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由周围性基质(PM)排列，PM由甲壳素骨架组成 它组装了各种糖胺多聚糖和蛋白质。PM在节肢动物中起到防御作用 通过保护它们的中肠上皮免受研磨的食物颗粒的影响，调节摄入的毒素的运动，以及 作为防止病原体感染的物理屏障。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沙蝇传播的利什曼原虫，它们分泌的几丁质酶可以 降解PM相关的甲壳素。然而，采采蝇传播的非洲锥虫不产生几丁质酶， 而这些寄生虫用来绕过采采氏PM的机制(S)也鲜为人知。 除了可能感染非洲锥虫外，所有采采蝇在分类上都有一种 内共生细菌的可变群落。锥虫通过采采期传播的成功 媒介在一定程度上取决于苍蝇和这些细菌之间的生理相互作用。采采人的一张 在所有实验室定植的苍蝇中，内共生菌都表现出均匀的分布。 以及野生苍蝇种群内和种群之间的异质性分布。几个独立的字段和 基于实验室的研究一再证明，存在与密度之间存在正相关关系 采采人中肠中的苏丹红和锥虫成功地在苍蝇体内建立感染的能力。这个 这种关联背后的机制从未被确定过。在这项应用中，我们的跨学科 研究小组将解决这样的假设，即苏打草分泌的内切几丁质酶能降解几丁质 采采人PM的中坚力量我们推测，钠介导的PM相关甲壳素的降解有助于 锥虫感染的建立有两种方式。首先，这一过程将损害结构的完整性 从而使锥虫更容易穿越。第二，甲壳素的分解代谢导致产物 N-乙酰-D-氨基葡萄糖，它是一种有效的杀锥虫凝集素的抑制剂。我们建议使用苏丹斯突变体 不能产生内切酶来从功能上表征细菌、 采采蝇的PM，以及苍蝇中肠内锥虫感染的机构。此外，我们建议使用field 捕捉采采蝇以确定它们的苏打是否产生内切酶来调节结构完整性 他们的采采赛主持人的下午完成本申请中提出的实验将增加我们的 了解锥虫传播的基本生理机制。 Tsetse载体，并可能对开发新的疾病控制具有翻译意义 战略。此外，本文所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、扁虱、沙蝇)寄生中肠相关细菌，并具有病原体必须 为了传播给新的脊椎动物宿主而进行杂交。