title: Molecular mechanisms of drug resistance in natural Leishmania populations vary with genetic background.
abstract: 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.
authors.affiliation: Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.
authors.forename: Saskia
authors.initials: S
authors.lastname: Decuypere
authors.forename: Manu
authors.initials: M
authors.lastname: Vanaerschot
authors.forename: Kirstyn
authors.initials: K
authors.lastname: Brunker
authors.forename: Hideo
authors.initials: H
authors.lastname: Imamura
authors.forename: Sylke
authors.initials: S
authors.lastname: Müller
authors.forename: Basudha
authors.initials: B
authors.lastname: Khanal
authors.forename: Suman
authors.initials: S
authors.lastname: Rijal
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Dujardin
authors.forename: Graham H
authors.initials: GH
authors.lastname: Coombs
mesh_terms: D000818:Animals; D000965:Antimony / Q000494:pharmacology*; D000981:Antiprotozoal Agents / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D016054:DNA, Protozoan / Q000235:genetics; D004351:Drug Resistance; D020869:Gene Expression Profiling; D014644:Genetic Variation; D006801:Humans; D007893:Leishmania donovani / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D007898:Leishmaniasis, Visceral / Q000469:parasitology*; D009390:Nepal; D015800:Protozoan Proteins / Q000096:biosynthesis
chemical_list: D000981:Antiprotozoal Agents; D016054:DNA, Protozoan; D015800:Protozoan Proteins; D000965:Antimony