Plasmodium falciparum K13 Mutations Differentially Impact Ozonide Susceptibility and Parasite Fitness In Vitro.
Plasmodium falciparum K13 Mutations Differentially Impact Ozonide Susceptibility and Parasite Fitness In Vitro.
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DOI：
10.1128/mbio.00172-17
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发表时间：
2017-04-11
期刊：
影响因子：
6.4
通讯作者：
Fidock DA
中科院分区：
文献类型：
--
作者：
Straimer J;Gnädig NF;Stokes BH;Ehrenberger M;Crane AA;Fidock DA
恶性疟原虫对青蒿素衍生物（一线青蒿素联合疗法的基石）的耐药性在东南亚的出现和传播，突出表明迫切需要找到合适的替代药物。发现和开发工作已经确定了一系列具有吸引力的化学和药理特性的臭氧化物，这些臭氧化物被吹捧为合适的替代品。抗逆转录病毒疗法的部分耐药，定义为接受抗逆转录病毒疗法衍生物或抗青蒿素综合疗法治疗的疟疾患者中寄生虫清除延迟，与恶性疟原虫K13基因突变有关。根据显示ART衍生物和臭氧化物具有相似作用模式的报道，我们研究了表达突变体K13的寄生虫是否对臭氧化物OZ 439（artefenomel）和OZ 227（arterolane）具有交叉抗性。这项工作使用了一组来自柬埔寨的培养适应性临床分离株，这些分离株经过基因编辑以表达K13的变体形式。表型分析采用了环期存活试验（0至3 h的环期存活试验[RSA 0 - 3 h]），其结果早期已显示与患者的寄生虫清除率相关。我们的研究结果证明了OZ 277和双氢青蒿素（DHA）（ART的半合成衍生物）在携带K13突变C580 Y、R539 T和I543 T的寄生虫中的交叉耐药性。对于OZ 439，我们仅观察到携带罕见的K13 I543 T突变的寄生虫的交叉耐药性，没有证据表明流行的C580 Y突变提供了交叉耐药性。混合培养竞争实验与携带修改K13的同基因系显示变量的增长赤字取决于K13突变和寄生虫株，并提供了广泛传播的健身中性K13 C580 Y突变目前在东南亚流行的菌株的理由。近年来，ACT帮助将疟疾疾病负担减半;然而，对ART衍生物出现的耐药性可能会扭转这一重大进展。耐药性主要由恶性疟原虫K13基因突变驱动。这些突变对臭氧化物构成了威胁，臭氧化物被吹捧为具有类似作用模式的ART的有前途的替代品。我们报告说，DHA是相当有效的比OZ 439和OZ 277对ART敏感的无性血液阶段体外培养的寄生虫。我们还记录了突变体K13显著损害了注册药物OZ 277的活性。相比之下，OZ 439对大多数表达突变体K13的寄生虫系仍然有效，除了I543 T，其值得在基于田间的OZ 439功效研究中进一步监测。K13突变对寄生虫生长速率的影响差异很大，在菌株依赖性的背景下，最普遍的C580 Y突变在最近来自柬埔寨的培养适应菌株中是适应性中性的，柬埔寨是新兴ART耐药性的中心。
The emergence and spread in Southeast Asia of Plasmodium falciparum resistance to artemisinin (ART) derivatives, the cornerstone of first-line artemisinin-based combination therapies (ACTs), underscore the urgent need to identify suitable replacement drugs. Discovery and development efforts have identified a series of ozonides with attractive chemical and pharmacological properties that are being touted as suitable replacements. Partial resistance to ART, defined as delayed parasite clearance in malaria patients treated with an ART derivative or an ACT, has been associated with mutations in the P. falciparum K13 gene. In light of reports showing that ART derivatives and ozonides share similar modes of action, we have investigated whether parasites expressing mutant K13 are cross-resistant to the ozonides OZ439 (artefenomel) and OZ227 (arterolane). This work used a panel of culture-adapted clinical isolates from Cambodia that were genetically edited to express variant forms of K13. Phenotypic analyses employed ring-stage survival assays (ring-stage survival assay from 0 to 3 h [RSA0–3h]), whose results have earlier been shown to correlate with parasite clearance rates in patients. Our results document cross-resistance between OZ277 and dihydroartemisinin (DHA), a semisynthetic derivative of ART, in parasites carrying the K13 mutations C580Y, R539T, and I543T. For OZ439, we observed cross-resistance only for parasites that carried the rare K13 I543T mutation, with no evidence of cross-resistance afforded by the prevalent C580Y mutation. Mixed-culture competition experiments with isogenic lines carrying modified K13 revealed variable growth deficits depending on the K13 mutation and parasite strain and provide a rationale for the broad dissemination of the fitness-neutral K13 C580Y mutation throughout strains currently circulating in Southeast Asia. ACTs have helped halve the malaria disease burden in recent years; however, emerging resistance to ART derivatives threatens to reverse this substantial progress. Resistance is driven primarily by mutations in the P. falciparum K13 gene. These mutations pose a threat to ozonides, touted as promising alternatives to ARTs that share a similar mode of action. We report that DHA was considerably more potent than OZ439 and OZ277 against ART-sensitive asexual blood-stage parasites cultured in vitro. We also document that mutant K13 significantly compromised the activity of the registered drug OZ277. In contrast, OZ439 remained effective against most parasite lines expressing mutant K13, with the exception of I543T that merits further monitoring in field-based OZ439 efficacy studies. K13 mutations differed considerably in their impact on parasite growth rates, in a strain-dependent context, with the most prevalent C580Y mutation being fitness neutral in recently culture-adapted strains from Cambodia, the epicenter of emerging ART resistance.