Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.
PLoS Negl Trop Dis. 2012;6(2):e1514. doi: 10.1371/journal.pntd.0001514. Epub 2012 Feb 28.
The evolution of drug-resistance in pathogens is a major global health threat. Elucidating the molecular basis of pathogen drug-resistance has been the focus of many studies but rarely is it known whether a drug-resistance mechanism identified is universal for the studied pathogen; it has seldom been clarified whether drug-resistance mechanisms vary with the pathogen's genotype. Nevertheless this is of critical importance in gaining an understanding of the complexity of this global threat and in underpinning epidemiological surveillance of pathogen drug resistance in the field. This study aimed to assess the molecular and phenotypic heterogeneity that emerges in natural parasite populations under drug treatment pressure. We studied lines of the protozoan parasite Leishmania (L.) donovani with differential susceptibility to antimonial drugs; the lines being derived from clinical isolates belonging to two distinct genetic populations that circulate in the leishmaniasis endemic region of Nepal. Parasite pathways known to be affected by antimonial drugs were characterised on five experimental levels in the lines of the two populations. Characterisation of DNA sequence, gene expression, protein expression and thiol levels revealed a number of molecular features that mark antimonial-resistant parasites in only one of the two populations studied. A final series of in vitro stress phenotyping experiments confirmed this heterogeneity amongst drug-resistant parasites from the two populations. These data provide evidence that the molecular changes associated with antimonial-resistance in natural Leishmania populations depend on the genetic background of the Leishmania population, which has resulted in a divergent set of resistance markers in the Leishmania populations. This heterogeneity of parasite adaptations provides severe challenges for the control of drug resistance in the field and the design of molecular surveillance tools for widespread applicability.
病原体耐药性的进化是一个主要的全球健康威胁。阐明病原体耐药性的分子基础一直是许多研究的重点，但很少有人知道所确定的耐药机制是否普遍适用于研究的病原体；也很少有人澄清耐药机制是否随病原体的基因型而变化。然而，这对于了解这一全球威胁的复杂性以及为现场病原体耐药性的流行病学监测提供基础至关重要。本研究旨在评估在药物治疗压力下自然寄生虫群体中出现的分子和表型异质性。我们研究了对锑剂药物具有不同敏感性的原生动物寄生虫利什曼原虫（L.） Donovan 的品系；这些品系源自属于在尼泊尔利什曼病流行地区循环的两个不同遗传群体的临床分离株。在所研究的两个群体的品系中，对受锑剂药物影响的寄生虫途径进行了五个实验水平的特征描述。对 DNA 序列、基因表达、蛋白质表达和巯基水平的特征描述揭示了一些分子特征，这些特征仅在研究的两个群体中的一个群体中标记了耐锑寄生虫。最后一系列体外应激表型实验证实了这两个群体的耐药寄生虫之间存在这种异质性。这些数据提供了证据表明，天然利什曼种群中与锑剂耐药相关的分子变化取决于利什曼种群的遗传背景，这导致了利什曼种群中耐药标记的差异。寄生虫适应性的这种异质性为现场耐药性控制和广泛适用性的分子监测工具的设计带来了严峻挑战。
