Genetic background determines allele-specific Pfkelch13 -mediated artemisinin tolerance and persistence in Plasmodium falciparum.

Artemisinin-based combination therapies are the frontline treatment for Plasmodium falciparum malaria, but their efficacy is threatened by Artemisinin partial resistance (ART R ). ART R in Plasmodium falciparum is mediated by Pfkelch13 ( k13 ) mutations but remains rare in West Africa. A critical question is whether short-term drug survival intrinsically predicts long-term evolutionary persistence. Here, using CRISPR-Cas9 editing, and nanopore-assisted allele tracking in a contemporary Senegalese isolate, we evaluated ART R receptivity using the ring-stage survival assay (RSA), a proxy for clinical resistance. We demonstrate that ART R survival and drug-free persistence are biologically separable traits. While the WHO-validated Asian I543T mutation conferred the RSA phenotype, it was rapidly counter-selected during drug-free growth. In contrast, emerging African alleles (R561H, M579I) and a regional novel variant (C473S) establish stable resistance without a competitive penalty. These findings reveal that a parasite's genetic background acts as a strict evolutionary filter, uncoupling short-term tolerance from long-term persistence and establishing that genomic context determines allele-specific resistance trajectories.