Reporter gene systems: A powerful tool for Leishmania studies

Abstract

Protozoan parasites of the genus Leishmania are responsible for leishmaniases, one of the most important anthropozoonotic diseases affecting millions of people worldwide. To date, there are no approved vaccines against leishmaniases for humans. At present, available treatment options lack specificity, which may lead to drug resistance and often cause adverse effects. Genomic analysis of Leishmania spp. revealed that most of the annotated genes encode hypothetical proteins, yet the functions of those proteins are still unknown. Characterization of these proteins is, hence, of utmost importance for the discovery of new therapeutic targets against leishmaniases. Reporter gene systems, or reporters, are powerful tools that enable the detection and measurement of targeted gene expression when introduced to a biological system. Over the years, numerous expression systems containing various reporters have been employed in characterizing several novel genes essential for parasite development. Such systems can be used to predict the subcellular localization of targeted proteins, screen antileishmanial drugs, and monitor the progression of infection within the vector and vertebrate hosts, among other uses. Therefore, it is critical to comprehend the available reporter gene expression systems to choose the most suitable for each study.

Keywords: Enzymatic reporter; Epitope tag; Fluorescent reporter; Gene expression; Neglected tropical diseases; Protein localization.

Graphical abstract

Fig. 1

Timeline of the application of reporters in Leishmania. Enzymatic systems (annotated in red) include chloramphenicol acetyltransferase (CAT), β-galactosidase (β-gal), luciferase (LUC), β-lactamase (β-lac), and haloalkane dehalogenase (Halo). Fluorescent systems (annotated in green) include green fluorescent protein (GFP), yellow fluorescent protein (YFP), Discosoma red fluorescent protein (DsRed), mCherry, infrared fluorescent protein (iRFP), and mNeonGreen (mNG). Epitope-based systems (annotated in purple) include hemagglutinin-tag (HA-tag), biotin-tag, and FLAG-tag.

Fig. 2

Schematic representation of enzymatic, fluorescent, and epitope-based reporter systems applied in Leishmania studies. Enzymatic reporters (red) involve enzyme-dependent reactions. Fluorescent reporters (green) exhibit fluorescence when exposed to light sources. Epitope-based reporters (purple) are composed of short amino acid sequences.