Host Immune Responses to Antigens of Malaria Parasites

宿主对疟疾寄生虫抗原的免疫反应

• 批准号: 7964636
• 负责人: Carole Long
• 金额: $ 54.42万
• 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/7964636
• 关键词: Adult; Africa; Age; Agonist; Alhydrogel; Antibodies; Antibody Formation; Antigens; Antimalarials; Area; Binding; Biological Assay; Blood; CD4 Positive T Lymphocytes; Cell surface; Cells; Child; Chondroitin Sulfate A; Clinical Research; Clinical Trials; Collaborations; Complex; DNA; Development; Disease; Disease Resistance; Drug Formulations; Epitopes; Erythrocytes; Ethnic group; Family; Foundations; Genetic Polymorphism; Genotype; Goals; Growth; HIV; Hemoglobin; Human; Immune response; Immune system; Immunity; Immunization; Immunoglobulin G; Immunologics; In Vitro; Infection; Inflammation; Intervention; Laboratories; Libraries; Life; Longitudinal Studies; Malaria; Mali; Memory; Modeling; Mus; Parasites; Pathology; Pattern; Placenta; Plasma; Population; Pregnancy; Preparation; Proteins; Resistance development; Rodent; Rodent Model; Role; Sampling; Series; Specificity; Staging; Staining method; Stains; Structure; Surface; T memory cell; T-Lymphocyte; T-Lymphocyte Subsets; Technology; Testing; Vaccines; aptamer; cohort; cytokine; genetic variant; insight; mouse model; next generation; novel; polyclonal antibody; prevent; research study; response; successful intervention; tool; vaccine candidate; volunteer

While it is clear that children and adults living in endemic areas do develop resistance to this disease, albeit slowly, the mechanisms responsible for this are not well understood. In 2009 the Long laboratory built upon the foundation established in the previous year to explore the interface between the malaria parasite and the hosts immune system. To accomplish this we have employed both clinical research studies in Mali and several different rodent models of malaria infection. To develop the clinical research, we have collaborated with Dr. Rick Fairhurst of LMVR and Dr. Mahamadou Diakite of the MRTC in Mali to continue a longitudinal study of 1300 children of various ages in 3 villages in Mali. This study was initiated in 2008 and will continue for 5 years so that we can construct a comprehensive picture of the development of adaptive immune responses in children in this malarious area of Mali. A subset of these children is being followed for detailed T cell responses and development of humoral immune responses. In addition, all children have been typed for a series of hemoglobin and red cell polymorphisms by the Fairhurst laboratory; even from the first year of analysis it is already apparent that children with HbS genotype are protected against malaria in this population. We believe that these genetic variants provide a unique window into the acquisition of anti-malarial immunity and are pursuing the hypothesis that comparison of the immune responses of HbS children with other children lacking this genotype will allow us to identify factors that make a major contribution to this protection. We have tested paired plasma samples from the 2008 subset of Malian children against a series of blood stage parasite proteins and these results are being analyzed and compared with those from a larger cohort of children selected in 2009. Similarly we have determined antibody titers to a range of parasite antigens in adults from 3 different ethnic groups - the Malinke, Dogon and Fulani. As a counterpart we are also studying the functional activity of these antibodies we have also tested the activity of purified IgG from these populations in a standardized in vitro parasite growth inhibition assay. We have also continued to refine the analysis of different human CD4+ T cell subsets including T memory cells and multifunctional T cells. We took advantage of the availability of cells from naive vaccine volunteers in the US to develop analytic tools such as intracellular cytokine staining of T cells specific for various blood-stage parasite antigens. We have completed analysis of a clinical trial of the blood-stage antigen PfAMA1 in naive volunteers employing Alhydrogel with CPG to assess the impact of addition of a TLR9 agonist to this formulation. We then extended our analysis of malaria-specific memory T cells to adults and children in Mali, identifying AMA1 specific memory cells in adults in Mali. We are also continuing some studies in mice using rodent malaria parasites to examine the role of multifunctional CD4+ T cells in protective responses after immunization with specific malaria proteins. We are also testing some novel blood stage vaccine candidates in these models and testing various immunologic effector functions. We have also made significant progress in 2 new areas for the laboratory. The first is the immunologic analysis of antibody responses to the DBL3X domain of the VAR2CSA protein. This PfEMP1 domain, whose structure was determined by Dr. Kavita Singh, has been implicated in pregnancy associated malaria through binding to chondroitin sulfate A in the placenta. In collaboration with Dr. Singh we have produced monoclonal and polyclonal antibodies to this domain and showed that both can recognize the surface of CSA-selected parasitized red cells. We have also shown that antibodies can inhibit the binding of parasitized erythrocytes to CSA. The second new project involves the application of aptamers to search for conserved antigenic determinants on the surface of malaria infected erythrocytes. We have prepared complex DNA aptamer libraries and conducted a series of selections on various targets. The selected preparations are now being sequenced using next generation technology and we are confirming reactivity of different aptamer families on red cell surfaces.

虽然很明显，居住在地方性地区的儿童和成年人确实会对这种疾病产生抗药性，尽管缓慢，但对此负责的机制尚不清楚。 2009年，长期实验室建立在上一年建立的基金会基础上，旨在探索疟原虫和宿主免疫系统之间的界面。为了实现这一目标，我们已经在马里进行了临床研究和疟疾感染的几种不同啮齿动物模型。 为了开发临床研究，我们与LMVR的Rick Fairhurst博士和马里MRTC的Mahamadou Diakite博士合作，继续对马里3个村庄的1300名各个年龄的儿童进行纵向研究。这项研究于2008年启动，将持续5年，以便我们可以全面了解马里这个疟疾地区儿童适应性免疫反应的发展。这些儿童的一部分被遵循详细的T细胞反应和体液免疫反应的发展。此外，Fairhurst实验室已将所有儿童用于一系列血红蛋白和红细胞多态性。即使从分析的第一年开始，已经很明显，患有HBS基因型的儿童在该人群中受到疟疾的保护。我们认为，这些遗传变异为获得抗疟疾免疫的获取提供了独特的窗口，并正在追求以下假设：比较HBS儿童与其他缺乏这种基因型的儿童的免疫反应的比较将使我们能够识别为这种保护做出重大贡献的因素。 我们已经测试了来自2008年马里儿童子集的配对等离子体样品与一系列血液阶段寄生虫蛋白的测试，并且正在分析这些结果，并将这些结果与2009年选择的较大儿童的同类群体进行了比较。同样，我们确定了来自3个不同族裔的成人范围的抗体滴度。作为对应物，我们还研究了这些抗体的功能活性，我们还通过标准化的体外寄生虫生长抑制测定法测试了这些群体纯化IgG的活性。 我们还继续完善对包括T记忆细胞和多功能T细胞在内的不同人类CD4+ T细胞子集的分析。我们利用了美国幼稚疫苗志愿者的细胞可用性，以开发分析工具，例如针对各种血液阶段寄生虫抗原的T细胞的细胞内细胞因子染色。我们已经完成了对使用Alhydrogel使用CPG的幼稚志愿者中血液阶段抗原PFAMA1的临床试验的分析，以评估添加TLR9激动剂对此表述的影响。然后，我们将对疟疾特异性记忆T细胞的分析扩展到马里的成年人和儿童，鉴定了MALI成年人的AMA1特定记忆细胞。 我们还使用啮齿动物疟疾寄生虫在小鼠中继续进行一些研究，以检查用特定疟疾蛋白免疫后多功能CD4+ T细胞在保护性反应中的作用。我们还正在测试这些模型中一些新型血液阶段疫苗的候选物，并测试各种免疫效应子功能。 我们还在实验室的两个新领域取得了重大进展。首先是对VAR2CSA蛋白DBL3X结构域的抗体反应的免疫学分析。该PFEMP1结构域的结构由Kavita Singh博士确定，与妊娠有关疟疾与胎盘中的硫酸软骨素A的结合有关。与Singh博士合作，我们已经与该结构域生产了单克隆和多克隆抗体，并表明两者都可以识别CSA选择的寄生红细胞的表面。我们还表明，抗体可以抑制寄生的红细胞与CSA的结合。 第二个新项目涉及适用器在疟疾感染的红细胞表面上寻找保守的抗原决定因素。我们已经准备了复杂的DNA适体库，并在各种目标上进行了一系列选择。现在，使用下一代技术对所选的制剂进行了测序，我们正在确认红细胞表面上不同适体家族的反应性。