T. Gondii: Pyrimidine Synthesis as a Chemo Target

描述（由申请人提供）：弓形虫慢性感染约30%的美国人口，并导致严重的危及生命的弓形虫脑炎感染艾滋病。目前的药物治疗不能很好地耐受，并且因为这些治疗对缓慢生长的缓殖子阶段几乎没有影响，潜伏的寄生虫仍然是艾滋病复发感染的来源。迫切需要能够靶向速殖子和缓殖子阶段的更有效的疗法来治疗急性感染以及预防由寄生虫复发引起的弓形虫病。我们的初步研究表明，破坏从头嘧啶合成途径中的氨甲酰磷酸合成酶II（CPSII）会导致严重的尿嘧啶营养缺陷型，相应的寄生虫生长和毒力损失。因此，嘧啶生物合成途径似乎是一个很好的干预目标，嘧啶收购的基础研究有可能确定新的目标。由于在所有生命阶段都需要尿苷一磷酸，我们假设嘧啶生物合成是维持快速速殖子复制以及组织包囊内缓殖子生存能力所必需的。我们建议使用遗传学、生物化学和细胞生物学方法的组合来更好地理解T.刚地。嘧啶生物合成的抑制剂将基于嘧啶营养缺陷型的筛选策略来鉴定。我们研究中开发的信息和试剂将用于验证该途径中的重要药物靶标，以及验证本项目中确定的抑制剂靶标。这些研究将有助于开发新的治疗药物来治疗急性感染，并可能有助于开发第一种能够清除慢性感染以消除艾滋病中再活化弓形虫脑炎的治疗药物。公共卫生相关性：该研究项目将使用基本的遗传学、生物化学和药物筛选方法来验证药物靶点并鉴定弓形虫嘧啶生物合成的抑制剂。因此，该研究项目将加速发现新的疫苗和治疗艾滋病中毁灭性的机会性寄生虫感染的方法。

DESCRIPTION (provided by applicant): Toxoplasma gondii chronically infects approximately 30% of the USA population and causes severe life-threatening Toxoplasmic encephalitis infections in AIDS. Current drug treatments are not well tolerated, and because these treatments have little effect on the slow growing bradyzoite stages, latent parasites remain as a source of recrudescing infection in AIDS. More effective therapies that can target both tachyzoite and bradyzoite stages are urgently needed to treat acute infections as well as to prevent the toxoplasmosis caused by recrudescing parasites. Our preliminary studies have demonstrated that disruption of carbamoyl phosphate synthetase II (CPSII) in the de novo pyrimidine synthesis pathway causes a severe uracil auxotrophy with a corresponding loss of parasite growth and virulence. Consequently the pyrimidine biosynthetic pathway appears to be an excellent target for intervention, and fundamental studies on pyrimidine acquisition have the potential to identify new targets. Due to the need for uridine monophosphate in all life stages, we hypothesize that pyrimidine biosynthesis is necessary to sustain rapid tachyzoite replication as well as the viability of bradyzoites within tissue cysts. We propose to use a combination of genetic, biochemical, and cell biological approaches to better understand the fundamental biology of de novo pyrimidine synthesis and salvage pathways in T. gondii. Inhibitors of pyrimidine biosynthesis will be identified based on a screening strategy of pyrimidine auxotrophy. The information and reagents developed in our studies will be used to validate significant drug targets in the pathway as well as to validate the target(s) of inhibitors identified in this project. These studies will contribute to the development of new therapeutic agents to treat acute infections and may contribute to the development of the first therapeutic agents capable of clearing chronic infection to eliminate reactivation Toxoplasmic encephalitis in AIDS. PUBLIC HEALTH RELEVANCE: This research project will validate drug targets and identify inhibitors of pyrimidine biosynthesis in Toxoplasma gondii using fundamental genetic, biochemical, and drug screening approaches. Consequently, this research project will accelerate the discovery of new vaccines and treatments for devastating opportunistic parasite infections in AIDS.