The artemisinin-induced dormant stages of Plasmodium falciparum exhibit hallmarks of cellular senescence and drug resilience.

Abstract

Recrudescent infections with human malaria parasite, Plasmodium falciparum, presented traditionally the major setback of artemisinin-based monotherapies. Although introduction of artemisinin combination therapies (ACT) largely solved the problem, the ability of artemisinin to induce dormant parasites still poses major obstacle for current as well as future malaria chemotherapeutics. Here, we developed a robust laboratory model for induction of dormant P. falciparum parasites and characterized their transcriptome, drug sensitivity profile and cellular ultrastructure. We show that P. falciparum dormancy requires a ~5-days maturation process during which the genome-wide gene expression pattern gradually transitions from the ring-like state to a highly unique form. The transcriptome of the mature dormant stage carries hallmarks of cellular senescence with downregulation of most cellular functions associated with growth and development, but upregulation of selected metabolic functions and DNA repair. Moreover, the P. falciparum dormant stage is considerably more resistant to essentially all antimalaria drugs compared to the fast-growing asexual stages. Finally, the unique cellular ultrastructure further suggests unique properties of this new developmental stage of the P. falciparum life cycle that should be taken into consideration by new malaria control strategies.