Investigation of a shipworm endosymbiont compound with activity against the AIDS-associated pathogens Cryptosporidium and Toxoplasma

 性状（由申请方提供）：隐孢子虫属和弓形虫是机会性顶复体寄生虫，其在免疫功能低下的人中引起显著的发病率和死亡率。治疗这些寄生虫的新疗法是医学上的当务之急。我们已经确定了一种由软体动物共生细菌产生的化合物，它可以抑制C。parvum和T.对宿主细胞无毒性。 船蛆是一种海洋双壳类软体动物，它们会钻入并贪婪地消耗木材。与大多数食木动物一样，船蛆在共生细菌的帮助下消化木材，但在船蛆中，共生体被安置在鳃细胞内，并将纤维素分解酶从细菌空泡中输出，从宿主细胞中输出，并进入盲肠腔，在那里它们影响船蛆木质食物的消化。尽管营养丰富的环境，但船蛆盲肠缺乏细菌群落，这表明存在有效的抗菌化合物。已显示出船虫共生体在体内产生抗微生物的次级代谢产物，并且这些化合物可能在维持盲肠的几乎无菌的环境中发挥作用。我们发现，船蛆鳃内共生菌，特纳氏端杆菌，产生一种化合物，抑制胞内生长的C。parvum和T.在体外以nM水平抑制弓形虫，并抑制C.小鼠细小病毒感染。该化合物也对相关的血寄生虫牛Bababeliobovis有活性，表明对顶复门有广泛的疗效。在本申请中，我们将测试该化合物靶向T. gondii和C. parvum，并且该活性在体内有效。为了验证这一假设，我们提出了以下具体目标： 1A -识别T。gondii和C.共生体化合物靶向的细小病毒感染过程。我们将评估共生体化合物对特定寄生虫过程的影响，并测试该化合物对其他顶复门的影响，包括II型T。弓形虫速殖子和缓殖子。 目的1B -鉴定C中共生体化合物活性的靶标。parvum和T.刚地。我们将采用遗传和生物化学方法来鉴定这种化合物靶向的基因产物。 目的1C -评价共生体化合物对鼠C.细小病毒感染 这些实验为今后的靶点验证、构效关系、药代动力学和药效学评价以及在其他动物模型中的药效试验奠定了基础。parvum和T.弓形虫感染以前从未研究过船虫共生体产生抗寄生虫化合物的潜力。因此，这些研究具有巨大的潜力，可以开辟抗寄生虫药物发现的新领域，为药物开发提供新的分子靶点，可能广泛应用于许多难治性病原体。

 DESCRIPTION (provided by applicant): Cryptosporidium spp. and Toxoplasma gondii are opportunistic apicomplexan parasites that cause significant morbidity and mortality in immunocompromised people. New therapeutics to treat these parasites are a medical imperative. We have identified a compound produced by a mollusk symbiotic bacterium that inhibits intracellular growth of C. parvum and T. gondii without toxicity to the host cell. Shipworms are marine bivalve mollusks that burrow into and voraciously consume wood. Like most xylophagous animals, shipworms digest wood with the assistance of their symbiotic bacteria but in shipworms, the symbionts are housed within the cells of the gill and export cellulolytic enzymes out of the bacterial vacuole, out of the host cell, and into the lumen of the caecum where they effect digestion of the shipworm's woody diet. Despite the nutrient rich environment, the shipworm caecum lacks a bacterial community suggesting the presence of potent anti-microbial compounds. Shipworm symbionts have been shown to produce anti-microbial secondary metabolites in vivo and it is likely these compounds play a role in maintaining the nearly sterile environment of the caecum. We found that the shipworm gill endosymbiont, Teredinibacter turnerae, produces a compound that inhibits intracellular growth of C. parvum and T. gondii at nM levels in vitro and inhibits C. parvum infection in mice. This compound is also active against the related hemoparasite, Babesia bovis, suggesting a broad efficacy against apicomplexans. In this application, we will test the hypothesis that this compound targets a gene product or process common to T. gondii and C. parvum, and that this activity is effective in vivo. To test this hypothesis, we propose the following specific aim: Aim 1A - Identify the T. gondii and C. parvum infection processes targeted by the symbiont compound. We will evaluate the effect of the symbiont compound on specific parasite processes and test the compound against other apicomplexans, including Type II T. gondii tachyzoites and bradyzoites. Aim 1B - Identify the target of the symbiont compound's activity in C. parvum and T. gondii. We will employ both genetic and biochemical approaches to identify the gene products targeted by this compound. Aim 1C - Evaluate the efficacy of the symbiont compound against murine C. parvum infection. These experiments will provide the foundation for future studies involving target verification, structure-activity relationships, pharmacokinetic-pharmacodynamic evaluation and tests of efficacy in other animal models of C. parvum and T. gondii infection. Shipworm symbionts have never before been investigated for their potential to produce anti-parasitic compounds. Thus, these studies have tremendous potential to open up a new area of anti-parasitic drug discovery, holding the promise of new molecular targets for drug development, potentially with broad application to many intractable pathogens.