Malaria variant surface antigen expression and vulnerability to disease in Malian children with Hemoglobin C trait

项目摘要 2015年，疟疾在撒哈拉以南非洲造成29.2万名5岁以下儿童死亡。血红蛋白 提供预防疟疾的保护，并反映疟疾对人类的强大选择力， 基因组在马里农村，血红蛋白C性状提供了对严重疟疾的保护， 疟疾病保护具有血红蛋白C特征的儿童免受疟疾疾病的确切机制是 尚不清楚，但似乎与恶性疟原虫疟疾寄生虫表面的变异抗原有关。 感染的红细胞在介导疾病严重程度中起关键作用。这些变异的表面抗原结合 宿主受体在内皮细胞膜，促进组织隔离和避免脾 间隙婴儿和幼儿对恶性疟原虫疟疾的自然免疫力可能 这取决于针对这些变体表面抗原的保护性抗体应答的发展。 血红蛋白C特性减少了这些抗原在感染红细胞表面的数量，并改变了这些抗原在感染红细胞表面的表达。 他们的展示。我们发现，具有血红蛋白C性状的马里儿童对血红蛋白C的血清识别能力降低， 与野生型儿童相比，变异表面抗原，表明异常表达的变异表面抗原 抗原限制抗体反应。我们假设，在人类中， 儿童血红蛋白C性状是寄生虫变异表面抗原的一个子集的异常表达。 识别这些异常表达的变异表面抗原可能会产生一个疟疾蛋白质的子集， 疾病的发病机理。利用新的转录组学和蛋白基因组学技术，我们的目标是确定 在血红蛋白阳性儿童感染中转录本（Aim 1）和表达的变异表面抗原（Aim 2） AC，AA和AS在最近的马里农村疟疾发病率纵向研究中。我们将识别转录 以及这些组之间的变异表面抗原的表达差异， 无症状疟疾发作。然后，我们将测量这些变异表面的血清反应性如何变化 在这些人群中，有症状的感染与无症状的感染（目标3）后， 蛋白质微阵列，这样我们就可以将疾病的脆弱性与变异的表面抗原表达联系起来。的 我们的研究的贡献将是确定变异的表面抗原转录在有症状的， 马里儿童血红蛋白AC、AA和AS的无症状感染;存在变异表面抗原 在这些感染中，感染红细胞表面上的差异;以及对不同表面的血清反应性差异 抗原我们的方法将确定血红蛋白C性状的影响是否发生在转录或蛋白质 表达并转运至红细胞表面。我们的最终目标是确定一个子集的变异 疟疾疫苗的表面抗原表位，以保护免受临床疾病。完成后，我们将 制备以精确地绘制和定义变异体对临床疟疾的天然保护的表位 被鉴定为对疾病发病机理和血红蛋白C性状保护至关重要的表面抗原。

PROJECT SUMMARY In 2015, malaria killed 292,000 children under five years of age in sub-Saharan Africa. Hemoglobinopathies provide protection against malarial disease and reflect the powerful selective force of malaria on the human genome. In rural Mali, hemoglobin C trait provides protection against severe malaria and uncomplicated malaria illness. The precise mechanisms that protect children with hemoglobin C trait against malaria illness is unclear, but appear to be linked to Plasmodium falciparum malaria parasite variant antigens on the surface of infected erythrocytes that play a critical role in mediating disease severity. These variant surface antigens bind to host receptors in the endothelial membrane, facilitating tissue sequestration and avoidance of splenic clearance. The natural acquisition of immunity to P. falciparum malaria in infants and young children likely depends on the development of protective antibody responses against these variant surface antigens. Hemoglobin C trait decreases the quantity of these antigens on the surface of infected erythrocytes and alters their display. We have found that Malian children with hemoglobin C trait have reduced serorecognition of variant surface antigens compared to wild type children, suggesting that abnormally expressed variant surface antigens limit the antibody response. We hypothesize that a primary protective mechanism against malaria in children with Hemoglobin C trait is abnormal expression of a subset of parasite variant surface antigens. Identifying these abnormally expressed variant surface antigens may yield a subset of malaria proteins critical to disease pathogenesis. Using novel transcriptomic and proteogenomic techniques, we aim to identify the transcripts (Aim 1) and expressed variant surface antigens (Aim 2) in infections in children with hemoglobin AC, AA, and AS in a recent longitudinal study of malaria incidence in rural Mali. We will identify transcription and expression differences in variant surface antigens between these groups with respect to clinical and asymptomatic malaria episodes. We will then measure how seroreactivity changes to these variant surface antigens following a symptomatic versus an asymptomatic infection in these groups (Aim 3) with a custom protein microarray so that we can link disease vulnerability with variant surface antigen expression. The contributions of our research will be to identify variant surface antigen transcripts in symptomatic and asymptomatic infections of Malian children with hemoglobin AC, AA, and AS; variant surface antigens present on the surface of infected erythrocytes in these infections; and differences in seroreactivity to variant surface antigens. Our approach will determine if the effects of hemoglobin C trait occur during transcription or protein expression and translocation to the erythrocyte surface. Our ultimate goal is to identify a subset of variant surface antigen epitopes for a malaria vaccine to protect against clinical disease. Upon completion, we will be prepared to precisely map and define epitopes underlying natural protection to clinical malaria for the variant surface antigens identified as critical to disease pathogenesis and hemoglobin C trait protection.