Differential gene expression studies to explore the molecular mechanism of drug resistance in Leishmania donovani field isolates

Abstract

Visceral leishmaniasis or kala-azar is a major cause of morbidity and mortality in Indian subcontinent caused by an obligatory intracellular protozoan parasite Leishmania donovani. Since there is no vaccine available for prophylaxis, the control of the disease relies solely on chemotherapy which includes one and only first line drug, sodium antimony gluconate (SAG). Unfortunately, since last decade treatment has been eroded by development of resistance in parasite against this drug and has becomes a major obstacle in the treatment especially in India. As there is no effective, safe and economical drug available so far, prevention and circumvention of resistance towards antimonials has become WHO priority. Studies on laboratory generated mutants of arsenite/antimony resistant mutants have generated wealth of information suggesting that resistance is an interplay between uptake, efflux and sequestration of active drug molecule. Very few studies have been done so far on clinical resistance. These studies suggested that mechanism of natural antimony resistance is multifactorial and may be differfrom laboratory resistance. As whole genome sequence of the parasite is available, differential gene expression study has good potential to study multiplicity of the antimony clinical resistance mechanism. Therefore, present study aimed to explore the molecular mechanism of SAG resistance in field isolates of L. donovani by differential gene expression analysis. Cloning, sequencing and overexpression of identified differentially expressed gene will illucidate its role in antimony resistance, if any. The study has also been aimed to develop luciferase reporter gene assay for monitoring resistance phenotype in field isolates and large scale screening of antileishmanials in high throughput screening.