Investigation on Replicative aging in Cryptococcus neoformans populations

本申请涉及致病微生物如何适应和/或适应环境的毒力的一般问题。 逃脱宿主的防御并坚持下去大多数感染的特点是复杂的关系 这就是所谓的病理适应研究中的系统基于 新型隐球菌（CN），一种人类致病真菌，是死亡的主要原因， 艾滋病患者的发病率。这种真菌感染是出了名的难以治疗， 抗真菌治疗死亡率高，尤其是在疾病进展的艾滋病患者中。过程中 在R21资助的一项研究提案中，我们确定复制CN细胞经历了不对称细胞 分裂是导致世代或复制性衰老的过程。CN细胞经历有限数量的 在他们死之前，CN菌株的复制寿命（RLS）是一种可复制的性状， 通过显微解剖来确定。我们发现，复制年龄较大的CN细胞 在慢性感染期间持续存在，因为它们对过氧化氢应激更具抵抗力， 巨噬细胞胞内杀伤和抗真菌剂。我们现在提议调查 复制老化更详细，并具体阐明如何老化的新兴属性导致 选择较老的CN细胞在宿主中，并有助于持久性和毒力。我们的建议是 分为三个目标：（一）研究CN菌株中的RLS动力学ii.）为了研究为什么旧的CN细胞 对抗真菌剂和吞噬作用更有抗性iii.）研究和建模年龄依赖性 在体外和体内的复原力和脆弱性。

This application deals with a general problem in virulence of how pathogenic microbes adapt to and/or escape host defenses and persist. Most infections are characterized by a complex relationship between the host and the pathogen referred to as pathoadaptation. The system under study is based on Cryptococcus neoformans (CN), a human pathogenic fungus that is a major cause of mortality and morbidity in AIDS patients. This fungal infection is notoriously difficult to treat and despite effective antifungal therapy mortality is high especially in AIDS patients with progressive disease. In the course of a R21 funded research proposal we determined that replicating CN cells undergo asymmetric cell divisions a process that leads to generational or replicative aging. CN cells undergo a finite number of divisions before they die. The replicative life span (RLS) of a CN strain is a reproducible trait that can be determined through micro-dissection. We found that CN cells of advanced replicative age (older) persist during chronic infection because they are more resistant to hydrogen peroxide stress, macrophage intracellular killing, and antifungal agents. We now propose to investigate the process of replicative aging in more detail and specifically elucidate how the emerging properties of aging lead to selection of older CN cells in the host, and contribute to persistence and virulence. Our proposal is divided in three aims: I.) To investigate RLS dynamics in CN strains ii.) To investigate why old CN cells are more resistant to antifungals and phagocytosis iii.) To investigate and model age dependent resilience and vulnerability in vitro and in vivo.