CROSS-REACTIVE ASPARAGINE-RICH DETERMINANTS SHARED BETWEEN SEVERAL BLOOD-STAGE ANTIGENS OF PLASMODIUM-FALCIPARUM AND THE CIRCUMSPOROZOITE PROTEIN
CROSS-REACTIVE ASPARAGINE-RICH DETERMINANTS SHARED BETWEEN SEVERAL BLOOD-STAGE ANTIGENS OF PLASMODIUM-FALCIPARUM AND THE CIRCUMSPOROZOITE PROTEIN
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DOI：
10.1016/0166-6851(90)90085-z
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发表时间：
1990-04-01
影响因子：
1.5
通讯作者：
REESE, RT
中科院分区：
文献类型：
--
作者：
ARDESHIR, F;HOWARD, RF;REESE, RT
从恶性疟原虫cDNA表达文库来自mRNA的无性血液阶段，我们分离和测序5个不同的cDNA克隆，其预测的蛋白质产物是异常丰富的天冬酰胺（Asn）。其中两个克隆R5和G5分别含有基于Asn-Asn-Thr（NNT）和Asn-Asn-Met（NNM）的串联不完全重复序列。其他三个，E4，C5和R13，以及G5，含有长度从2到26个残基不等的聚天冬酰胺段。以各cDNA序列为探针的DNA印迹实验结果表明，5个克隆中的每一个对应于不同的恶性疟原虫基因。由cDNA克隆表达的恶性疟原虫蛋白片段共享存在于多种恶性疟原虫蛋白上的交叉反应性抗原决定簇。在免疫印迹实验中，选择用于结合由克隆E4、C5或G5表达的多肽的猫头鹰猴抗体与来自所有5个克隆的表达的蛋白质以及与来自嗜酸性粒细胞感染的红细胞的至少10种蛋白质反应。交叉反应性表位可以通过两种富含Asn的肽结构来建模：（1）（NNT）8，其序列基于R5重复;和（2）（NPNA）6，其序列基于恶性疟原虫环子孢子蛋白（CSP）的富含Asn的重复。从从未暴露于子孢子的免疫猴的血清中选择与每种肽结合的抗体。所选抗体结合所有5种表达的蛋白质免疫印迹分析，并且还结合来自寄生红细胞的几种蛋白质。CSP重复单元和几种血液阶段抗原之间的这种交叉反应性以前没有报道过。
From a Plasmodium falciparum cDNA expression library derived from mRNA of the asexual blood stages, we isolated and sequenced five different cDNA clones whose predicted protein products were unusually rich in asparagine (Asn). Two of the clones, R5 and G5, contain tandem imperfectly repeated sequences based on Asn-Asn-Thr (NNT) and Asn-Asn-Met (NNM) respectively. The other three, E4, C5 and R13, as well as G5, contain stretches of polyasparagine varying in length from 2 to 26 residues. Results of DNA blotting experiments with the individual cDNA sequences as probes suggest that each of the five clones corresponds to a different P. falciparum gene. The fragments of P. falciparum proteins expressed by the cDNA clones shared crossreactive antigenic determinants which were present on multiple P. falciparum proteins. In immunoblotting experiments, owl monkey antibodies selected for binding to the polypeptide expressed by clone E4, C5 or G5 reacted with the expressed proteins from all 5 clones, and with at least 10 proteins from schizont infected erythrocytes. The cross-reactive epitopes could be modeled by two Asn-rich peptide structures: (1) (NNT)8, whose sequence was based on the R5 repeat; and (2) (NPNA)6, whose sequence was based on the Asn-rich repeat of the P. falciparum circumsporozoite protein (CSP). Antibodies that bound to each peptide were selected from sera of immune monkeys that had never been exposed to sporozoites. The selected antibodies bound all 5 expressed proteins immunoblotting assays and also bound to several proteins from parasitized erythrocytes. Such cross reactivity between the CSP repeating unit and several blood-stage antigens has not been previously reported.