Tracking the Formation of Rhoptry Organelles and Parasitophorous Vacuole in Plasmodium falciparum Using the Green Fluorescent Protein

The most deadly Apicomplexan parasite is Plasmodium falciparum because it causes the globally spread human malaria especially in Africa. Like other members of Apicomplexa, Plasmodium is an intracellular parasite that uses an elaborate complex of apical secretory organelles (rhoptries, micronemes and dense granules) to invade its host cells and immediately accommodate itself in a parasitophorous vacuole (PV). In this study, we have cultured a previously established P. falciparum cell line that expresses the green fluorescent protein to visualize, in vivo, the formation of PV and rhoptry organelles. Parasites were tightly synchronized and investigated at short intervals and the formation of PV and rhoptry organelles were tracked in detail. Our results showed the development of circular extensions from PV in the asexual stages. Data showed that gametocytes develop very long tubular structures that run marginally underneath the erythrocyte cell membrane and reach the cell surface. Also, our data revealed the formation of crescent-like structures at the periphery of the immature schizonts, which were equivalent in number to and surrounding the nuclear lobes. These findings confirm the advantage of GFP use as a biomarker to track the formation of subcellular organelles and structures in vivo.