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Genetic Studies of Vector Species

Genetic Studies of Vector Species

280 - Amplicon sequencing identifies novel insecticide resistance mutations associated with changes to PBO synergy in pyrethroid-resistant Anopheles gambiae s.l. from the Democratic Republic of Congo

Thursday, March 6, 2025
10:55 AM – 11:05 AM AST
Location: 209
Abstract: Resistance to pyrethroid insecticides used for malaria vector control is widespread in the Democratic Republic of the Congo (DRC), but there is a paucity of information regarding the molecular mechanisms driving resistance. Anopheles (An.) gambiae s.l. populations from eight study sites across the DRC were phenotyped for resistance to alpha-cypermethrin, deltamethrin and permethrin, with and without pre-exposure to the synergist PBO, followed by multiplex amplicon sequencing. Phenotypic resistance was confirmed to all three insecticides in all sites. In An. gambiae s.s. four non-synonymous SNPs identified were previously associated with insecticide resistance: gste2-L119V, vgsc-L995F, vgsc-L995S and rdl-A296G, while three were novel: gste2-T154S, ace1-N246T and ace1-P265L. Nationwide geographical trends in insecticide resistance mutation distribution, prevalence and selection were evident. In the West, near fixation of vgsc-L995F and almost complete absence of vgsc-L995S was observed, alongside low-moderate frequencies of rdl-A296G and gste2-L119V. Further East, the converse was apparent. Gste2-L119V and gste2-T154S were associated with variable response to pyrethroids, following PBO pre-exposure. Study findings comprise the most comprehensive overview of the prevalence of genetic markers of insecticide resistance across the DRC and provides an important baseline for improved malaria vector control and the design of proactive insecticide resistance management schemes.