Gene Expression Modification Initiates Stage Conversion in Toxoplasma gondii

Toxoplasma gondii is an obligate, intracellular parasite with worldwide distribution and causes toxoplasmosis in humans. The T. gondii life cycle includes the conversion from tachyzoite to bradyzoite – stages which give rise to acute and chronic infection, respectively. It is hypothesized that modification of gene expression is the mechanism which activates this conversion process. Microarray analysis highlighted a cluster of genes activated early during the conversion process, and a shared consensus sequence thought to be a gene expression modifier binding site was identified computationally. Using a reporter gene approach, the ability of this binding site to cause chronic stage gene expression was examined. The results of this study demonstrate the control an early chronic stage promoter element has on stage conversion and provides insight for future studies on chronic stage gene regulation