Chronic Toxoplasma gondii infections are widespread and their reactivation can cause life-threatening disease in immunocompromised individuals and recurrent ocular lesions in the immunocompetent. The recently identified master regulator of chronic differentiation, BFD1, provides an unprecedented opportunity to investigate the molecular events that establish and maintain chronic T. gondii infections. BFD1 is necessary for chronic differentiation in cell culture and in mouse models of infection, and its expression is sufficient to induce chronic differentiation. Consistent with a sustained requirement for BFD1 during chronic stage maintenance, the differentiation program is reversed upon conditional down-regulation of BFD1. Preliminary results indicate that BFD1 is post-transcriptionally controlled through its 5? UTR, leading to the hypothesis that translational regulation of BFD1 is fundamental to the development and maintenance of chronic T. gondii stages. This proposal seeks to integrate BFD1 into a broader regulatory network through three complementary aims.
Aim 1 will examine the sequence elements, secondary RNA structures, and ribosomal occupancy dynamics that mediate BFD1 translational regulation.
Aim 2 will use conditional depletion of BFD1 to characterize transcriptional and proteomic changes that mediate reactivation, and the molecular circuits that maintain the differentiated state. Finally, Aim 3 will extend the regulatory pathways that control differentiation by screening for genes involved in the translational regulation of BFD1 and further examining the function of transcription factors directly regulated by BFD1. The overarching goal of this comprehensive analysis is to understand the conditions that promote chronic differentiation and license the development of curative therapies against toxoplasmosis.
Toxoplasma gondii is a parasite and NIAID category B Biodefense agent that chronically infects about a quarter of the world's population, causing recurrent ocular lesions in about 2% of cases and life-threatening infections in immunocompromised individuals. The proposed study will characterize the mechanisms that allow parasites to enter a chronic state that is resistant to all current therapies and acts as a reservoir for reactivation. Our work will lay the molecular foundation for future therapies that can prevent and eliminate chronic Toxoplasma infections.
