programs that provide mechanism for rapid adaptation in pathogenesis. We, therefore, searched for and discovered both developmental programs in C. glabrata. C. glabrata switches spontaneously, reversibly and at high frequency between four "core" phenotypes distinguishable on CuSO4-containing agar, white (Wh), light brown (LB), dark brown (DB) and very dark brown (vDB), and in addition switch to and from two "associated" switch phenotypes, unstable white (unWh) and irregular wrinkle (IWr). Core switching is unique in that all tested phenotypic characteristics and the expression of switching-regulated genes are graded in the hierarchies Wh less than LB less than DB less than vDB or Wh greater than LB greater than DB greater than vDB. Based upon the discovery of this uniquely graded switching system, and the recent suggestion of anatomical specialization of core switch phenotypes in the oral cavity and vagina of a chronic vaginitis patient, the following specific aims are proposed: 1) complete the characterization of switching and define the relationship of the associated switch phenotypes and the core switching system; 2) identify and characterize additional switching-regulated genes by differential hybridization screens and the use of S. cerevisiae cDNA-based arrays; 3) using REMI mutagenesis, identify and characterize genes involved in the switching process; 4) functionally characterize the cis-acting sequences and trans-acting factors involved in the graded expression; 5) discriminate between genes involved in the unWh and IWr phenotypes and genes involved in the pseudohypha and bud growth forms and 6) test whether switching affects drug susceptibility, other virulence traits and virulence in animal models, and confirm that the core switch phenotypes exhibit anatomical specialization.