Differential RNA expression profile in antimony resistant and antimony sensitive clinical isolates of Leishmania donovani

Infection with antimony resistant (SbR) but not with sentitive (SbS) Leishmania donovani (LD) gives rise to aggressive pathology and higher organ parasite load in infected patients, the cause of which is far from clear. The pentose phosphate pathway (PPP) is a key route of glucose metabolism in most organisms, providing NADPH for use as a cellular reductant and various carbohydrate intermediates used in cellular metabolism. Alteration in PPP is primary reason behind aggressive pathology and multi drug resistance in several types of carcinoma and other infectious disease model. A time kinetic study with equal inoculum of SbRLD and SbSLD promastigotes and host cells infected with equal number of SbR and SbSLD, resulted in remarkable higher growth rate in SbRLD which is also reflected in terms of their DNA content. Our result showed an activated PPP pathway in response to oxidative stress in SbRLD. Our result suggest that SbRLD have adapted to a higher nucleotide metaboism that provide them a selective survival advantage in presence of drug mediated oxidative stress and explains, in part, the cause of higher organ parasite load in SbRLD infected patients. Three clinical isolates representing SbRLD (BHU575, BHU814 and BHU138) and three clinical isolates representing SbSLD (BHU77, BHU581 and BPK206) along with sensitive reference strain Ag83 were grown in 75cm2 tissue culture flask. Total RNA was isolated from each isolate and two biological replicates were prepared and submitted for microarray profiling. The main objective of the microarray analysis was to compare differential RNA expression profile between antimony resistant and antimony sensitive Leishmania donovani isolates with particular focus to identify those RNAs which are involved in carbohydrate metabolism