Prevalence of point mutations in the dihydrofolate reductase and dihydropteroate synthetase genes of Plasmodium falciparum isolates from India and Thailand:: a molecular epidemiologic study
Prevalence of point mutations in the dihydrofolate reductase and dihydropteroate synthetase genes of Plasmodium falciparum isolates from India and Thailand:: a molecular epidemiologic study
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DOI：
10.1046/j.1365-3156.2000.00632.x
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发表时间：
2000-10-01
影响因子：
3.3
通讯作者：
Lal, AA
中科院分区：
文献类型：
--
作者：
Biswas, S;Escalante, A;Lal, AA
乙胺嘧啶-磺胺嘧啶（PS）被用作氯喹无效的恶性疟原虫疟疾患者的二线治疗。对这些药物的耐药性已被证明与二氢叶酸还原酶（DHFR）和二氢蝶酸合成酶（DHPS）基因的点突变编码。我们的目的是评估发生在DHFR和DHPS基因之间的恶性疟原虫分离株的点突变的比较率从印度和泰国的PS的使用是在一个不同的速度。我们使用突变特异性聚合酶链反应（PCR）技术和突变特异性限制性消化来确定DHFR和DHPS基因突变的发生率，分别在密码子16，51，59，108，164和436，437，581和613。在来自印度的89个临床分离株中，在DHFR基因的情况下，我们发现71个S108 N型，10个N51 I型，28个C59 R型和4个I164 L型。在来自泰国的50株分离株中，DHFR基因的点突变率在四个密码子位置处较高。其中S108 N型47例，N51 I型18例，C59 R型23例，I164 L型12例。来自这两个国家的分离株均不具有成对突变S108 T和A16 V。印度分离株DHPS基因突变频率较低：4.5%的分离株出现DHPS基因突变，其中S436 F、A437 G、A613 T各2例，S436 F、A613 T各2例;而66%（33/50）的泰国分离株在密码子436、437、581和613处发生突变，其中S436 F突变13例，A437 G突变15例，A581 G突变19例，A613 S/T突变25例，从单突变型到四突变型。在印度分离株中，DHFR点突变非常频繁，85/89株具有野生型DHPS遗传特征。来自泰国的样本中的突变模式是不同的，因为大多数与DHFR和DHPS基因的点突变有关。
Pyrimethamine-sulfadoxine (PS) is used as a second-line treatment for P. falciparum malaria patients who fail to respond to chloroquine. Resistance to these drugs has been shown to encode with point mutations in dihydrofolate reductase (DHFR) and dihydropteroate synthetase (DHPS) genes. Our aim was to assess the comparative rate of point mutation occurring in DHFR and DHPS genes among P. falciparum isolates from India and Thailand where the use of PS is at a different rate. We used the mutation-specific polymerase chain reaction (PCR) technique and mutation-specific restriction digestion to determine the prevalence of DHFR and DHPS gene mutations at codons 16, 51, 59, 108, 164 and at 436, 437, 581 and 613, respectively. In the 89 clinical isolates from India, in the case of the DHFR gene, we found 71 of S108N, 10 of N51I, 28 of C59R and four of I164L types. Among the 50 isolates from Thailand the rate of point mutations in the DHFR gene was higher at four codon positions. We found 47 of S108N, 18 of N51I, 23 of C59R and 12 of I164L types. None of the isolates from either country possessed the paired mutations S108T and A16V. Mutations of the DHPS gene were less frequent among the Indian isolates: 4.5% showed DHPS gene mutation, two of S436F, A437G, A613T and two of S436F, A613T; whereas 66% (33/50) of the Thai isolates had mutated at codons 436, 437, 581 and 613 which include 13 of S436F, 15 of A437G, 19 of A581G and 25 of A613S/T, ranging from single to quadruple mutant types. Among the Indian isolates, DHFR point mutations were very frequent and 85/89 had a wild type DHPS genetic profile. The pattern of mutations in the samples from Thailand was different, as most were associated with point mutations in DHFR and DHPS genes.