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Session 3, Abstract 15

PREPARING AND RELEASING ANTIGEN FROM THE VACUOLE OF TOXOPLASMA GONDII

Anh L. Diep*1 , Angel K. Kongsomboonvech*1 and Michael L. Reese2 (Kirk D.C. Jensen1 ), School of Natural Sciences, University of California, Merced1 ; University of Texas, Southwestern2 *Equal contribution

Toxoplasma gondii is an obligate intracellular parasite and thus has evolved virulence factors to avoid immunity-related detection and clearance. Upon invasion, T. gondii steals the host cell’s membrane to form a parasitic vacuole (PV.) From studying differences in T. gondii strain virulence, it is known that antigen presentation is necessary to elicit immunity-related GTPases which lyse the parasitic vacuole to clear the parasite and release T. gondii antigen into the cytosol to enter the MHC Class I pathway. Past research has shown that key virulence factors of interest are rhoptry-secreted proteins, particularly ROP5 and ROP18, which inhibit IRGs from interacting with and lysing the PV. Moreso, it would appear that ROP5 and ROP18 interact with IRGa6 and IRGb6 which have been shown to localize upon the PV. Interestingly, there appears to be a mysterious unknown IRG that is not inhibited by ROP5 and ROP18 and can still induce antigen presentation. There is also a T. gondii protease, ASP5, of interest that is believed to be involved in the antigen presentation pathway. Current research is aimed at identifying the mystery IRG and confirming the protease’s involvement in the antigen presentation pathway.