中缅边境地区恶性疟原虫K13基因的多态性分析

Polymorphisms of the K13 gene of Plasmodium falciparum in the China-Myanmar border area

目的通过检测中缅边境地区恶性疟原虫Kelch 13螺旋体蛋白基因(Kelch 13-propeller, K13)突变的动态变化情况,为当地恶性疟治疗策略的制定提供科学依据。方法收集以往中缅边境地区中国云南省西双版纳州景洪市、缅甸克钦邦拉咱市和佤邦第二特区勐冒县恶性疟病例滤纸血标本175份,采用巢式PCR法扩增K13基因第426~676位点片段,对扩增产物测序并进行统计分析。结果 2001年西双版纳州景洪市30份滤纸血中仅1份检出恶性疟原虫K13基因F446I突变;2006年标本未检测到突变。缅甸拉咱市恶性疟原虫K13基因共检测到5种突变(F446I、C469Y、Y511H、E556D和P574L),其中以F446I突变为主,突变率由2001年的45%(9/20)降低至2012年的25%(10/40);勐冒县2009年标本中未检测到K13基因突变。结论中缅边境地区缅甸拉咱市恶性疟原虫K13基因存在较多类型的突变,以F446I突变为主,提示该地区恶性疟原虫可能存在青蒿素抗性,建议加强对中缅边境地区恶性疟原虫药物抗性监测。

Objective To analyze dynamic changes in the Kelch 13-propeller(K13) gene of Plasmodium falciparum in the China-Myanmar border area in order to provide scientific evidence for the formulation of effective local treatment strategies. Methods One hundred and seventy-five blood samples of P. falciparum on filter paper were collected from Xishuangbanna Prefecture, Yunnan Province, China and the City of Lazan, Kachin State and Mengmao County, the Second Special Zone of Shan State in Myanmar. Fragments from positions 426 to 676 of the K13 gene were amplified using nested PCR, and the products were sequenced and statistically analyzed. Results Only one sample of P. falciparum(1/30) with the K13 F446 I mutation was detected in the City of Jinghong, Xishuangbanna Prefecture in 2001, and no mutations were detected in 25 samples in 2006. Five mutations(F446 I, C469 Y, Y511 H, E556 D, and P574 L) of the K13 gene were detected, with the dominant mutation being F446 I in the City of Lazan, Myanmar. The rate of mutation decreased from 45%(9/20) in 2001 to 40%(8/20) in 2007 and 25%(10/40) in 2012. No mutations in the K13 gene were detected in 40 samples from Mengmao County, Myanmar in 2009. Conclusion Numerous mutations in the K13 gene were found in the City of Lazan, Myanmar, with the dominant mutation being F446 I. These findings suggest that P. falciparum in this area is probably resistant to artemisinin. Accordingly, monitoring of P. falciparum resistance should be enhanced in the China-Myanmar border area.