By Ashley Smith, Beliyu Habtemariam, Caitlin Harris, Paul James Solis

Faculty Mentor: Professor Swati Agrawal

Abstract

Toxoplasma gondii is an obligate intracellular protozoan parasite that can cause fatal infection in immunocompromised individuals, stillbirth and miscarriage in pregnant women, and congenital birth defects in infants. According to the CDC, around 800,000 individuals are infected by T. gondii in the United States every year. Recently, two novel calcium ion regulator proteins, TGGT1_253640 and TGGT1_222060, were characterized by the Agrawal 2023 Research group. Conditional knockdowns were used to study the role of these genes in calcium signaling. These proteins are normally expected to be involved in motility, egress, and invasion, processes of which are important for replication and survival of the parasite. Cats are definitive hosts for T. gondii, but the parasite can thrive in any mammalian host. Humans commonly acquire oocysts (the dormant stage) through the consumption of undercooked meat and contact with contaminated cat feces. Activated oocysts can lead to acute infections in humans where the parasites thrive at the average body temperature of 37 °C and the average pH of 7 in retinal, brain, and blood cells. This research aimed to investigate the impact of temperature and pH stress on both wild-type parasites and calcium ion transporter mutants. We employed plaque assays and replication assays to evaluate the fitness and replication capacity of these parasites under different stress conditions. These experiments will help us evaluate the role of calcium ion transporters in the T. gondii lytic cycle.