Assays for the optimization of drug discovery in visceral leishmaniasis

Visceral Leishmaniasis (VL) encompasses a broad range of manifestations of protozoan parasite Leishmania in human. This infection remains asymptomatic/subclinical in many cases, or can follow an acute, subacute, or chronic course. It adversely affects productivity and welfare. Available treatment options are not satisfactory, and humans are still losing the battle with VL. Therefore, development of a potent drug against VL is urgently required but it is a challenging task because the parasites are well protected within the host cells. Persisting epidemics and evolution of drug-resistant strains impose continuous search for new antileishmanial and it becomes a critical priority on the global VL research agenda. Before pre-clinical study and clinical trials millions of compounds are screened to discover a potent drug. In vitro drug screening is an essential part of antileishmanial drug development. Performing in vitro screening with a huge number of molecules is not an easy task because there are various assay methods and they are subjected to numerous sources of variability in different laboratories across the globe. Therefore, this review provides an overview of various biochemical and cell-based assays for evaluating the activity of antileishmanial molecules during in vitro and in vivo drug screening.