Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana.
Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America.
PLoS One. 2021 Sep 10;16(9):e0257219. doi: 10.1371/journal.pone.0257219. eCollection 2021.
Antigen polymorphisms in essential malarial antigens are a key challenge to the design and development of broadly effective malaria vaccines. The effect of polymorphisms on antibody responses is fairly well studied while much fewer studies have assessed this for T cell responses. This study investigated the effect of allelic polymorphisms in the malarial antigen apical membrane antigen 1 (AMA1) on ex vivo T cell-specific IFN-γ responses in subjects with lifelong exposure to malaria. Human leukocyte antigen (HLA) class I-restricted peptides from the 3D7 clone AMA1 were bioinformatically predicted and those with variant amino acid positions used to select corresponding allelic sequences from the 7G8, FVO, FC27 and tm284 parasite strains. A total of 91 AMA1 9-10mer peptides from the five parasite strains were identified, synthesized, grouped into 42 allele sets and used to stimulate PBMCs from seven HLA class 1-typed subjects in IFN-γ ELISpot assays. PBMCs from four of the seven subjects (57%) made positive responses to 18 peptides within 12 allele sets. Fifty percent of the 18 positive peptides were from the 3D7 parasite variant. Amino acid substitutions that were associated with IFN-γ response abrogation were more frequently found at positions 1 and 6 of the tested peptides, but substitutions did not show a clear pattern of association with response abrogation. Thus, while we show some evidence of polymorphisms affecting T cell response induction, other factors including TCR recognition of HLA-peptide complexes may also be at play.
疟原虫主要抗原的抗原多态性是设计和开发广泛有效的疟疾疫苗的一个关键挑战。多态性对抗体反应的影响已得到相当充分的研究,而对 T 细胞反应的研究则少得多。本研究调查了疟原虫抗原顶膜抗原 1(AMA1)中的等位基因多态性对终身暴露于疟疾的受试者体外 T 细胞特异性 IFN-γ反应的影响。通过生物信息学预测了 3D7 克隆 AMA1 的 HLA Ⅰ类限制肽,并使用这些预测的肽来选择来自 7G8、FVO、FC27 和 tm284 寄生虫株的相应等位基因序列。从五个寄生虫株中鉴定出总共 91 个 AMA1 9-10 位氨基酸肽,将其分为 42 个等位基因组,并用于 IFN-γ ELISpot 测定中刺激来自七个 HLA Ⅰ类基因分型的个体的 PBMC。来自七个个体中的四个(57%)对 12 个等位基因组中的 18 个肽产生了阳性反应。在 18 个阳性肽中,有 50%来自 3D7 寄生虫变异株。与 IFN-γ 反应阻断相关的氨基酸取代更频繁地出现在测试肽的第 1 位和第 6 位,但取代并没有表现出与反应阻断明显相关的模式。因此,虽然我们有一些证据表明多态性影响 T 细胞反应的诱导,但其他因素,包括 TCR 对 HLA-肽复合物的识别,也可能在起作用。
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