On Thursday, June 8th, 2023, Mr. Mbakam Leuze Patrick Bertrand, a Laboratory Technician at CRID, successfully defended his Master’s dissertation in Biochemistry at the University of Yaoundé I on the topic: “(Uridine-Diphosphate) UDP-Glycosyltransferase Genes in the Primary Malaria Vector, Anopheles funestus, and: Potential Contribution to Pyrethroid Resistance”. The aim of this study was to determine the contribution of UDP-Glycosyltransferase to pyrethroid resistance in one major African malaria vector, An. funestus. Specifically, Bertrand determined the susceptibility profile to pyrethroids of Anopheles funestus mosquitoes from Mibellon (Adamaoua region, Cameroon); evaluate the level of expression of UDP-Glycosyltransferase in resistant mosquitoes, analyse its genetic diversity, and search for potential markers associated with resistance.
Indoor resting adult mosquitoes (F0) were collected in Mibellon and reared at the CRID’s insectary, the emerging progeny (F1) was used for insecticide susceptibility tests following the World Health Organization (WHO) protocol. Mosquitoes that survive exposure to Deltamethrin and Permethrin insecticides were analysed for the detection of resistance mechanisms. The expression level of candidate UDP-Glycosyltransferase genes (AFUN004354) identified by RNASeq in 2018 to be potentially involved in insecticide resistance was assessed using quantitative real-time (PCR RT-qPCR). Finally, the candidate gene was amplified, cloned, and sequenced to assess the polymorphism of this gene and look for potential genetic variations associated with resistance. The results of susceptibility tests revealed that this population was resistant to all the pyrethroids, with the following mortality rates: Deltamethrin 1x: 19.44 ± 2.78%, Deltamethrin 5x: 53.68 ± 8.22%, Deltamethrin 10x: 89.75 ± 2.25%, and Permethrin 1x: 20.47 ± 6.86%, Permethrin 5x: 68.34 ± 2.62%, and Permethrin 10x: 83.41 ± 4.25%.
Malaria control is mainly based on vector control, which is the cornerstone method to fight against this parasitic disease. This is achieved by the use of insecticides through indoor residual spraying and long-lasting insecticidal nets (LLINs). However, the effectiveness of these control tools is threatened by the emergence and growth of resistance in malaria vectors to most of the insecticides used in public health like pyrethroids, which is the main class of insecticide used to impregnate mosquito nets, represented here by Deltamethrin and Permethrin. Insecticide resistance has been reported in the major vectors Anopheles gambiae s.l and Anopheles funestus s.l in several African countries, including Cameroon.
