Genomic analysis of resistance to antimony and amphotericin B in Leishmania infantum

Antimony-derived compounds remain the first-line treatment against leishmaniasis despite increasing drug resistance, whereas clinical resistance no yet threatens amphotericin B (AmB), the second-line treatment. Quantitative proteomics using stable isotope labelling of amino acids in cell culture (SILAC) and whole genome sequencing using Illumina technology were used in order to better characterize in vitro generated Leishmania infantum antimony (Sb2000.1) and amphotericin B (AmB1000.1) resistant mutants. Many new interesting proteins were found to be differentially regulated in the different mutants. However, the ABC transporter MRPA, a key player in antimony resistance, was the only protein who give raise to a resistance phenotype when overexpressed in the wild-type (WT) cells suggesting that other identified proteins might play an indirect role in resistance phenotype. At the DNA level, aneuploidy was observed for 7 chromosomes in Sb2000.1 and 5 chromosomes in AmB1000.1. Furthermore, amplicon derived from chromosome 23 and 17 were observed in Sb2000.1, whereas no amplicon were detected in AmB1000.1. This result could explain the stability of the resistance phenotype in the AmB mutant. Overall, our results suggest that differentially expressed proteins and variation in chromosome copy numbers are important features of trivalent antimony (SbIII) and AmB resistant Leishmania mutants.