Transfection of Leishmania tropica with Green Fluorescent Protein (gfp) Gene and Investigation of the In Vitro Drug Effect

Cutaneous leishmaniasis (CL) is a parasitic disease transmitted by vector sand flies Phlebotomus and Lutzomyia. This disease is characterized by long time non-healing skin lesions, and caused by Leishmania species. CL is the most common infection in Eastern and Southeastern Anatolia in Turkey and L. tropica is known as the main agent of the disease. Number of cases is increasing in our country in time because of malnutrition, migration, travel, low socioeconomic level and ecological changes. For the treatment, the pentavalent antimonials are often used as intralesionally for many years, and it was reported that resistant cases have increased in recent years. New treatment methods and anti-Leishmanial activity of new agents have been investigated because of side effects, resistance development and toxic reactions of the present drugs. These studies are first carried out in vitro and afterwards with in vivo experimental animal models. Reporter gene technology has been used to investigate a variety of purposes like biological events in microorganisms and the efficacy and resistance of drugs in recent years. The major areas that green fluorescent protein (gfp) used are that they can be incorporated into different genes to determine the amount of expression of these genes in different organisms and can be used as markers in living cells. Especially gfp gene, which encodes the green fluorescent protein, is widely used nowadays. Gene-based assays have several advantages like being easy to follow-up, inexpensive and have improved biosecurity. The aim of the present study was to perform the transfection of L. tropica with "enhanced gfp (egfp)" and in vitro usefulness of gfp-transfectants as a drug screening model in comparison to the conventional methods. Promastigotes of L. tropica were transfected with p6.5/egfp by electroporation and selected for tunicamycin-resistance as previously described. L. tropica promastigotes transfected with gfp and in vitro effect of meglumine animoniate was assessed using different methods such as fluorescence microscopy, fluorometer and XTT (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxyanilide) assay. The use of gfp-transfected Leishmania strains was found more rapid and more sensitive by fluorescent microscopy and fluorometry than conventional assays for the evaluation of potential anti-leishmanial agents. Consequently, stable gfp-transfected Leishmania species will be used in vitro and in vivo for screening of anti-leishmanial drugs and vaccine development as well as for understanding the biology of the host-parasite interactions at the cellular level. As a result ot this study, gfp transfected model using a Turkish L. tropica isolate was established to be used in further studies.