Toxoplasma secretory proteins and their roles in parasite cell cycle and infection

Abstract The Apicomplexa are named for their unique apical secretory organelles: the micronemes, the rhoptries, and the dense granules (DGs). The contents of these organelles are critical for the successful invasion and intracellular survival of Toxoplasma gondii. Microneme proteins are secreted in a calcium-dependent manner and are critical for adhesion and bridging with the host, as well as parasite egress from host cells. Rhoptry neck molecules, with microneme proteins, form the moving junction that enables the parasite to enter the host, while other rhoptry proteins are important for modulation of host cell signaling and formation of the parasitophorous vacuole. DG proteins play important roles in the interaction with the host as well as survival within the host. This chapter provides a detailed overview of the functions of Toxoplasma secretory proteins and their roles in invasion, egress, and host cell parasitism.