An intrinsic oscillator drives the blood stage cycle of the malaria parasite, Plasmodium falciparum

The blood-stage infection of the malaria parasite, Plasmodium falciparum, exhibits a 48-hour developmental cycle that culminates in the synchronous release of parasites from red blood cells, triggering 48-hour fever cycles in the host. This cycle could be driven extrinsically by host circadian processes, or by a parasite-intrinsic oscillator. To distinguish between hypotheses, we examined the P. falciparum cycle in an in vitro culture system that lacks extrinsic cues from the host and show that P. falciparum has molecular signatures associated with circadian and cell-cycle oscillators. Each of four strains examined has a unique period, indicating strain-intrinsic period control. Finally, we demonstrate that parasites have low cell-to-cell variance in cycle period, on par with a circadian oscillator. We conclude that an intrinsic oscillator is responsible for Plasmodium’s rhythmic life cycle. Time-series sampling of four strains of Plasmodium falciparum cultured in vitro. Cultures were sampled every three hours for up to 69 hours, allowing capture of at least one entire developmental cycle.