Role of p24δ in Regulating the Transition from Tachyzoite to Bradyzoite Development.

is an obligate intracellular parasite capable of infecting warm-blooded vertebrates, including humans. In its intermediate hosts, can transition between two life stages: the rapidly replicating tachyzoite and the quiescent bradyzoite. In , the p24 protein acts as a cargo receptor, cycling between the ER and Golgi in the early secretory pathway to recruit cargo proteins into nascent vesicles. However, the function of p24 in remains undefined. In this study, we identified four p24 proteins in , with Tgp24δ specifically localizing to the ER-Golgi system. Loss of p24δ in a type Ι strain (RH) significantly reduced proliferation and virulence in mice. Transcriptome and proteomic analyses showed that Tg tachyzoites expressed high levels of bradyzoite-specific genes, including , , and , under standard culture conditions. Additional data indicate that Tg tachyzoites can differentiate and form bradyzoites in vitro. This suggests that Tgp24δ is important for the parasite's growth.