Dense granule proteins: key mediators of Toxoplasma gondii pathogenesis and therapeutic targets

Toxoplasma gondii (T. gondii) is an apicomplexan parasite that infects most warm-blooded animals, including approximately one-third of the human population worldwide. Dense granule proteins (GRAs), secreted from specialized organelles and trafficked to multiple compartments, including the parasitophorous vacuole (PV), parasitophorous vacuole membrane (PVM), host cytosol, and host cell nucleus following host cell invasion, have emerged as critical mediators of host-parasite interactions. This review provides a comprehensive analysis of our current knowledge of GRA proteins in toxoplasmosis pathogenesis and establishes a framework for developing novel interventions against this globally significant parasitic disease. Key GRA proteins form pore complexes that regulate PVM permeability, while GRA effectors manipulate host immunity to evade invasion. GRA proteins are essential for tissue cyst formation and bradyzoite differentiation, enabling lifelong chronic infection. The exceptional immunogenicity of GRA antigens has positioned them as promising candidates for diagnostic applications and vaccine development. Additionally, GRA proteins are attractive therapeutic targets through either the direct inhibition of effector-host protein interactions or by the disruption of effector export.