Polymorphism in pfcrt and pfmdr1 genes of malaria parasite populations in South-East countries

抗药性疟原虫的出现和传播是疟疾防治的主要障碍。我们分析了东南亚国家、越南、缅甸和印度尼西亚的恶性疟原虫pfcrt和pfmdr 1基因的遗传多态性。各国分离株的基因型多态性具有一定的特点。越南样本中的pfcrt基因多为氯喹敏感基因型，且敏感型的比例近年来有增加的趋势。另一方面，所有来自印度尼西亚的pfcrt基因都含有Thr 76，这是氯喹抗性所必需的。这两个国家的样本对氯喹的效果非常有意义;在越南，氯喹已多年不用于治疗恶性疟原虫，而在印度尼西亚，氯喹仍是首选治疗药物。缅甸分离株中有多种类型的pfcrt和pfmdr 1基因，患者能够获得几种不同的药物进行治疗。基因型分析表明，不同地区的药物对疟原虫的选择作用基本相同，各国疟原虫的多态性差异可能是药物对每个病人疟原虫的累积效应，这种效应以基因型的比例表现出来。然而，在越南的疟疾疟原虫和卵形疟原虫中获得了一些不稳定的结果。我们已经建立了一个改进的引物组，并显示了改进方法的有效性。

The emergence and spread of drug resistant malaria parasite Plasmodium falciparum has been a major obstacle to control and management of malaria. We have analyzed genetic polymorphism of pfcrt and pfmdr1 genes of P. falciparum, obtained from South-East Asis counties, Vietnam, Myanmar and Indonesia. There found specific characteristics in polymorphism of genotypes of the field isolates in each country. Many of the pfcrt genes from Vietnam samples exhibited a chloroquine sensitive genotype and the ratio of the sensitive type is more increasing in recent years. On the other hand, all of the pfcrt genes from Indonesia contained Thr76, which is essential for chloroquine resistant. Samples from these two countries are very interesting regarding to the effect of chloroquine; chloroquine is not used for treatment of P falciparum for several years in Vietnam and chloroquine is still the first choice of treatment in Indonesia. There are many types of pfcrt and pfmdr1 genes in Myanmar isolates, where patients are able to obtain several different drugs for treatment. The genotype analysis indicated that parasites have been essentially selected by drugs used in each region, and the polymorphic difference in parasites of each country might be the accumulated drug effects on parasites in each patient and the effects would be appeared as a ratio of genotypes.The identification protocols of four human malaria parasites by PCR have been established. However, some unstable results were obtained in P malarie and P ovale from Vietnam samples. We have set up a modified primer sets and shown the usefulness of the improved methods.