Real-time PCR to quantify Leishmania donovani in hamsters

Visceral leishmaniasis, a vector-borne disease caused by Leishmania donovani and Leishmania infantum, currently affects 12 million individuals in 88 countries. In the present study, a real-time PCR (rt-PCR) assay has been optimized and validated against 2 other routine methods, i.e., microscopy and limiting dilution culture assay, to estimate parasite load in the liver of infected Syrian hamsters (Mesocricetus auratus). A set of specific primers amplified a 116-bp target template of the kinetoplastid DNA of L. donovani in a SYBR® Green-based rt-PCR assay. To assess the methods, we tested 2 anti-leishmanial compounds belonging to the class of arylimidamides, DB745 (2,5-bis[2-ethoxy-4-(2-pyridylimino)aminophenyl]furan) and DB766 (2,5-bis[2-(2-propoxy)-4-(2-pyridylimino)aminophenyl]furan) for efficacy in vivo in Syrian hamsters infected with L. donovani promastigotes. Parasite load was quantified in liver by all 3 methods and was found comparable. Of the 3 methods, rt-PCR was the fastest and most convenient, sensitive, and reproducible method.