对尼日利亚恶性疟原虫分离株中 pfhrp2 和 pfhrp3 基因缺失的分子监测及其对快速诊断检测的影响。
Molecular surveillance of pfhrp2 and pfhrp3 genes deletion in Plasmodium falciparum isolates and the implications for rapid diagnostic tests in Nigeria.
机构信息
Department of Pharmacology and Therapeutics, University of Ibadan, Ibadan, Nigeria; Department of Pharmacy Technician Studies, Bayelsa State College of Health Technology, Nigeria.
Institute of Tropical Medicine, University of Tübingen, Germany.
出版信息
Acta Trop. 2019 Aug;196:121-125. doi: 10.1016/j.actatropica.2019.05.016. Epub 2019 May 16.
Prompt diagnosis and appropriate treatment of malaria remain the hallmark for reducing malaria-related mortality in high transmission areas. Plasmodium falciparum histidine-rich protein2 (PfHRP2) based rapid diagnostic tests (RDT) play a vital role in prompt and accurate malaria diagnosis. However, pfhrp2 gene deletion threatens the RDT test sensitivity. This study reports the presence of pfhrp2 and pfhrp3 genes deletion among parasite isolates in Nigeria. Febrile children were screened using histidine-rich protein (HRP2) specific RDT (SD-Bioline RDT) and microscopy for P. falciparum infections. All RDT negative samples were re-evaluated by polymerase chain reaction (PCR). The presence of parasite in RDT false negative cases and randomly selected RDT positive cases were validated using PCRs targeting glutamate-rich protein (glurp) and merozoite surface proteins (msp-1 and msp-2). Thereafter, exon 2 of pfhrp2 and pfhrp3 were amplified, and Sanger sequenced. A total of 511 febrile children were enrolled out of which 309 (61%) were positive by RDT. The presence of pfhrp2 and pfhrp3 genes were analyzed in 66 PCR positive samples comprising of 31 RDT false negative and 35 RDT true positive randomly selected samples. The pfhrp2 and pfhrp3 genes failed to amplify in 17% (11/66) and 6% (4/66) samples, respectively. Seven of the eleven samples had only pfhrp2 deletion while four had both pfhrp2 and pfhrp3 deletions. The absence of the pfhrp2 gene may be responsible for the seven RDT false negative cases observed. Three RDT positive cases lacked pfhrp2 whereas pfhrp3 was absent in only four RDT false negative cases. The pfhrp2 and pfhrp3 amino acid repeat sequences were highly diverse. The P. falciparum isolates lacking pfhrp2 and pfhrp3 genes may be circulating and contributing to RDT false negativity in Nigeria. More studies in larger population and seasonally defined cases will be needed to determine the extent of pfhrp2/3 genes deletion in different geographical areas of Nigeria.
及时诊断和适当治疗疟疾仍然是降低高传播地区疟疾相关死亡率的关键。恶性疟原虫高变区蛋白 2(PfHRP2)基于快速诊断检测(RDT)在快速准确的疟疾诊断中起着至关重要的作用。然而,pfhrp2 基因缺失威胁着 RDT 检测的敏感性。本研究报告了尼日利亚寄生虫分离株中 pfhrp2 和 pfhrp3 基因缺失的存在。发热儿童采用富组氨酸蛋白(HRP2)特异性 RDT(SD-Bioline RDT)和显微镜检查疟原虫感染。所有 RDT 阴性样本均采用聚合酶链反应(PCR)重新评估。在 RDT 假阴性病例和随机选择的 RDT 阳性病例中,采用针对谷氨酸丰富蛋白(glurp)和裂殖体表面蛋白(msp-1 和 msp-2)的 PCR 进行验证。此后,扩增 pfhrp2 和 pfhrp3 的外显子 2,并进行 Sanger 测序。共纳入 511 例发热儿童,其中 309 例(61%)通过 RDT 检测为阳性。在 66 例 PCR 阳性样本中分析了 pfhrp2 和 pfhrp3 基因的存在,其中包括 31 例 RDT 假阴性和 35 例随机选择的 RDT 真阳性样本。在 17%(11/66)和 6%(4/66)的样本中,pfhrp2 和 pfhrp3 基因未能扩增。11 个样本中有 7 个只有 pfhrp2 缺失,4 个既有 pfhrp2 又有 pfhrp3 缺失。pfhrp2 基因的缺失可能是观察到的 7 例 RDT 假阴性病例的原因。3 例 RDT 阳性病例缺乏 pfhrp2,而 4 例 RDT 假阴性病例中仅缺乏 pfhrp3。pfhrp2 和 pfhrp3 氨基酸重复序列高度多样化。缺乏 pfhrp2 和 pfhrp3 基因的恶性疟原虫分离株可能在循环,并导致尼日利亚 RDT 假阴性。需要在更大的人群中和季节性定义的病例中进行更多的研究,以确定尼日利亚不同地理区域 pfhrp2/3 基因缺失的程度。