By Abigail Glenn, Exotica Hall, Elizabeth Sullivan

Faculty Mentor: Swati Agrawal

Abstract

apicomplexan Toxoplasma gondii. In immunocompromised individuals, such as those with preexisting illness, toxoplasmosis can be deadly. As an intracellular parasite, T. gondii has mechanisms for motility, invasion, replication, and egress, during which calcium is a key regulator. To signal invasion, the cytosolic concentrations of calcium increases. This said, extreme dysregulation of extracellular, intracellular, and endoplasmic reticulum (ER) calcium concentrations can also cause parasite death. TGGT1_253640 is a novel gene recently shown to localize to the parasite ER, which encodes a calcium ion transporter transmembrane protein (Agrawal et al unpublished). Previously, an auxin system was used to create a conditional knock down line of T. gondii for this gene so as to clarify the function of this protein. Previous studies have shown that caffeine is an agonist of calcium release from the ER leading to activation of invasion and egress but not motility of the parasites.
For our project, we hypothesized that caffeine would increase cytosolic calcium and signal increased invasion in wild type parasites, whereas the mutant parasites would show further dysregulation of calcium concentrations, leading to parasite death. We aim to elucidate the role of TGGT1_253640 through plaque assays which represent parasite viability through successful lysis of host cells and replication assays which represent parasite viability through successful invasion and fission. Results indicate that addition of caffeine trends toward a decrease of replication in mutant T. gondii. However, plaque assays indicate caffeine increases lysis in mutant lines, though, more replicants are needed to clarify plaque assay results.