Examining the role of opportunistic human pathogen Aspergillus flavus in fungal keratitis eye infections

项目摘要 曲霉菌是人类真菌感染的主要原因，是这两种疾病的病原体。 曲霉菌病、呼吸道感染和真菌性角膜炎(FK)眼部感染。FK可能需要角膜 否则会造成灾难性的失明后果。据报道有100多万新的FK病例 每年在全球范围内。FK的主要危险因素是使用隐形眼镜和眼睛表面划痕， 允许角膜感染；当真菌生长到角膜中时，就会发生损害。 丝状真菌黄曲霉是FK感染的主要原因，是从FK中分离出来的 角膜溃疡比任何其他曲霉物种都更常见，包括关系密切的曲霉，如A. Parasiticus、A.noius和A.archidicola。已知黄曲霉在人体温度下生长。 (37°C)，产生称为真菌毒素的生物活性次生代谢物，并耐受高盐度水平，所有这些 其中一些被认为与人类眼睛的感染和生长有关。然而，我们并不理解 哪些致病力的遗传决定因素是黄曲霉所特有的？这些决定因素的变异是如何起作用的？ 黄曲霉引起FK的能力在种内和种间的差异。 我的项目的目标是了解是什么使黄曲霉成为一种成功的病原体，而当其他细菌 相关的广泛存在的曲霉菌并不具有致病性，也能洞察致病性的变异。 在黄曲霉体内。我推测黄曲霉基因组包括独特的毒力遗传决定因素缺失。 来自相关物种。这些可能是黄曲霉和黄曲霉中唯一存在或不存在的基因或变体。 密切相关的非病原体，如参与次生代谢的基因(次生代谢物通常 影响寄主生物学)。我们也还不知道遗传多样性、抗真菌药物耐受性水平或表型。 引起FK的黄曲霉菌株对高温或盐度的反应。我假设遗传和表型特征 在黄曲霉和非致病亲缘中存在的差异也会影响毒力。 为了验证这些假设，我建议首先检查曲霉物种和 在黄曲霉内鉴定毒力的假定遗传决定因素，并检查独特的影响 无脊椎动物疾病模型中毒力的决定因素。第二，我会调查盐度的影响， 热、抗真菌药物对黄曲霉及其近缘种生长表型和化学组成的影响 研究黄曲霉特有的次生代谢物对其在无脊椎动物体内毒力的影响 疾病的模型。拟议的实验将使我能够识别遗传元素的关键差异 黄曲霉和相关物种之间的关系，并提供了临床和 以及黄曲霉和黄曲霉的生理反应特性。 将非致病物种与感染相关的条件联系起来。

Project Summary Aspergillus species are a leading cause of fungal infections in humans as the disease agents for both aspergillosis respiratory infections and fungal keratitis (FK) eye infections. FK can necessitate a corneal transplant or have the devastating consequence of blindness. Over a million new cases of FK are reported annually worldwide. The primary risk factors for FK are contact lens use and surface scratches on the eye, which allow infection of the cornea; damage occurs as the fungus grows into the cornea. The filamentous fungus Aspergillus flavus is a leading cause of FK infections and is isolated from FK corneal ulcers more frequently than any other Aspergillus species, including closely related ones, such as A. parasiticus, A. nomius, and A. arachidicola. A. flavus is known to grow at the temperature of the human body (37°C), to produce bioactive secondary metabolites known as mycotoxins, and to tolerate high salinity levels, all of which are thought to be relevant for infection and growth in the human eye. However, we do not understand what genetic determinants of virulence are unique to A. flavus or how variation in these determinants contributes to within- and between-species variation in the ability of A. flavus to cause FK. The goal of my project is to understand what makes A. flavus a successful pathogen when other closely related, widespread Aspergillus species are not pathogenic as well as gain insights into variation in pathogenicity within A. flavus. I hypothesize that the A. flavus genome includes unique genetic determinants of virulence absent from related species. These may be genes or variants that are uniquely present or absent in A. flavus versus closely related non-pathogens, such as genes involved in secondary metabolism (secondary metabolites often affect host biology). We also do not yet know the genetic diversity, antifungal drug tolerance levels, or phenotypic responses to heat or salinity of FK-causing A. flavus isolates. I hypothesize that genetic and phenotypic traits differentially present in A. flavus and nonpathogenic relatives will also impact virulence. To test these hypotheses, I propose to first examine genomic diversity among Aspergillus species and within A. flavus to identify putative genetic determinants of virulence, and to examine the impact of unique determinants on virulence in an invertebrate model of disease. Second, I will investigate the impact of salinity, heat, and antifungal drugs on growth phenotypes and chemical profiles of A. flavus and related species, and to study the impact of secondary metabolites that are uniquely present in A. flavus on its virulence in an invertebrate model of disease. The proposed experiments will enable me to identify key differences in genetic elements between A. flavus and related species and provide a snapshot of population structure of clinical and environmental isolates within A. flavus, as well as characterize the physiological responses of A. flavus and related non-pathogenic species to infection-relevant conditions.