Whole genome sequence analysis of drug sensitive and resistant Leishmania isolates originated from patients of kala-azar.

Visceral leishmaniasis (VL) or kala-azar, caused by Leishmania donovani is the most severe form of leishmaniasis, being fatal if left untreated. Emergence of drug resistant Leishmania parasites has repeatedly truncated the lifespan of currently available drugs. A field isolate of L. donovani (K133WT) derived from bone marrow aspirates of VL patient, propagated in medium M199 was made resistant to artesunate, paromomycin and miltefosine in vitro by stepwise exposure to increasing drug concentration. The artesunate resistant parasite designated as K133AS-R exhibited >3 fold increase in the mean IC50 (50% inhibitory concentration) compared to wild type K133WT. The paromomycin resistant parasite designated as K133PMM-R exhibited >6 fold increase in the mean IC50 (50% inhibitory concentration) compared to wild type K133WT. The miltefosine resistant parasite designated as K133M30 exhibited >30 fold increase in the mean IC50 (50% inhibitory concentration) compared to wild type K133WT. To decipher the resistance mechanism, genome of four K133WT, K133PMM-R, K133AS-R and K133M30 L. donovani isolates were sequenced using second generation (Illumina) sequencing technology. This genomic study will illuminate possible mechanisms of resistance against the two drugs (artemisinin paromomycin and miltefosine).