Endosymbiont mediated chitin catabolism in the tsetse fly gut impacts trypanosome transmission

采采蝇肠道内共生介导的几丁质分解代谢影响锥虫传播

• 批准号: 10572879
• 负责人: BRIAN L WEISS
• 金额: $ 26.37万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-11-07 至 2024-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10572879
• 关键词: African; Animals; Arthropod Vectors; Arthropods; Bacteria; Biological Models; Catabolism; Chitin; Chitinase; Chromosomes; Communities; Culicidae; Data; Development; Disease; Disease Vectors; Environment; Enzymes; Epidemiology; Epithelium; Exhibits; Food; Genes; Genetic; Genome; Geography; Glucosamine; Glycosaminoglycans; Goals; Human; In Vitro; Infection; Ingestion; Interdisciplinary Study; Investigation; Kenya; Knock-out; Knowledge; Laboratories; Learning; Lectin; Leishmania; Mediating; Midgut; Modeling; Movement; Musca domestica; Outcome; Parasites; Pathogenicity; Periodicity; Phlebotominae; Physiological; Physiology; Plasmodium; Population; Prevalence; Process; Production; Proteins; Research; Role; Salivary Glands; Sand Flies; Structure; Symbiosis; Taxonomy; Ticks; Toxin; Trypanocidal Agents; Trypanosoma; Trypanosoma brucei brucei; Tsetse Flies; Vertebral column; Work; density; disorder control; endosymbiont; experimental study; extracellular; fly; inhibitor; insight; migration; mutant; novel; novel strategies; overexpression; particle; pathogen; socioeconomics; success; transmission process; vector; vector competence; vector-borne

The midgut of most arthropods is lined by a peritrophic matrix (PM) that is composed of a chitin backbone upon which assemble a variety of glycosaminoglycans and proteins. The PM serves a defensive role within arthropods by protecting their midgut epithelia from abrasive food particles, regulating the movement of ingested toxins, and serving as a physical barrier against pathogen infection establishment. Some vector-borne protozoan pathogens, including mosquito-transmitted Plasmodium and sand fly-transmitted Leishmania, secrete chitinases that can degrade PM-associated chitin. However, tsetse fly-transmitted African trypanosomes do not produce chitinase, and the mechanism(s) these parasites use to circumvent tsetse’s PM are poorly understood. In addition to potentially being infected with African trypanosomes, all tsetse flies harbor a taxonomically variable community of endosymbiotic bacteria. The success of trypanosome transmission through the tsetse vector depends in part on physiological interactions between the fly and these bacteria. One of tsetse’s endosymbionts, Sodalis glossinidius, exhibits a homogeneous distribution within all laboratory colonized flies and a heterogeneous distribution within and between wild fly populations. Several independent field and laboratory-based studies have repeatedly demonstrated a positive correlation between the presence and density of Sodalis in tsetse’s midgut and the ability of trypanosomes to successfully establish an infection in the fly. The mechanisms that underlie this correlation have never been determined. In this application our interdisciplinary research team will address the hypothesis that a Sodalis secreted endochitinase degrades the chitinous backbone of tsetse’s PM. We speculate that Sodalis-mediated degradation of PM-associated chitin facilitates trypanosome infection establishment in two ways. First, this process would compromise the structural integrity of the PM, thus making it easier for trypanosomes to cross. Second, chitin catabolism results in the production of N-acetyl-D-glucosamine, which is a potent inhibitor of trypanocidal lectins. We propose to use Sodalis mutants that cannot produce endochitinase to functionally characterize the tripartite relationship between the bacterium, tsetse’s PM, and trypanosome infection establishment in the fly’s midgut. Additionally, we propose to use field captured tsetse flies to determine if their Sodalis produce endochitinase that mediates the structural integrity of their tsetse host’s PM. Completion of the experiments proposed in this application will increase our understanding of the basic physiological mechanisms that mediated trypanosome transmission through the tsetse vector and may have translational implications towards the development of novel disease control strategies. Additionally, knowledge obtained herein will be applicable to other arthropod vector model systems (e.g., mosquitoes, ticks, sandflies) that house midgut-associated bacteria and have a PM that pathogens must cross in order to be transmitted to a new vertebrate host.

大多数节肢动物的中肠内衬有围食基质（PM），该基质由几丁质骨架组成 它组装各种糖胺聚糖和蛋白质。 PM 在节肢动物中发挥防御作用 通过保护中肠上皮免受磨蚀性食物颗粒的侵害，调节摄入毒素的运动，以及 作为防止病原体感染建立的物理屏障。一些媒介传播的原生动物病原体， 包括蚊子传播的疟原虫和白蛉传播的利什曼原虫，分泌几丁质酶，可以 降解 PM 相关的几丁质。然而，采采蝇传播的非洲锥虫不产生几丁质酶， 人们对这些寄生虫用来规避采采蝇 PM 的机制知之甚少。 除了可能感染非洲锥虫之外，所有采采蝇都具有分类学特征 内共生细菌的可变群落。锥虫通过采采蝇传播的成功 载体部分取决于苍蝇和这些细菌之间的生理相互作用。采采蝇之一 内共生体 Sodalis gloseninidius 在所有实验室定植果蝇中表现出均匀分布 以及野蝇种群内部和种群之间的异质分布。多个独立领域和 基于实验室的研究多次证明存在与密度之间呈正相关 采采蝇中肠中索达利斯的存在以及锥虫在果蝇中成功感染的能力。这 这种相关性背后的机制尚未确定。在此应用程序中，我们的跨学科 研究小组将解决 Sodalis 分泌的内切几丁质酶降解几丁质的假设 采采PM的骨干。我们推测 Sodalis 介导的 PM 相关几丁质的降解促进了 锥虫感染的建立有两种方式。首先，这个过程会损害结构完整性 PM，从而使锥虫更容易穿过。二、甲壳素分解代谢导致产生 N-乙酰基-D-葡萄糖胺，它是杀锥虫凝集素的有效抑制剂。我们建议使用 Sodalis 突变体 不能产生内切几丁质酶来功能性地表征细菌之间的三方关系， 采采蝇的 PM，以及苍蝇中肠中锥虫感染的建立。此外，我们建议使用 field 捕获采采蝇以确定它们的 Sodalis 是否产生介导结构完整性的内切壳多糖酶 他们的采采蝇宿主的 PM。完成本申请中提出的实验将增加我们的 了解介导锥虫传播的基本生理机制 采采蝇载体，可能对新型疾病控制的发展具有转化意义 策略。此外，本文获得的知识将适用于其他节肢动物矢量模型系统 （例如，蚊子、蜱虫、白蛉）栖息着中肠相关细菌，并且具有病原体必须具有的 PM 杂交以传播到新的脊椎动物宿主。