Kouamo Mersimine F M, Ibrahim Sulaiman S, Muhammad Abdullahi, Gadji Mahamat, Hearn Jack, Wondji Charles S
Centre for Research in Infectious Diseases (CRID), P.O. Box 13591, Yaoundé, Cameroon.
Department of Biochemistry, Bayero University, PMB, 3011, Kano, Nigeria.
BMC Genomics. 2025 May 7;26(1):452. doi: 10.1186/s12864-025-11637-3.
Insecticide resistance in malaria vectors is a serious challenge to malaria control and elimination. Elucidation of the role of detoxification genes in resistance is necessary to develop targeted strategies to reduce malaria burden. Glutathione S-transferase epsilon clusters (GSTe genes) are upregulated in DDT- and pyrethroid-resistant Anopheles funestus mosquitoes across Africa. However, except for GSTe2, the molecular mechanisms behind this upregulation remain unclear. Here, we established that overexpression and allelic variation of GSTe genes contribute to insecticide resistance in African malaria vector An. funestus s.s.
Transcriptomic and genomic analyses of GSTe genes were conducted, followed by in silico structural analysis, and functional characterization of GSTe3, GSTe4 and GSTe6 using metabolic assay and transgenic expression in Drosophila flies.
Transcriptomic and genomic analyses reveal changes in gene expression and genetic diversity of GSTes cluster in An. funestus across Africa. Cloning of cDNAs of GSTes from different regions of Africa detected allelic variants under selection, including ADT-GSTe3, LHA-GSTe4 in West/Central Africa, and TS E-GSTe6 present only in West/Southern Africa. Furthermore, in silico analysis of BN-GSTe3, MWI-GSTe3, BN-GSTe4, MWI-GSTe4, CMR-GSTe6 and, BN-GSTe6 alleles revealed that allelic variations increase the binding cavity in the active site of these GSTes with stronger affinities observed towards DDT and permethrin. All recombinant GSTes significantly metabolize DDT (41-63%) and permethrin (13-25%). Additionally, BN-GSTe4 (LHA-GSTe4) variant significantly metabolizes deltamethrin (28.75%), compared to the wild-type allele (15.99%; p < 0.05). Transgenic expression of the GSTes in Drosophila melanogaster flies revealed reduced DDT mortalities in flies expressing the selected alleles (39-55%; p˂0.001), compared to control group (98%). Similar resistance patterns were observed toward permethrin and deltamethrin.
These findings established the role of GSTes in conferring cross-resistance to pyrethroids and DDT, highlighting the role of these genes in metabolic resistance in An. funestus, which complicates malaria control using the above key insecticides.
疟疾病媒的杀虫剂抗性是疟疾控制和消除面临的严峻挑战。阐明解毒基因在抗性中的作用对于制定减轻疟疾负担的靶向策略至关重要。谷胱甘肽S-转移酶ε簇（GSTe基因）在非洲对滴滴涕和拟除虫菊酯具有抗性的冈比亚按蚊中上调。然而，除了GSTe2外，这种上调背后的分子机制仍不清楚。在此，我们证实GSTe基因的过表达和等位基因变异导致非洲疟疾病媒冈比亚按蚊指名亚种产生杀虫剂抗性。
对GSTe基因进行转录组和基因组分析，随后进行计算机结构分析，并使用代谢测定和果蝇转基因表达对GSTe3、GSTe4和GSTe6进行功能表征。
转录组和基因组分析揭示了非洲各地冈比亚按蚊中GSTe簇的基因表达和遗传多样性变化。从非洲不同地区克隆GSTe的cDNA，检测到处于选择中的等位基因变体，包括西非/中非的ADT-GSTe3、LHA-GSTe4，以及仅在西非/南非存在的TS E-GSTe6。此外，对BN-GSTe3、MWI-GSTe3、BN-GSTe4、MWI-GSTe4、CMR-GSTe6和BN-GSTe6等位基因的计算机分析表明，等位基因变异增加了这些GSTe活性位点的结合腔，对滴滴涕和氯菊酯具有更强的亲和力。所有重组GSTe均能显著代谢滴滴涕（41%-63%）和氯菊酯（13%-25%）。此外，与野生型等位基因（15.99%；p<0.05）相比，BN-GSTe4（LHA-GSTe4）变体对溴氰菊酯的代谢能力显著增强（28.75%）。在黑腹果蝇中对GSTe进行转基因表达，结果显示与对照组（98%）相比，表达所选等位基因的果蝇对滴滴涕的死亡率降低（39%-55%；p<0.001）。对氯菊酯和溴氰菊酯也观察到类似的抗性模式。
这些发现确定了GSTe在赋予对拟除虫菊酯和滴滴涕的交叉抗性中的作用，突出了这些基因在冈比亚按蚊代谢抗性中的作用，这使得使用上述关键杀虫剂控制疟疾变得更加复杂。
