2.5. Parasites

A drug screen was carried out with Trypanosoma cruzi clone Dm28c genetically modified to express luciferase (Dm28c-luc), kindly provided by Dr. Cristina Henriques [36]. The genetically modified T. cruzi clone Dm28c (Dm28c-Luc) has the firefly luciferase gene integrated into the genome, stably expressing the luminescent enzyme. The bioluminescent signal, proportional to the number of parasites, is produced by adding a D-luciferin substrate [37]. Trypomastigotes were harvested from supernatants of VERO cell cultures, infected at a ratio of 10:1 parasite/host cells, 4 days post-infection (4 dpi). Parasites were used for phenotypic drug screening procedures. Luminescent parasites are a reliable and sensitive tool that allows precise quantification of parasite load. The use of genetically modified organisms was approved under license CQB 105/99.