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

项目总结 2015年，在撒哈拉以南非洲，疟疾导致29.2万名5岁以下儿童死亡。血红蛋白病 预防疟疾，反映疟疾对人类的强大选择性 基因组。在马里农村，血红蛋白C特征提供了对严重疟疾的保护，而且不复杂 疟疾。保护具有血红蛋白C特征的儿童免受疟疾疾病侵袭的确切机制是 不清楚，但似乎与恶性疟原虫表面的疟疾寄生虫变异抗原有关 感染的红细胞在调节疾病严重程度方面起着关键作用。这些变异的表面抗原结合在一起 在内皮细胞膜上寄主受体，促进组织隔离和避免脾 通行证。婴幼儿可能自然获得对恶性疟原虫的免疫力 取决于针对这些不同表面抗原的保护性抗体反应的发展。 血红蛋白C特性减少了感染红细胞表面这些抗原的数量，并改变了 他们的展示。我们发现，具有血红蛋白C特征的马里儿童降低了对 变异型表面抗原与野生型儿童比较，提示异常表达变异型表面 抗原限制了抗体的反应。我们假设对疟疾的主要保护机制是 儿童血红蛋白C的特征是异常表达寄生虫表面抗原的一个亚群。 识别这些异常表达的变异表面抗原可能会产生关键的疟疾蛋白子集 对疾病发病机制的研究。利用新的转录组和蛋白质组学技术，我们的目标是识别 转录本(Aim 1)和表达的变异表面抗原(Aim 2)在儿童血红蛋白感染中的作用 AC、AA和AS在最近一项马里农村疟疾发病率的纵向研究中。我们将确定转录 以及这些组之间不同表面抗原在临床和临床上的表达差异 无症状的疟疾发作。然后我们将测量这些不同表面的血清反应性如何变化 这些组中有症状感染后的抗原与无症状感染后的抗原(目标3) 蛋白质微阵列，这样我们就可以将疾病的脆弱性与不同的表面抗原表达联系起来。这个 我们的研究的贡献将是在有症状的和 马里儿童的无症状感染与血红蛋白AC、AA和AS；存在不同的表面抗原 这些感染的红细胞表面对变异表面的血清反应性的差异 抗原。我们的方法将确定血红蛋白C特性的影响是发生在转录过程中还是发生在蛋白质过程中 表达和转位到红细胞表面。我们的最终目标是识别变种的子集 疟疾疫苗的表面抗原表位用于预防临床疾病。建成后，我们将 准备精确绘制和定义变种疟疾的自然保护基础表位 表面抗原被认为是疾病发病机制和血红蛋白C特性保护的关键。

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.