A single E205D allele of a key P450 CYP6P3 is driving metabolic pyrethroid resistance in the major African malaria vector Anopheles gambiae

Abstract

Deciphering the molecular drivers of insecticide resistance is paramount to extend the effectiveness of malaria vector control tools. Here, we demonstrated that the E205D amino acid change in a key metabolic resistance P450 CYP6P3 drives pyrethroid resistance in the major malaria vector, Anopheles gambiae. Spatio-temporal whole genome Poolseq analyses in Cameroon detected a major P450-linked locus on chromosome 2R beside the sodium channel locus. In vitro metabolism assays with recombinantly expressed CYP6P3 protein revealed that the catalytic efficiency of 205D was 2.5 times higher than E205 with -cypermethrin. Similar patterns were observed for permethrin. Overexpression of the 205D allele in transgenic flies confers higher more pyrethroids and carbamates resistance, compared to controls. A DNA-based assay further supported that the CYP6P3-205D variant strongly correlates with pyrethroid resistance in field populations (OR=26.4; P<0.0001) and that it reduces the efficacy of pyrethroid-only LLINs with homozygote RR genotype exhibiting significantly higher survival following PermaNet 3.0 exposure compared to the SS genotype (OR: 6.1, p = 0.0113). Furthermore, the CYP6P3-E205D combines with the kdr target-site resistance mechanisms to worsen the loss of bednet efficacy. The 205D mutation is now predominant in West and Central Africa but less abundant or absent in East and South Africa with signs of introgression with An. coluzzii in Ghana. This study highlights the importance of P450-based resistance and designs field-applicable tools to easily track the spread of metabolic resistance and assess its impact on control interventions. One Sentence Summary: The major obstacle to malaria control and elimination is the spread of parasite resistance to anti-malarial drugs, and mosquito resistance to insecticides. In this study, we identified a key point mutation E205D in the metabolic gene CYP6P3 (cytochrome P450) conferring resistance to pyrethroids by enhancing the breakdown of insecticides used for bednets impregnation. DNA-based assays were then designed and used to determine the spread of the resistance across Africa and demonstrate that the CYP6P3-205D allele works together with the knockdown resistance in the voltage-gated Sodium channel to reduce the efficacy of insecticide-treated bednets.