Multiplex analysis of IgA and IgG antibody responses to early childhood malaria infections to inform vaccine development

摘要 尽管经过几十年的努力，疟疾仍然是全球发病和死亡的原因， 疟疾是恶性疟原虫造成的最大负担，主要影响撒哈拉以南非洲的幼儿。 世界卫生组织最近批准了一种疟疾疫苗;但是， 疫苗是必要的，而且可能是根除疟疾所必需的。不幸的是，我们对 对疟疾的保护性免疫仍然有限。在人类宿主体内，寄生虫通过几个 在各个器官中的生命周期阶段，在每个阶段表达大量抗原，其中许多抗原保留下来， 没有特征的为了增加挑战，许多表面暴露的抗原都镶嵌着氨基酸， 多态性导致免疫系统逃避，一些表位引起免疫应答， 实际上是保护。多种遗传多样性抗原的血清分析将提高我们对 对疟疾的保护性免疫，并推动更好疫苗的设计。有限的注意力被给予 疟疾抗体反应的同种型组成，伊加，虽然以前认识不足，似乎 成为一个重要的组成部分。虽然大多数血清分析研究检查抗体对整个蛋白质的反应， 对包含蛋白质的肽的抗体应答的研究允许识别精确的抗体 蛋白质表面的结合位点，这可以为疫苗设计提供信息。本研究将重点关注伊加和IgG 两组人对疟疾感染的抗体反应：（1）生活在西非马里的婴儿和儿童， （2）生活在南部非洲马拉维的婴儿，他们被随访了三到四年。 出生到两岁。这两组人都处于疟疾传播率高的环境中，并进行了主动和被动的治疗 监测疟疾感染。抗体对代表数百种恶性疟原虫的肽的反应性 包括抗原变体在内的蛋白质将在首次和重复疟疾感染后测量， PepSeq是一种新的肽库平台，以前从未用于疟疾。识别的表位 将确定疟疾感染后的血清伊加和IgG，纵向研究设计将允许 研究疟疾抗体应答的幅度、动力学和同种型比（伊加/IgG）。总的来说， 这项工作将回答有关伊加对疟疾感染的反应的关键问题，确定表位， 蛋白质作为疫苗候选抗原进行探索，并提供关于抗体反应的新数据， 抗原变体。总的来说，这些发现将提高我们对疟疾免疫反应的理解， 为疫苗设计提供信息。

ABSTRACT Despite decades of eradication efforts, malaria remains a global cause of morbidity and mortality, with the greatest burden caused by Plasmodium falciparum and largely affecting young children in Sub-Saharan Africa. One malaria vaccine has recently been approved by the World Health Organization; however, improved vaccines are needed and are likely essential for malaria eradication. Unfortunately, our understanding of protective immunity to malaria remains limited. Within the human host, the parasite propagates through several life cycle stages in various organs, expressing multitudes of antigens at each stage, many of which remain uncharacterized. To add to the challenge, many surface-exposed antigens are studded with amino acid polymorphisms that result in immune system evasion, and some epitopes elicit immune responses that are not actually protective. Serum profiling of multiple genetically diverse antigens will improve our understanding of protective immunity to malaria and drive the design of better vaccines. Limited attention has been given to isotype composition of the antibody response to malaria, and IgA, though previously underrecognized, appears to be a prominent component. While most seroprofiling studies examine antibody responses to whole proteins, study of antibody responses to peptides that comprise the proteins allows for discernment of precise antibody binding sites on the protein surface, which can inform vaccine design. This research will focus on IgA and IgG antibody responses to malaria infection in two groups: (1) infants and children living in Mali, West Africa who were followed for three to four years and (2) infants living in Malawi, Southern Africa, who were followed from birth to two years. Both groups were in settings with high malaria transmission and had active and passive surveillance for malaria infections. Antibody reactivity to peptides representing hundreds of P. falciparum proteins including antigenic variants will be measured following first and repeated malaria infections on PepSeq, a novel peptide library platform that has not previously been used in malaria. Epitopes recognized by serum IgA and IgG after malaria infection will be identified, and a longitudinal study design will allow for the study of the magnitude, kinetics, and isotype ratio (IgA/IgG) of the antibody response to malaria. In summary, this work will answer critical questions about the IgA response to malaria infection, identify epitopes and proteins for exploration as vaccine candidate antigens, and provide new data on the antibody response to antigenic variants. Overall, the findings will improve our understanding of the immune response to malaria and inform vaccine design.