Mali International Center for Excellence in Research: Parasitic Infectious Diseases and their Vectors

马里国际卓越研究中心：寄生虫传染病及其媒介

• 批准号: 10014151
• 负责人: Carole Long
• 金额: $ 113.2万
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10014151
• 关键词: 5 year old; Address; Adolescent; Affect; Affinity; Africa; Africa South of the Sahara; African; Age; Altitude; Antibodies; Antigens; Arbovirus Infections; Area; Arthropods; Bacteria; Biological Assay; Biological Availability; Biology; Blood; Breeding; Burkina Faso; Cell Survival; Centers of Research Excellence; Child; Clinical; Clinical Protocols; Clinical Trials; Collaborations; Communicable Diseases; Complex; Culicidae; DNA; Data; Detection; Diagnosis; Disease; Disease Vectors; Ecology; Education; Endemic Diseases; Environmental Wind; Epidemiology; Erythrocytes; Erythropoiesis; Evaluation; Faculty; Female; Finding of Mean Corpuscular Hemoglobin; Gender; Gene Dosage; Genetic; Genomic DNA; Genotype; Globin; Goals; Habitats; Helium; Hemoglobin; Hemolysis; Heterogeneity; Human; Immunity; Immunology; Individual; Infection; Insecta; Integration Host Factors; Intervention; Iron; Kinetics; Knowledge; Laboratories; Leishmania; Life Cycle Stages; Linear Regressions; Location; Malaria; Mali; Measurement; Measures; Medical; Messenger RNA; Metabolic; Methods; Microscope; Modeling; Molecular; Monitor; National Institute of Allergy and Infectious Disease; Natural Selections; Niger; Oral Medicine; Organism; Oxygen; Parasites; Parasitic Diseases; Pathology; Pharmacy facility; Phlebotominae; Plasmodium; Plasmodium falciparum; Plasmodium vivax; Population; Predisposition; Prevalence; Proteins; Publications; Rain; Reading; Refractory; Reporting; Research; Research Personnel; Research Training; Residual state; Reverse Transcriptase Polymerase Chain Reaction; Rivers; Sampling; Science; Scientist; Seasonal Variations; Seasons; Security; Sickle Cell; Sickle Cell Anemia; Site; Slide; Sporozoites; Surveys; Techniques; Technology; Testing; Time; Training; Travel; Universities; Virus; Water; Wolbachia; Work; alpha Globin; asexual; base; beta Globin; boys; clinical risk; co-infection; cohort; density; genetic variant; girls; in vivo; indexing; individual response; international center; malaria transmission; medical schools; member; meter; migration; programs; protein complex; screening; sickling; transmission process; vaccine candidate; vaccine trial; vector; vector control; vector mosquito; volunteer

Dry Season Ecology of Malaria Vectors Our work continues to focus on: (1) Windborne long-range migration of mosquitoes as strategies of vector and malaria persistence in the Sahel, and (2) Mosquito dormancy (aestivation) through the dry season to account for the persistence of A. coluzzii . Building on previous results, we have amassed additional compelling evidence that A. coluzzii (previously, the M form of A. gambiae) persists locally by aestivation whereas A. gambiae (previously, the S form) and A. arabiensis re-colonize the area after the onset of rains. To explain the long-distance migration our project combines (i) on-the-ground monitoring of vector density and composition along 9 surveillance villages, spanning over 400 km, with (ii) aerial sampling (40-250 meters above ground) of mosquitoes using traps tethered to helium filled balloons. We continue to work on identification of the mosquitoes and many other insects that are caught in these high-altitude traps; to date this analysis has established the first report of wind-assisted long-distance migration of malaria vectors. These findings have important implications for malaria control and for the understanding and modeling of malaria transmission. Impact of Iron Availability on Sickling Kinetics in Malian Children To address the Impact of iron availability on sickling kinetics in Malian Children, our specific aims are to: Assess alpha globin gene copy number and iron bioavailability; examine the distribution of intracellular hemoglobin concentration (mean corpuscular hemoglobin concentration, MCHC) and related RBC parameters; measure hemoglobin composition and oxygen affinity: quantify sickling kinetics of fresh RBCs ex vivo using an automated microscope; and determine rates of hemolysis and red cell turnover in vivo. Together, these measurements will provide the first comprehensive evaluation of naturally existing heterogeneity of hemoglobin composition in the red blood cell and its impact on the kinetics of sickling. Malaria Transmission Transmission of malaria is a critical aspect of the parasite life cycle but is poorly understood, and we have increased our efforts to investigate parasite sexual stages, malaria transmission in the field, and the biology of the mosquito vector. In May of 2014 we completed a clinical protocol studying 500 individuals of all ages in Kenieroba (13-I-N107). Examining more than 10,000 samples adn using sensitive molecular methods rather than slide reading, we found that a relatively high proportion of individuals of all ages carry malaria parasites: prevalence was highest in November of 2013 during the wet season and lowest in May of 2014. Unlike most studies, we assessed longitudinal prevalence of parasites in the population and by a linear regression model, only age and gender showed significant effects on the longitudinal prevalence (p<0.0001 and p=0.0008, respectively), while other host factors did not. We showed for the first time that increasing P. falciparum longitudinal prevalence throughout the year was associated with decreasing risk of clinical malaria. This suggests that those with persistent parasite carriage acquire stronger protective immunity against clinical malaria. Using the parasite DNA barcoding technique and have found that most individuals in Kenieroba carry more than one clone of P. falciparum and that this distribution does not change from the wet season to the dry season. Further, using RT-PCR to test for gametocyte mRNA encoding Pfs25, we have determined that 50-80% of people that harbor parasite DNA also have detectable gametocytes throughout the year, showing that no one group can be uniquely targeted for interventions to reduce transmission. Screening of Malian Cohort for Antibodies to Asexual Stage Antigens We have also used the samples derived from the Malian cohort to study the responses of individuals to one of the major blood stage vaccine candidates PfRh5 and other proteins in its complex. This complex is critical for invasion of host red blood cells and promising clinical trial results have recently become available (S. Draper et al.). We have quantitated antibodies to PfRH5 and other complex proteins in Malians of various ages and established that the concentrations of anti-PfRh5 antibodies are far lower (100x less) than has been seen in a vaccine study in nave volunteers from the UK. The basis for this is not clear given the extensive exposure of the Malians but this is important information as a prelude to clinical trials in the field with members of this complex. Naturally Occurring Wolbachia in Anopheline Mosquitoes from Mali Wolbachia is a bacterium commonly found in arthropods that is known to reduce susceptibility of culicine mosquitoes to several Arboviral infections. Anopheline mosquitoes were thought to be naturally refractory to Wolbachia infection. However, we identified a naturally-occurring strain of Wolbachia in An. gambiae s.l. mosquitoes in the Malian villages of Kenieroba and Dangassa, different from strains previously identified in Burkina Faso. Field and laboratory data indicate that Wolbachia infection reduces the prevalence and intensity of sporozoite infection. We carried out experimental P. falciparum infections and found that Wolbachia does not affect the early stages of Plasmodium in the mosquito, but the prevalence and intensity of sporozoite infection was significantly reduced in females infected with Wolbachia (see PNAD publication). More recently we have trained a Malian investigator to do genomic DNA extractions from field-caught desiccated mosquitoes, and we have optimized a new single-PCR detection assay to detect Wolbachia. We will examine the seasonal variation in prevalence of infection in Kenieroba and Dangassa and survey other villages in the area to establish the range of distribution of Wolbachia in this region, as well as different larval habitats, to establish whether Wolbachia infection is widespread or limited to specific larval breeding sites. Leishmania in Mali Leishmania is another parasitic disease endemic to Mali. We have examined the impact of malaria control measures such as long-lived be nets and indoor residual spraying, showing that these interventions also impact sandflies and Leishmania infection. We have also done a study of the co-endemicity of filarial and Leishmania infections in different settings in Mali. The presence of the two infections transmitted by mosquitoes and sandflies makes integrated vector control very important in areas like these.

疟疾媒介的旱季生态 我们的工作继续关注：（1）蚊子作为向量和疟疾在萨赫勒的持续存在的策略，以及（2）蚊子休眠（美化）到干旱季节，以说明A. coluzzii的持久性。在先前的结果的基础上，我们积累了其他令人信服的证据，表明A. coluzzii（以前是A. gambiae的M形式）通过审核局部持续存在，而A. gambiae（以前是S形式）和Arabiensis在降雨开始后重新殖民区域。 为了解释长距离迁移，我们的项目结合了沿9个监视村庄的矢量密度和成分的（i）跨越400公里的地面监测，（ii）使用浮球上的捕集圈捕集的蚊子（ii）空中采样（地面40-250米）的蚊子。我们继续致力于鉴定蚊子和许多其他昆虫，这些昆虫被这些高空陷阱捕获。迄今为止，该分析已建立了疟疾媒介的风辅助长距离迁移的第一项报告。这些发现对疟疾的控制以及对疟疾传播的理解和建模具有重要意义。 铁的可用性对马里儿童疾病动力学的影响 为了解决铁的可用性对马里儿童疾病动力学的影响，我们的具体目的是：评估alpha globin基因拷贝数和铁生物利用度；检查细胞内血红蛋白浓度（平均红细胞血红蛋白浓度，MCHC）和相关RBC参数的分布；测量血红蛋白组成和氧亲和力：使用自动显微镜量化新鲜RBC的寒假动力学；并确定体内溶血和红细胞更新的速率。 总之，这些测量结果将对红细胞中血红蛋白组成的自然异质性进行首次全面评估及其对疾病动力学的影响。 疟疾传播 疟疾的传播是寄生虫生命周期的关键方面，但知之甚少，我们增加了研究寄生虫性阶段，田间传播的疟疾以及蚊子载体的生物学的努力。 2014年5月，我们完成了一项临床方案，研究了肯尼奥巴（Kenieroba）所有年龄段的500个人（13-I-N107）。 Examining more than 10,000 samples adn using sensitive molecular methods rather than slide reading, we found that a relatively high proportion of individuals of all ages carry malaria parasites: prevalence was highest in November of 2013 during the wet season and lowest in May of 2014. Unlike most studies, we assessed longitudinal prevalence of parasites in the population and by a linear regression model, only age and gender showed significant effects on the longitudinal患病率（分别为p <0.0001和p = 0.0008），而其他宿主因素没有。我们首次表明，全年恶性疟原虫的纵向患病率增加与临床疟疾风险降低有关。这表明那些持续的寄生虫托架的人可以对临床疟疾获得更强的保护性免疫。 使用寄生虫DNA条形码技术，并发现肯尼奥巴（Kenieroba）的大多数人都携带多个恶性疟原虫的克隆，并且这种分布从潮湿季节到旱季不会变化。此外，使用RT-PCR测试编码PFS25的配子细胞mRNA，我们已经确定有50-80％的寄生虫DNA的人在一年中也具有可检测到的配子细胞，这表明没有人可以唯一针对干预措施来减少传播。 筛选马里人队列的无性阶段抗原抗体 我们还使用了源自马里队的样品来研究个体对综合体中主要血液阶段疫苗PFRH5和其他蛋白质的反应。这种复合物对于侵袭宿主红细胞至关重要，最近有前途的临床试验结果可用（S. Draper等人）。我们在各个年龄的马利亚人中有针对PFRH5和其他复合蛋白的定量抗体，并确定抗PFRH5抗体的浓度远低于英国豪华志愿者中的疫苗研究中所见的抗体（100倍）。考虑到马里人的广泛暴露，这一点尚不清楚，但这是与该综合体成员一起在该领域进行临床试验的序幕的重要信息。 马里的蚊子蚊子中天然发生的沃尔巴氏菌 沃尔巴奇（Wolbachia）是一种在节肢动物中发现的细菌，已知可降低库氏蚊对几种弧菌感染的敏感性。蚊子被认为天然对沃尔巴奇感染是耐火的。但是，我们确定了An中的沃尔巴氏菌的自然菌株。冈比亚S.L. Kenieroba和Dangassa的马里村中的蚊子与以前在Burkina Faso中发现的菌株不同。 现场和实验室数据表明，沃尔巴氏菌感染降低了孢子岩感染的患病率和强度。我们进行了实验性恶性疟原虫感染，发现沃尔巴氏菌不会影响蚊子中疟原虫的早期阶段，但是在感染沃尔巴氏菌的女性中，孢子岩感染的患病率和强度显着降低（见PNAD出版）。 最近，我们培训了一名马里研究者，从现场捕获的蚊子进行基因组DNA提取，并优化了一种新的单PCR检测测定法以检测沃尔巴奇。 我们将研究Kenieroba和Dangassa感染的季节性变化，并调查该地区的其他村庄，以确定该地区Wolbachia的分布范围，以及不同的幼虫栖息地，以确定Wolbachia感染是广泛的还是限于特定幼虫繁殖地。 利什曼尼亚在马里 利什曼原虫是马里特有的另一种寄生疾病。我们已经检查了疟疾控制措施的影响，例如长寿命为网和室内残留喷涂，表明这些干预措施还影响了沙蝇和利什曼原虫感染。我们还研究了马里不同环境中丝状和利什曼原虫感染的共同性。蚊子和沙氟传播的两种感染的存在使整合的载体控制在此类地区非常重要。