Investigating the presence of Pfkelch gene mutations in Ugandan children with severe malaria

Abstract

Artemisinin resistance was first observed in Southeast Asia (SEA) and could pose a threat to malaria treatment all over the world. Recently mutations in the propeller region of Pfkelch13 gene have been used as a genetic marker for resistance observed in SEA. We investigated the presence of mutations in the Pfkelch gene in children in Kampala, Uganda with severe malaria (SM) treated with intravenous quinine, or with asymptomatic P.falciparum infection (AP) treated with artemether-lumefantrine. We sequenced the Pfkelch gene (2178bp) in 157 children with SM and 49 children with AP infection. In children with SM and AP we identified 106 (60.8%) and 27 (55.1%) parasites with mutations upstream of the Pfkelch13 propeller region. The two most prevalent mutations were 142NN (26.1% in SM, 33% in AP) and K189T (16.5% in SM, 12.2% in AP). In SM, only a single infection had a mutation in the propeller region (A578S), while in AP, mutations in the propeller region included A578S (n=1) and S522C (n=1). In children with SM, parasites with 142NN insertion compared to 3D7 Pfkelch13 parasites had lower parasite density (p=0.02) and lower parasite biomass (p=0.03). Children with SM who either had 142NN or K189T mutation cleared parasites after quinine treatment faster than those with the 3D7 Pfkelch13 genotype (P<0.001 for both mutations compared to 3D7). In this cohort mutations, upstream of the Pfkelch13 propeller region were common. Future studies will assess the presence of Pfcrt and Pfmdr mutations in this cohort, and how these relate to the Pfkelch13 mutations and to parasite clearance.