Hammondia hammondiis the nearest relative ofToxoplasma gondii, but unlikeT. gondiiis obligately heteroxenous. We have comparedH. hammondiandT. gondiidevelopmentin vitroand identified multipleH. hammondi-specific growth states. Despite replicating slower thanT. gondii,H. hammondiwas resistant to pH-induced tissue cyst formation early after excystation. However, in the absence of stressH. hammondispontaneously converted to a terminally differentiated tissue cyst stage whileT. gondiidid not.

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... edH. hammondicould infect new host cells for up to 8 days following excystation, and this period was exploited to generate stably transgenicH. hammondi. Coupled with RNAseq analyses, our data clearly show thatH. hammondizoites grow as stringently regulated life stages that are fundamentally distinct fromT. gondiitachyzoites and bradyzoites.