Happi T C, Thomas S M, Gbotosho G O, Falade C O, Akinboye D O, Gerena L, Hudson T, Sowunmi A, Kyle D E, Milhous W, Wirth D F, Oduola A M J
Malaria Research Laboratories, Postgraduate Institute for Medical Research and Training, College of Medicine, University of Ibadan, Ibadan, Nigeria.
Ann Trop Med Parasitol. 2003 Jul;97(5):439-51. doi: 10.1179/000349803235002489.
Chloroquine (CQ) resistance in Plasmodium falciparum has been associated with specific point mutations in the pfcrt and pfmdr-1 genes. In the present study, 30 children aged 1-12 years, who were all suffering from acute, uncomplicated, P. falciparum malaria in Ibadan, Nigeria, were evaluated to assess the association between these mutations and clinical outcome following treatment with CQ. The parasites, in blood samples collected pre-treatment and, in those who failed treatment, on the day symptoms re-occurred post-treatment, were genotyped using the polymorphic MSP1, MSP2 and GLURP loci and PCR-RFLP. The results showed that, pre-treatment, all 30 patients had polyclonal infections, the mean numbers of P. falciparum clones detected per infection being 2.6 with MSP1, 4.2 with MSP2 and 2.8 with GLURP. The T76 allele of pfcrt and the Y86 allele of pfmdr-1 were found in 53% and 40%, respectively, of the pre-treatment samples from the 15 patients who failed CQ treatment, but the Y1246 mutation in pfmdr-1 was never detected. Although the parasites from the two patients with high-grade (RIII) resistance to CQ had both of these point mutations, the presence of the T76 allele of pfcrt or the Y86 allele of pfmdr-1 (considered individually) could not be used to predict treatment outcome. However, a high frequency of clonal multiplicity may confound attempts to associate the point mutations in pfcrt or pfmdr-1 with clinical response to CQ. It remains unclear whether the present results represent the characteristics of the predominant parasite populations in the study area. Further studies are needed before the strength of the association between the point mutations identified as markers of drug resistance and clinical outcome can be accurately evaluated, in this and other regions of intense transmission.
恶性疟原虫对氯喹（CQ）的耐药性与pfcrt和pfmdr - 1基因中的特定点突变有关。在本研究中，对尼日利亚伊巴丹的30名1至12岁儿童进行了评估，这些儿童均患有急性、非复杂性恶性疟原虫疟疾，以评估这些突变与CQ治疗后临床结果之间的关联。使用多态性MSP1、MSP2和GLURP基因座以及PCR - RFLP对治疗前采集的血样中的寄生虫进行基因分型，对于治疗失败的患者，则在治疗后症状复发当天进行基因分型。结果显示，治疗前，所有30例患者均为多克隆感染，每次感染检测到的恶性疟原虫克隆平均数，使用MSP1为2.6个，使用MSP2为4.2个，使用GLURP为2.8个。在CQ治疗失败的15例患者的治疗前样本中，分别有53%和40%检测到pfcrt的T76等位基因和pfmdr - 1的Y86等位基因，但从未检测到pfmdr - 1中的Y1246突变。尽管对CQ具有高度（RIII）耐药性的两名患者的寄生虫都有这两种点突变，但pfcrt的T76等位基因或pfmdr - 1的Y86等位基因（单独考虑）的存在不能用于预测治疗结果。然而，高频率的克隆多样性可能会混淆将pfcrt或pfmdr - 1中的点突变与对CQ的临床反应相关联的尝试。目前尚不清楚本研究结果是否代表了研究区域内主要寄生虫种群的特征。在准确评估被确定为耐药性标志物的点突变与临床结果之间关联的强度之前，还需要在本地区以及其他高传播地区进行进一步研究。
