Brefeldin A inhibits protein secretion and parasite maturation in the ring stage of Plasmodium falciparum.

The release of all newly synthesized soluble proteins from the ring stage of Plasmodium falciparum-infected erythrocytes was reversibly blocked by brefeldin A, indicating the presence of a conserved step of classical eukaryotic secretory export within the parasite. This implies that proteins exported to the erythrocyte cytosol undergo secretory release at the parasite plasma membrane and subsequent translocation across the vacuolar membrane. Along with inhibiting protein export brefeldin arrested parasite maturation, but the cells remained viable even after 24 h in the presence of the drug. The results suggest that secretory export may be important for development, but not for immediate survival, at the ring stage.