Universidad Nacional de Rosario (UNR) 1 article published in JoVE Biochemistry In Vitro Drug Screening Against All Life Cycle Stages of Trypanosoma cruzi Using Parasites Expressing β-galactosidase Victoria Lucia Alonso1,2, Romina Manarin1, Virginia Perdomo1, Ernesto Gulin3, Esteban Serra1,2, Pamela Cribb1,2 1Área Parasitología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, 3Instituto de Investigaciones Biomédicas (INBIOMED), Universidad de Buenos Aires (UBA) Facultad de Medicina, CONICET We describe a high-throughput colorimetric assay measuring β-galactosidase activity in three life cycle stages of Trypanosoma cruzi, the causative agent of Chagas disease. This assay can be used to identify trypanocidal compounds in an easy, fast, and reproducible manner.