Episomal and stable expression of the luciferase reporter gene for quantifying Leishmania spp. infections in macrophages and in animal models

We have expressed the reporter firefly luciferase gene (LUC) in Leishmania donovani and Leishmania major either as part of episomal vectors or integra ted into the parasite genome under the control of their respective ribosoma l promoter regions. An excellent linear correlation between parasite number and luciferase activity was observed with all the transfectants. LUC-expre ssing recombinant parasites were useful to monitor Leishmania spp. infectio ns in macrophages or in animal models. For prolonged growth in absence of d rug selection, such as within animal models, quantitation of parasites is m ore reliable when the reporter gene LUC is stably integrated in the parasit e genome. These recombinant strains should be useful tools to monitor Leish mania growth under a number of conditions. (C) 2000 Elsevier Science B.V. A ll rights reserved.