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The G119S Acetylcholinesterase (Ace-1) Target Site Mutation Confers Carbamate Resistance in the Major Malaria Vector Anopheles gambiae from Cameroon: A Challenge for the Coming IRS Implementation

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Centre for Research in Infectious Diseases (CRID), P.O. BOX 13591, Yaoundé, Cameroon
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Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, P.O. Box 812, Yaoundé, Cameroon
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Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, P.O. Box 24157, Douala, Cameroon
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Department of Animal Biology, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon
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Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
*
Author to whom correspondence should be addressed.
Genes 2019, 10(10), 790; https://doi.org/10.3390/genes10100790
Received: 31 August 2019 / Revised: 6 October 2019 / Accepted: 8 October 2019 / Published: 11 October 2019
(This article belongs to the Section Molecular Genetics and Genomics)
Growing resistance is reported to carbamate insecticides in malaria vectors in Cameroon. However, the contribution of acetylcholinesterase (Ace-1) to this resistance remains uncharacterised. Here, we established that the G119S mutation is driving resistance to carbamates in Anopheles gambiae populations from Cameroon. Insecticide bioassay on field-collected mosquitoes from Bankeng, a locality in southern Cameroon, showed high resistance to the carbamates bendiocarb (64.8% ± 3.5% mortality) and propoxur (55.71% ± 2.9%) but a full susceptibility to the organophosphate fenitrothion. The TaqMan genotyping of the G119S mutation in field-collected adults revealed the presence of this resistance allele (39%). A significant correlation was observed between the Ace-1R and carbamate resistance at allelic ((bendiocarb; odds ratio (OR) = 75.9; p < 0.0001) and (propoxur; OR = 1514; p < 0.0001)) and genotypic (homozygote resistant vs. homozygote susceptible (bendiocarb; OR = 120.8; p < 0.0001) and (propoxur; OR = 3277; p < 0.0001)) levels. Furthermore, the presence of the mutation was confirmed by sequencing an Ace-1 portion flanking codon 119. The cloning of this fragment revealed a likely duplication of Ace-1 in Cameroon as mosquitoes exhibited at least three distinct haplotypes. Phylogenetic analyses showed that the predominant Ace-1R allele is identical to that from West Africa suggesting a recent introduction of this allele in Central Africa from the West. The spread of this Ace-1R represents a serious challenge to future implementation of indoor residual spraying (IRS)-based interventions using carbamates or organophosphates in Cameroon.
Keywords: Ace-1 G119S mutation; insecticide resistance; Anopheles gambiae; Cameroon; malaria Ace-1 G119S mutation; insecticide resistance; Anopheles gambiae; Cameroon; malaria
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Elanga-Ndille, E.; Nouage, L.; Ndo, C.; Binyang, A.; Assatse, T.; Nguiffo-Nguete, D.; Djonabaye, D.; Irwing, H.; Tene-Fossog, B.; Wondji, C.S. The G119S Acetylcholinesterase (Ace-1) Target Site Mutation Confers Carbamate Resistance in the Major Malaria Vector Anopheles gambiae from Cameroon: A Challenge for the Coming IRS Implementation. Genes 2019, 10, 790.

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