Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States.
Oak Ridge Institute for Science and Education, U.S. Department of Energy, Oak Ridge, TN, United States.
Front Immunol. 2023 Aug 24;14:1208822. doi: 10.3389/fimmu.2023.1208822. eCollection 2023.
malaria is a leading cause of child mortality in Nigeria. Neonates are born with maternal antibodies from placental transfer which may protect against malaria infection in the first months of life. The IgG dynamics of the transition from passively transferred antimalarial antibodies to actively acquired IgG from natural exposure have not been well elucidated.
Blood samples collected during a 2018 Nigeria nationwide HIV/AIDS household survey were available for 9,443 children under 5 years of age, with a subset of infants under 2 months of age having maternal samples available (n=41). Samples were assayed for the HRP2 antigen and anti-malarial IgG antibodies. LOESS regression examined the dynamics in IgG response in the first 5 years of life. Correlation with maternal IgG levels was assessed for mother/child pairs.
Consistent decreases were observed in median IgG levels against all spp. antigen targets for the first months of life. At a population level, apical membrane antigen-1 (AMA1) and merozoite surface protein-1 19kD (PfMSP1) IgG decreased during the first 12 months of life before reaching a nadir, whereas IgGs to other targets only declined for the first 4 months of life. Seropositivity showed a similar decline with the lowest seropositivity against AMA1 and PfMSP1 at 10-12 months, though remaining above 50% during the first 2 years of life in higher transmission areas. No protective association was observed between IgG positivity and infection in infants. Maternal antibody levels showed a strong positive correlation with infant antibody levels for all antigens from birth to 2 months of age, but this correlation was lost by 6 months of age.
Maternally transferred anti-malarial IgG antibodies rapidly decline during the first 6 months of life, with variations among specific antigens and malaria transmission intensity. From 3-23 months of age, there was a wide range in IgG levels for the blood-stage antigens indicating high individual variation in antibody production as children are infected with malaria. Non- species-specific antigens showed similar patterns in waning immunity and correlation with paired mother's IgG levels compared to antigens.
疟疾是尼日利亚儿童死亡的主要原因。新生儿从胎盘转移中获得母体抗体，这可能在生命的头几个月内保护他们免受疟疾感染。从被动转移的抗疟抗体到自然暴露产生的主动获得的 IgG 的过渡过程中的 IgG 动力学尚未得到很好的阐明。
在 2018 年尼日利亚全国艾滋病毒/艾滋病家庭调查期间收集的血液样本可用于 9443 名 5 岁以下儿童，其中一部分 2 个月以下的婴儿有母亲样本（n=41）。样本检测 HRP2 抗原和抗疟 IgG 抗体。局部加权回归分析（LOESS）用于研究生命前 5 年 IgG 反应的动态。评估母亲/儿童对的相关性与母体 IgG 水平。
在生命的头几个月，所有 spp.抗原靶标针对 IgG 水平均呈一致下降。在人群水平上，顶膜抗原-1（AMA1）和裂殖体表面蛋白-1 19kD（PfMSP1）IgG 在生命的前 12 个月下降，然后达到最低点，而其他靶标的 IgG 仅在生命的前 4 个月下降。血清阳性率也呈下降趋势，AMA1 和 PfMSP1 的血清阳性率最低，在 10-12 个月，而在高传播地区，生命的前 2 年内仍保持在 50%以上。在婴儿中，未观察到 IgG 阳性与 感染之间存在保护关联。从出生到 2 个月，母体抗体水平与所有抗原的婴儿抗体水平呈强烈正相关，但在 6 个月时相关性丧失。
在生命的前 6 个月内，母体抗疟 IgG 抗体迅速下降，具体抗原和疟疾传播强度存在差异。从 3-23 个月龄，血液期抗原的 IgG 水平差异很大，表明儿童感染疟疾时抗体产生的个体差异很大。非特异性抗原在免疫衰减和与配对母亲 IgG 水平的相关性方面表现出与 抗原相似的模式。
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