Exploring Novel Targeting Strategies for AIDS Protozoal Pathogens

 描述（由申请人提供）：世界卫生组织估计，截至2012年底，超过3500万人感染了HIV-1（人类免疫缺陷病毒）。由于高效抗逆转录病毒疗法（HAART）的进步，与艾滋病有关的死亡人数有所减少，个人寿命延长。尽管HAART取得了成功，但机会性感染仍然是艾滋病患者死亡的主要原因之一。其中最普遍的是原生动物寄生虫病原体隐孢子虫。隐孢子虫病是以严重的慢性腹泻为特征的艾滋病定义疾病之一，目前没有有效的治疗方法，并且是在发展中国家引起腹泻病的最常见病原体之一。 在前一个资助期的努力集中在一个独特的双功能酶胸苷酸脱氢酶-二氢叶酸还原酶（TS-DHFR），发现只有在原生动物病原体作为抑制剂设计的可能的分子靶点。这些在人隐孢子虫（Ch）TS-DHFR中的概念验证研究已经确定了这种双功能酶中独特的物种特异性和变构/非活性靶区域，突变分析和机理研究已经验证了这些位点对于催化功能至关重要。PI实验室及其合作者开发了一种独特而成功的计算和机械引导方法，用于发现ChTS-DHFR的新抑制剂。这种计算和详细的实验方法的伙伴关系是一个独特的策略，建立最佳的理化和药理学参数的设计。然后对这些分子进行实验测试，并通过机械，结构和细胞评估迭代地完善设计。结合结构分析的分子对接和虚拟筛选已经发现了CH TS-DHFR的新型抑制剂，包括一些在细胞培养中具有纳摩尔效力和抗隐孢子虫活性的抑制剂。目前的资助期将集中在铅优化和寄生虫药物输送的新纳米技术战略，以开发治疗隐孢子虫感染的新疗法。

 DESCRIPTION (provided by applicant): The World Health Organization estimated that at the end of 2012 over 35 million individuals were infected with HIV-1 (Human Immunodeficiency Virus). Due to the advancements in highly active antiretroviral (HAART) therapy the number of AIDS-related deaths has been reduced and individuals are living longer. Despite successes with HAART, opportunistic infections remain one of major causes of death in AIDS patients. Among the most prevalent is the protozoal parasite pathogen, Cryptosporidium. Cryptosporidiosis is one of the AIDS- defining illnesses characterized by a severe chronic diarrhea for which there are currently no effective therapies and among the most frequent pathogens causing diarrheal diseases in developing countries. Efforts during the previous grant period have focused on a unique bifunctional enzyme thymidylate synthase-dihydrofolate reductase (TS-DHFR) found only in protozoal pathogens as a possible molecular target for inhibitor design. These proof of concept studies in Cryptosporidium hominis (Ch)TS-DHFR have identified unique species specific and allosteric/non-active target regions in this bifunctional enzymes and mutational analysis and mechanistic studies have validated these sites as essential for catalytic function. The PIs lab and their collaborators have developed a distinctive and successful computationally and mechanistically guided approach for the discovery of new inhibitors of ChTS-DHFR. This partnership of computational and detailed experimental methodologies is a unique strategy that builds optimal physiochemical and pharmacological parameters into the design. These molecules are then experimentally tested and the design iteratively refined through mechanistic, structural and cellular evaluation. Molecular docking and virtual screening coupled with structural analyses have discovered novel inhibitors of CH TS-DHFR including some with nanomolar potency and anti-Cryptosporidial activity in cell culture. The current grant period will focus on lead optimization and a novel nanotechnology strategy for parasite drug delivery to develop new therapies to treat Cryptosporidial infections.