Journal of Mosquito Research 2024, Vol.14, No.3, 124-134 http://emtoscipublisher.com/index.php/jmr 127 Adolfi et al. (2020) found that using a gene-drive system in mosquitoes can effectively target and replace specific gene sequences, potentially providing a method to combat vector-borne diseases like malaria. The researchers utilized a Cas9/gRNA-mediated cassette exchange strategy to insert a GFP-marked donor template, restoring the function of the kh gene while rendering it resistant to the gene drive. This approach involved creating a homology-directed repair (HDR) template to promote precise integration and maintain gene function. They demonstrated that the insertion of this unit can be accurately achieved, with the potential for disrupting gene function through end-joining (EJ) pathways. This innovative method could significantly impact the genetic control of mosquito populations, providing a pathway to reducing the transmission of malaria by impairing the reproductive capabilities of the mosquito vectors. 4 Case Studies 4.1 Case study: Aedes aegypti control in Brazil In Brazil, the control of Aedes aegypti, the primary vector for dengue, Zika, and chikungunya viruses, has been a significant public health challenge. Various genetic control techniques have been employed to mitigate the spread of these diseases. One notable approach involves the release of genetically modified mosquitoes designed to reduce the population of Aedes aegypti through the introduction of lethal genes. This method has shown promise in reducing mosquito populations and, consequently, the incidence of mosquito-borne diseases. The success of these interventions in Brazil underscores the potential of genetic control techniques in managing mosquito populations and reducing disease transmission (Figure 2) (Garcia et al., 2019). Figure 2 Pyrethroid resistance in two Wolbachia-infected strains (wMelBr and wMelRio) and three field Aedes aegypti populations (Tubiacanga, Jurujuba and Urca) (Adopted from Garcia et al., 2019) Image caption: The susceptible strain Rockefeller was used as a calibration control. A) Mortality profile of Ae. aegypti adult females exposed to the pyrethroid deltamethrin. B) Allelic frequency of population samples; numbers above bars indicate the sum of ‘resistance genotypes’ to pyrethroids, In blue NaVS (1016 Val+ + 1534 Phe+), in orange NaVR1 (1016 Val+ + 1534 Cyskdr) and in red NaVR2 (1016 Ilekdr + 1534 Cyskdr) (Adapted from Garcia et al., 2019) Garcia et al. (2019) found that two Wolbachia-infected Aedes aegypti strains, wMelBr and wMelRio, and three field populations from Tubiacanga, Jurujuba, and Urca displayed varying levels of resistance to the pyrethroid insecticide deltamethrin. The study revealed that mortality rates among these populations differed significantly
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