de Pécoulas P E, Tahar R, Ouatas T, Mazabraud A, Basco L K
Centre de Génétique Moléculaire, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France.
Mol Biochem Parasitol. 1998 May 1;92(2):265-73. doi: 10.1016/s0166-6851(97)00247-8.
The gene encoding dihydrofolate reductase-thymidylate synthase of the human malaria parasite, Plasmodium vivax, was isolated by polymerase chain reaction from genomic DNA and cloned. The sequences of the dihydrofolate reductase domain of 30 clinical isolates originating from various geographic areas were compared. Interstrain analysis revealed several genotypic variations, including short tandem repeat arrays which produced length polymorphism between different parasite isolates and point mutations in the putative dihydrofolate reductase active site cavity corresponding to those associated with pyrimethamine resistance in P. falciparum and rodent malaria parasites. Amino acid substitutions Ser-->Asn-117 and Ser-->Arg-58 were associated with decreased level of in vitro pyrimethamine sensitivity. These findings suggest that the P. vivax dihydrofolate reductase domain is characterized by polymorphism that has not been observed in P. falciparum and may explain the resistance of some P. vivax isolates to pyrimethamine. Nucleotide sequence data reported in this paper are available in the EMBL, GenBank and DDJB databases under the accession numbers X98123 (isolate ARI/Pakistan), AJ003050 (isolate CNC/Thailand), AJ003051 (isolate COU/unknown geographic origin), AJ003052 (isolate DUF/French Guiana), AJ003053 (isolate GRO/Madagascar), AJ003054 (isolate HRT/Comoros Islands), AJ003071 (isolate LFT/Cambodia), AJ003072 (isolate LGF/'India), AJ003073 (isolate MAN/Comoros Islands), AJ003074 (isolate MAT/Surinam), AJ003075 (isolate PHI/Djibouti), AJ003076 (isolate PIT/Madagascar), AJ003077 (isolate YTZ/Indonesia), AJ222630 (isolate Burma-1), AJ222631 (isolate Burma-151), AJ222632 (isolate Burma-5), AJ222633 (isolate Burma-6), AJ222634 (isolate Burma-98).
通过聚合酶链反应从基因组DNA中分离并克隆了人类疟原虫间日疟原虫编码二氢叶酸还原酶-胸苷酸合成酶的基因。比较了来自不同地理区域的30个临床分离株的二氢叶酸还原酶结构域的序列。菌株间分析揭示了几种基因型变异，包括短串联重复序列阵列，其在不同寄生虫分离株之间产生长度多态性，以及在假定的二氢叶酸还原酶活性位点腔中的点突变，这些突变与恶性疟原虫和啮齿类疟原虫中与乙胺嘧啶抗性相关的突变相对应。氨基酸取代Ser→Asn-117和Ser→Arg-58与体外乙胺嘧啶敏感性水平降低有关。这些发现表明，间日疟原虫二氢叶酸还原酶结构域具有多态性，这在恶性疟原虫中未观察到，并且可能解释了一些间日疟原虫分离株对乙胺嘧啶的抗性。本文报道的核苷酸序列数据可在EMBL、GenBank和DDJB数据库中获得，登录号分别为X98123（分离株ARI/巴基斯坦）、AJ003050（分离株CNC/泰国）、AJ003051（分离株COU/未知地理来源）、AJ003052（分离株DUF/法属圭亚那）、AJ003053（分离株GRO/马达加斯加）、AJ003054（分离株HRT/科摩罗群岛）、AJ003071（分离株LFT/柬埔寨）、AJ003072（分离株LGF/印度）、AJ003073（分离株MAN/科摩罗群岛）、AJ003074（分离株MAT/苏里南）、AJ003075（分离株PHI/吉布提）、AJ003076（分离株PIT/马达加斯加）、AJ003077（分离株YTZ/印度尼西亚）、AJ222630（分离株Burma-1）、AJ222631（分离株Burma-151）、AJ222632（分离株Burma-5）、AJ222633（分离株Burma-6）、AJ222634（分离株Burma-98）。
