Plasmodium ovale hypnozoite development and relapse: a coordinated in vivo in vitro study

卵形疟原虫休眠子的发育和复发：体内体外协调研究

• 批准号: 10304203
• 负责人: John H Adams
• 金额: $ 17.68万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-11-17 至 2024-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10304203
• 关键词: Accounting; Address; Africa; Aminoquinolines; Anemia; Anopheles gambiae; Antibodies; Antimalarials; Area; Asia; Biological Assay; Biology; Blood; Cessation of life; Child; Chronic; Clinical; Cohort Studies; Country; Cryopreservation; Culicidae; Data; Detection; Development; Enrollment; Entomology; Epidemiology; Exhibits; Florida; Frequencies; Funding; Gabon; Genetic Variation; Genotype; Health; Hepatocyte; Hospitalization; Human; Image; Immunity; In Vitro; Incidence; Individual; Infection; Intervention; Liver; Malaria; Malaria Diagnostic; Measures; Meiosis; Methods; Minority; Modeling; Molecular; North Carolina; Parasites; Patients; Pattern; Persons; Pharmaceutical Preparations; Phenotype; Plasmodium; Plasmodium falciparum; Plasmodium ovale; Plasmodium vivax; Play; Prevalence; Primaquine; Prospective Studies; Recurrence; Regimen; Relapse; Research Personnel; Science; Ships; Siblings; Site; Sleep; South America; Sporozoites; Tanzania; Testing; Time; Universities; Variant; Vivax Malaria; Work; deep sequencing; design; drug development; epidemiologic data; experimental study; feeding; follow-up; in vivo; malaria transmission; molecular diagnostics; neglect; neglected tropical diseases; novel; prevent; recurrent infection; targeted sequencing; tool; volunteer

ABSTRACT Malaria control interventions focused on P. falciparum are not adequate to address the growing burden of non- falciparum species, especially those malaria species that cause relapse. Plasmodium ovale, like P. vivax, causes recurrent infections arising from hypnozoites in the liver. Hypnozoites “sleeping” in the liver before they reactivate to cause relapse are invisible to malaria diagnostics and impervious to first-line ACT regimens. Thus they likely play a key role in the rising number of P. ovale cases across Africa, estimated to exceed 15 million cases each year. Almost nothing is known about P. ovale hypnozoites and their relapse patterns. We have only recently learned that P. ovale in fact comprises two non-recombining species - P. ovale curtisi and P. ovale wallikeri. Interestingly, these two species may exhibit distinct relapse patterns, suggesting species- specific hypnozoite biology. However, the little evidence available regarding the two species’ relapse patterns is confusing: epidemiologic data in travelers suggest that P.o. wallikeri relapses occur at shorter intervals, but the first prospective study of P. ovale in Africa only found relapses due to P.o. curtisi, not wallikeri. We aim to resolve this question by examining in vivo relapse phenotypes for both species as well as directly measuring hypnozoite commitment in vitro. We hypothesize that both P. ovale curtisi and wallikeri develop hypnozoites and relapse in a species-specific manner. To test our hypothesis, we will deploy tools built to study P. vivax. Using targeted sequencing methods designed to distinguish relapses from re-infections in endemic settings developed by investigators at the University of North Carolina, and a state-of-the-art 384-well primary human hepatocyte platform for studying Plasmodium liver stages developed at the University of South Florida, we will 1) Conduct an observational cohort study to define species-specific relapse rates of P.o. curtisi and wallikeri and 2) Establish a liver stage model for P. ovale to evaluate hypnozoite commitment in both species. We will conduct the fieldwork for this proposal within the framework of a larger R01-funded malaria transmission study in Bagamoyo, Tanzania. This will allow us to leverage the significant molecular and entomologic capacity we have developed there, where we have already successfully infected Anopheles gambiae mosquitoes with P.ovale. In partnership with the Muhimbili University of Health and Allied Sciences, we will identify 40 volunteers with qPCR-positive P. ovale infection, follow them every 2 weeks to genotype any recurrences that occur over 8-12 months, and conduct mosquito feeding assays to generate 15-20 P. ovale sporozoite isolates using blood-fed mosquitoes from the same volunteers. Cryopreserved infectious sporozoites will be shipped to the USF, where liver-stage experiments will be performed to measure hypnozoite commitment (the ratio of developing schizonts to small-form hypnozoites) and to test anti- hypnozoite drugs. This study will establish the first liver-stage model of P. ovale. Findings will crucially inform the development of drugs and strategies to achieve the elimination of all malaria, not just P. falciparum.

抽象的 针对恶性疟原虫的疟疾控制干预措施不足以解决非 - 恶性物种，尤其是那些引起救济的疟疾物种。卵子疟原虫，如P. vivax， 引起肝脏中催眠症的复发感染。肝脏在肝脏中“睡觉”之前 重新激活以救济是疟疾诊断的看不见的，并且对一线ACT方案无关。那 他们可能在非洲的椭圆形案例数量增加中发挥着关键作用，估计超过1500万 每年案件。关于椭圆形的催眠症及其退休模式，几乎一无所知。我们有 直到最近才得知，卵孢菌实际上包括两个非重组物种-P。ovale Curtisi和P. 椭圆形的Walllikeri。有趣的是，这两个物种可能表现出不同的继电器模式，表明规格 - 特定的催眠生物学。但是，关于这两个物种退休模式的几乎没有证据 令人困惑的是：旅行者的流行病学数据表明P.O. walllikeri继电器以较短的间隔发生，但 对非洲卵卵的首次前瞻性研究仅发现是由于P.O的复发。柯蒂西，不是walllikeri。我们的目标 通过检查物种的体内缓解表型来解决这个问题，并直接测量 体外催眠症承诺。我们假设P. ovale Curtisi和Walllikeri都在发展 以特定方式的方式进行催眠和继电器。为了检验我们的假设，我们将部署构建的工具 研究P. Vivax。使用旨在区分继电器与重新感染的目标测序方法 北卡罗来纳大学的调查人员开发的内在环境和最先进的384孔 主要人类肝细胞平台用于研究南部大学疟原虫阶段 佛罗里达，我们将进行1）进行观察队列研究，以定义P.O.的规格特异性继电器率。柯蒂西 和walllikeri和2）建立肝阶段模型，以评估两者中的催眠症的承诺 物种。我们将在较大的R01资助的疟疾的框架内进行该提案的实地考察 坦桑尼亚Bagamoyo的传输研究。这将使我们能够利用重要的分子和 我们在那里开发的昆虫学能力，我们已经成功地感染了动脉群 冈比亚蚊子和p.ovale。与Muhimbili卫生大学和盟友科学大学合作， 我们将确定40位患有QPCR阳性卵巢感染的志愿者，每2周跟随他们进行基因型 发生在8-12个月以上的复发，并进行蚊子喂养测定15-20P。 使用来自同一志愿者的血液喂养蚊子分离孢子。冷冻保存感染力 Sporozoites将运送到USF，将进行肝脏阶段实验以测量 催眠症症（发展中的精神分裂症与小型催眠者的比率），并测试抗抗菌 催眠药。这项研究将建立椭圆形假单胞菌的第一个肝阶段模型。调查结果将基于克鲁克利 告知制定药物和策略以消除所有疟疾，而不仅仅是恶性疟原虫。