Detection of Plasmodium falciparum K13 Propeller A569G Mutation after Artesunate-amodiaquine Treatment Failure in Niger

Background: Artemisinin (ART) resistance is a problem that may compromise the elimination of malaria. It is associated with point mutations in the kelch gene PF3D7_1343700 or K13 propeller (pfk13). A recent worldwide map of pfk13 polymorphisms revealed more than 100 non-synonymous (NS) mutations. However, it remains unclear whether these mutations are the result of drug pressure or the expression of a natural polymorphism, because of the scarcity of in-vivo selection of pfK13 mutations data in Africa.

Methodology: This survey evaluates the association between mutations in PfK13 and the response to treatment with artemether-lumefantrine (AL) and artesunate-amodiaquine (ASAQ) at Gaya, Niger. Mutations in PfK13 before and after treatment were analyzed and used as evidence for the selection of drug resistance following drug pressure.

Results: A total of 161 DNA from patients included in a therapeutic efficacy survey comparing AL vs ASAQ at Gaya sentinel site in 2011 were amplified and sequenced. Five SNPs were identified including 3 non-synonymous (NS) mutations (R528K, A569G and V637I) and 2 synonymous (SY) mutations (C469C and Q613Q). Four SNPs were observed prior to artemisinin-based Combination Therapy (ACT) including 2 NS (R528K and V637I) and 2 SY (C469C and Q613Q) mutations. One NS mutation was selected by ASAQ (PfK13A569G) whereas AL treatment did not select any mutation.

Conclusion: This study suggests that the mutation pfk13A569G is selected by ASAQ. Further mutagenesis studies (CRISPR/Cas9 or Z-Finger Nuclease) will be needed to confirm if pfk13A569G confers resistance to artemisinin.