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Hancock PA, Ochomo E, Messenger LA. Genetic surveillance of insecticide resistance in African Anopheles populations to inform malaria vector control. Trends Parasitol 2024; 40:604-618. [PMID: 38760258 DOI: 10.1016/j.pt.2024.04.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/24/2024] [Accepted: 04/26/2024] [Indexed: 05/19/2024]
Abstract
Insecticide resistance in malaria vector populations poses a major threat to malaria control, which relies largely on insecticidal interventions. Contemporary vector-control strategies focus on combatting resistance using multiple insecticides with differing modes of action within the mosquito. However, diverse genetic resistance mechanisms are present in vector populations, and continue to evolve. Knowledge of the spatial distribution of these genetic mechanisms, and how they impact the efficacy of different insecticidal products, is critical to inform intervention deployment decisions. We developed a catalogue of genetic-resistance mechanisms in African malaria vectors that could guide molecular surveillance. We highlight situations where intervention deployment has led to resistance evolution and spread, and identify challenges in understanding and mitigating the epidemiological impacts of resistance.
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Affiliation(s)
- Penelope A Hancock
- Department of Infectious Disease Epidemiology, Imperial College London, London, UK.
| | - Eric Ochomo
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya; Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Louisa A Messenger
- Department of Environmental and Occupational Health, School of Public Health, University of Nevada, Las Vegas, USA; Parasitology and Vector Biology (PARAVEC) Laboratory, School of Public Health, University of Nevada, Las Vegas, USA
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Sadia CG, Bonneville JM, Zoh MG, Fodjo BK, Kouadio FPA, Oyou SK, Koudou BG, Adepo-Gourene BA, Reynaud S, David JP, Mouahamadou CS. The impact of agrochemical pollutant mixtures on the selection of insecticide resistance in the malaria vector Anopheles gambiae: insights from experimental evolution and transcriptomics. Malar J 2024; 23:69. [PMID: 38443984 PMCID: PMC10916200 DOI: 10.1186/s12936-023-04791-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 11/14/2023] [Indexed: 03/07/2024] Open
Abstract
BACKGROUND There are several indications that pesticides used in agriculture contribute to the emergence and spread of resistance of mosquitoes to vector control insecticides. However, the impact of such an indirect selection pressure has rarely been quantified and the molecular mechanisms involved are still poorly characterized. In this context, experimental selection with different agrochemical mixtures was conducted in Anopheles gambiae. The multi-generational impact of agrochemicals on insecticide resistance was evaluated by phenotypic and molecular approaches. METHODS Mosquito larvae were selected for 30 generations with three different agrochemical mixtures containing (i) insecticides, (ii) non-insecticides compounds, and (iii) both insecticide and non-insecticide compounds. Every five generations, the resistance of adults to deltamethrin and bendiocarb was monitored using bioassays. The frequencies of the kdr (L995F) and ace1 (G119S) target-site mutations were monitored every 10 generations. RNAseq was performed on all lines at generation 30 in order to identify gene transcription level variations and polymorphisms associated with each selection regime. RESULTS Larval selection with agrochemical mixtures did not affect bendiocarb resistance and did not select for ace1 mutation. Contrastingly, an increased deltamethrin resistance was observed in the three selected lines. Such increased resistance was not majorly associated with the presence of kdr L995F mutation in selected lines. RNA-seq identified 63 candidate resistance genes over-transcribed in at least one selected line. These include genes coding for detoxification enzymes or cuticular proteins previously associated with insecticide resistance, and other genes potentially associated with chemical stress response. Combining an allele frequency filtering with a Bayesian FST-based genome scan allowed to identify genes under selection across multiple genomic loci, supporting a multigenic adaptive response to agrochemical mixtures. CONCLUSION This study supports the role of agrochemical contaminants as a significant larval selection pressure favouring insecticide resistance in malaria vectors. Such selection pressures likely impact kdr mutations and detoxification enzymes, but also more generalist mechanisms such as cuticle resistance, which could potentially lead to cross-tolerance to unrelated insecticide compounds. Such indirect effect of global landscape pollution on mosquito resistance to public health insecticides deserves further attention since it can affect the nature and dynamics of resistance alleles circulating in malaria vectors and impact the efficacy of control vector strategies.
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Affiliation(s)
- Christabelle G Sadia
- University of Nangui Abrogoua, Abidjan, Côte d'Ivoire.
- Centre Suisse de Recherches Scientifiques (CSRS), Abidjan, Côte d'Ivoire.
| | - Jean-Marc Bonneville
- Laboratoire d'Ecologie Alpine (LECA) UMR 5553, Univ. Grenoble-Alpes, Univ. Savoie Mont Blanc, CNRS, 38000, Grenoble, France
| | - Marius G Zoh
- Laboratoire d'Ecologie Alpine (LECA) UMR 5553, Univ. Grenoble-Alpes, Univ. Savoie Mont Blanc, CNRS, 38000, Grenoble, France
- Vector Control Product Evaluation Centre (VCPEC)/Institut Pierre Richet, Bouaké, Côte d'Ivoire
| | - Behi K Fodjo
- Centre Suisse de Recherches Scientifiques (CSRS), Abidjan, Côte d'Ivoire
| | - France-Paraudie A Kouadio
- University of Nangui Abrogoua, Abidjan, Côte d'Ivoire
- Centre Suisse de Recherches Scientifiques (CSRS), Abidjan, Côte d'Ivoire
| | - Sebastien K Oyou
- Centre Suisse de Recherches Scientifiques (CSRS), Abidjan, Côte d'Ivoire
| | - Benjamin G Koudou
- University of Nangui Abrogoua, Abidjan, Côte d'Ivoire
- Centre Suisse de Recherches Scientifiques (CSRS), Abidjan, Côte d'Ivoire
| | | | - Stephane Reynaud
- Laboratoire d'Ecologie Alpine (LECA) UMR 5553, Univ. Grenoble-Alpes, Univ. Savoie Mont Blanc, CNRS, 38000, Grenoble, France
| | - Jean-Philippe David
- Laboratoire d'Ecologie Alpine (LECA) UMR 5553, Univ. Grenoble-Alpes, Univ. Savoie Mont Blanc, CNRS, 38000, Grenoble, France
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Fotso-Toguem Y, Tene-Fossog B, Mugenzi LMJ, Wondji MJ, Njiokou F, Ranson H, Wondji CS. Genetic Diversity of Cytochrome P450s CYP6M2 and CYP6P4 Associated with Pyrethroid Resistance in the Major Malaria Vectors Anopheles coluzzii and Anopheles gambiae from Yaoundé, Cameroon. Genes (Basel) 2022; 14:52. [PMID: 36672793 PMCID: PMC9858699 DOI: 10.3390/genes14010052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/14/2022] [Accepted: 12/19/2022] [Indexed: 12/28/2022] Open
Abstract
Assessing the genetic diversity of metabolic resistance genes, such as cytochrome P450s, helps to understand the dynamics and evolution of resistance in the field. Here, we analyzed the polymorphisms of CYP6M2 and CYP6P4, associated with pyrethroid resistance in Anopheles coluzzii and Anopheles gambiae, to detect potential resistance markers. Field-caught resistant mosquitos and susceptible lab strains were crossed, and F4 was exposed to permethrin for 15 min and 90 min to discriminate highly susceptible (HS) and highly resistant (HR) mosquitos, respectively. Significant permethrin mortality reduction was observed after pre-exposure to PBO, suggesting the gene involvement of P450s. qPCR analysis revealed significant overexpression of CYP6M2 (FC = 19.57 [95% CI 13.96-25.18] for An. coluzzii; 10.16 [7.86-12.46] for An. gambiae) and CYP6P4 (FC = 6.73 [6.15-7.30] An. coluzzii; 23.62 [26.48-20.76] An. gambiae). Full-gene and ≈1 kb upstream were sequenced. For CYP6M2, the upstream region shows low diversity in HR and HS (overall Hd = 0.49, π = 0.018), whereas the full-gene shows allelic-variation but without evidence of ongoing selection. CYP6P4 upstream region showed a lower diversity in HR (Hd = 0.48) than HS (Hd = 0.86) of An. gambiae. These results highlighted that CYP6P4-associated resistance is potentially driven by modification in upstream region. However, further work is needed to determine the real causative variants that will help design rapid detection tools.
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Affiliation(s)
- Yvan Fotso-Toguem
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé P.O. Box 812, Cameroon
| | - Billy Tene-Fossog
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon
| | - Leon M. J. Mugenzi
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon
| | - Murielle J. Wondji
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L35QA, UK
| | - Flobert Njiokou
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé P.O. Box 812, Cameroon
| | - Hilary Ranson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L35QA, UK
| | - Charles S. Wondji
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L35QA, UK
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Wamba ANR, Ibrahim SS, Kusimo MO, Muhammad A, Mugenzi LMJ, Irving H, Wondji MJ, Hearn J, Bigoga JD, Wondji CS. The cytochrome P450 CYP325A is a major driver of pyrethroid resistance in the major malaria vector Anopheles funestus in Central Africa. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2021; 138:103647. [PMID: 34530119 DOI: 10.1016/j.ibmb.2021.103647] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/20/2021] [Accepted: 09/07/2021] [Indexed: 06/13/2023]
Abstract
The overexpression and overactivity of key cytochrome P450s (CYP450) genes are major drivers of metabolic resistance to insecticides in African malaria vectors such as Anopheles funestus s.s. Previous RNAseq-based transcription analyses revealed elevated expression of CYP325A specific to Central African populations but its role in conferring resistance has not previously been demonstrated. In this study, RT-qPCR consistently confirmed that CYP325A is highly over-expressed in pyrethroid-resistant An. funestus from Cameroon, compared with a control strain and insecticide-unexposed mosquitoes. A synergist bioassay with PBO significantly recovered susceptibility for permethrin and deltamethrin indicating P450-based metabolic resistance. Analyses of the coding sequence of CYP325A Africa-wide detected high-levels of polymorphism, but with no predominant alleles selected by pyrethroid resistance. Geographical amino acid changes were detected notably in Cameroon. In silico homology modelling and molecular docking simulations predicted that CYP325A binds and metabolises type I and type II pyrethroids. Heterologous expression of recombinant CYP325A and metabolic assays confirmed that the most-common Cameroonian haplotype metabolises both type I and type II pyrethroids with depletion rate twice that the of the DR Congo haplotype. Analysis of the 1 kb putative promoter of CYP325A revealed reduced diversity in resistant mosquitoes compared to susceptible ones, suggesting a potential selective sweep in this region. The establishment of CYP325A as a pyrethroid resistance metabolising gene further explains pyrethroid resistance in Central African populations of An. funestus. Our work will facilitate future efforts to detect the causative resistance markers in the promoter region of CYP325A to design field applicable DNA-based diagnostic tools.
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Affiliation(s)
- Amelie N R Wamba
- Centre for Research in Infectious Diseases (CRID), P.O. BOX 13591, Yaoundé, Cameroon; Faculty of Science, Department of Biochemistry, University of Yaoundé I, P.O. Box 812, Yaoundé, Cameroon.
| | - Sulaiman S Ibrahim
- Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Pembroke Place, Liverpool, L3 5QA, UK; Department of Biochemistry, Bayero University, PMB, 3011, Kano, Nigeria.
| | - Michael O Kusimo
- Centre for Research in Infectious Diseases (CRID), P.O. BOX 13591, Yaoundé, Cameroon.
| | - Abdullahi Muhammad
- Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Pembroke Place, Liverpool, L3 5QA, UK; Centre for Biotechnology Research, Bayero University, Kano, PMB, 3011, Kano Nigeria.
| | - Leon M J Mugenzi
- Centre for Research in Infectious Diseases (CRID), P.O. BOX 13591, Yaoundé, Cameroon; Department of Biochemistry and Molecular Biology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon.
| | - Helen Irving
- Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Pembroke Place, Liverpool, L3 5QA, UK.
| | - Murielle J Wondji
- Centre for Research in Infectious Diseases (CRID), P.O. BOX 13591, Yaoundé, Cameroon; Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Pembroke Place, Liverpool, L3 5QA, UK.
| | - Jack Hearn
- Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Pembroke Place, Liverpool, L3 5QA, UK.
| | - Jude D Bigoga
- Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Pembroke Place, Liverpool, L3 5QA, UK; Laboratory for Vector Biology and Control, National Reference Unit for Vector Control, The Biotechnology Centre, Nkolbisson - University of Yaoundé I, P.O. Box 3851, Messa, Yaoundé, Cameroon.
| | - Charles S Wondji
- Centre for Research in Infectious Diseases (CRID), P.O. BOX 13591, Yaoundé, Cameroon; Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Pembroke Place, Liverpool, L3 5QA, UK.
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