In Vitro Confirmation of Artemisinin Resistance in Plasmodium falciparum from Patient Isolates, Southern Rwanda, 2019

Abstract

Artemisinin resistance in Plasmodium falciparum is conferred by mutations in the kelch 13 (K13) gene. In Rwanda, K13 mutations have increased over the past decade, including mutations associated with delayed parasite clearance. We document artemisinin resistance in P. falciparum patient isolates from Rwanda carrying K13 R561H, A675V, and C469F mutations.

Keywords: Kelch-13 gene mutations; Plasmodium falciparum; Rwanda; antimicrobial resistance; artemisinin resistance; malaria; parasites; vector-borne infections.

Figure 1

RSA 0–3-hour postinvasion survival rates (%) of an artemisinin-susceptible, K13 WT Plasmodium falciparum strain (NF54) and 4 P. falciparum patient isolates from Rwanda with K13 mutations. Each data point represents the mean of triplicate experiments. Isolate growth rates were only considered for analysis if 72-hour growth rates exceeded 1.5× rates in the nonexposed controls. Indicated error bars display the mean + SE; dashed line indicates the 1% survival rate threshold used to define artemisinin resistance (1,6). K13, kelch 13; RSA, ring-stage susceptibility assay; WT, wild-type.

Figure 2

IC₅₀ values for dihydroartemisinin for an artemisinin-susceptible, K13 WT Plasmodium falciparum strain (NF54) and in 4 P. falciparum patient isolates from Rwanda with K13 mutations. Indicated error bars display the mean + SE. p values were determined by Student t-test. IC₅₀, 50% inhibitory concentration; K13, kelch 13; WT, wild-type.