Molecular epidemiology of malaria in Cameroon.: XVIII.: Polymorphisms of the Plasmodium falciparum merozoite surface antigen-2 gene in isolates from symptomatic patients
Molecular epidemiology of malaria in Cameroon.: XVIII.: Polymorphisms of the Plasmodium falciparum merozoite surface antigen-2 gene in isolates from symptomatic patients
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DOI：
10.4269/ajtmh.2004.70.238
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发表时间：
2004-03-01
影响因子：
3.3
通讯作者：
Escalante, A
中科院分区：
文献类型：
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作者：
Basco, LK;Tahar, R;Escalante, A
Merozoite surface antigen-2 （MSA-2）是一种多态遗传标记，对恶性疟原虫野外分离物具有高度歧视性。通过等位基因特异性聚合酶链反应和扩增产物的直接测序，分析了从喀麦隆雅温得有症状患者中获得的分离株的遗传多样性。137株分离物中，25株（18%）仅存在fc27型等位基因，40株（29%）仅存在3d7型等位基因，72株（53%）存在同时存在两种等位基因的寄生群体。295个片段中，145个（49.2%）属于FC27等位基因，150个（50.8%）属于3D7等位基因。共有23个不同的MSA-2等位基因（10个fc27型和13个3d7型，在多次感染中产生44种不同的组合）。DNA测序显示不同的个体序列。属于FC27等位基因家族的序列相对保守，大部分多态性源于重复单元数的差异。相比之下，3D7等位基因家族中富含gsa区域的序列保守性较差，但喀麦隆分离株中的许多序列已经在地理上遥远的其他分离株中被鉴定出来。我们的研究结果显示，MSA-2的中心区域在大小、等位基因家族、多重感染中这两个特征的组合以及喀麦隆雅温得恶性疟原虫临床分离株复杂种群结构背后的序列变化方面存在广泛的多样性。
Merozoite surface antigen-2 (MSA-2) is a polymorphic genetic marker that is highly discriminatory for characterizing Plasmodium falcipariatt field isolates. Genetic diversity of isolates obtained from symptomatic patients residing in Yaounde, Cameroon was analyzed by an allele-specific polymerase chain reaction and direct sequencing of amplification products. Of 137 isolates, 25 (18%) had only FC27-type alleles, 40 (29%) had only 3D7-type alleles, and 72 (53%) had multiple parasite populations with both alleles. Of 295 fragments, 145 (49.2%) and 150 (50.8%) belonged to FC27 and 3D7 alleles, respectively. There were 23 different MSA-2 alleles (10 FC27-type and 13 3D7-type that yielded 44 different combinations in multiple infections). DNA sequencing showed distinct individual sequences. Sequences belonging to the FC27 allelic family were relatively conserved, with most of the polymorphism arising from differences in the number of repeat units. In contrast, the sequences within the GSA-rich region in 3D7 allelic family were less conserved, but many of the sequences in Cameroonian isolates have been identified in other isolates from geographically distant origins. Our results show an extensive diversity of the central region of MSA-2 in size, allelic family, combinations of these two features in multiple infections, and sequence variations underlying the complex population structure of P. falciparum clinical isolates in Yaounde, Cameroon.