Multiplex high resolution melting PCR for simultaneous genotyping of pyrethroid-resistance associated mutations in Aedes aegypti. First report on kdr mutations in wild populations from Argentina

Background Aedes aegypti is an urban mosquito vector of Dengue and other arboviruses. During epidemic periods, pyrethroid insecticides are used for the control of adult mosquitoes; the worldwide distributed resistance to these insecticides is a cause of failures in vector control campaigns. The primary target of pyrethroids is the voltage-gated sodium channel; point mutations on this channel, called kdr mutations, are associated with pyrethroid resistance. Two kdr mutations, called V1016I and F1534C, augmented in frequency in natural populations of Ae. aegypti from the Americas in the last decade. The diagnostic of kdr polymorphisms allows an early detection of insecticide resistance spreading, which is critical for timely decisions on vector management. Given the relevance of resistance management, high-throughput methods for kdr genotyping are invaluable tools for resistance monitoring programs. These methods should also be cost-effective, to allow regional-scale surveys. Despite the extended presence of Ae. aegypti and the incidence of dengue in Argentina, the presence, abundance and distribution of kdr mutations were not reported in this country up to date. Methodology and findings We report a multiplex high-throughput assay based in High Resolution Melting PCR for the simultaneous genotyping of 1016 and 1534 sites in voltage-gated sodium channel gene. We used this method for the study of individual mosquito samples collected in localities which received different selection pressure with pyrethroids. Compared to other genotyping methods, multiplex High Resolution Melting was high-throughput, cost-efficient, sensitive and specific. We demonstrate for the first time the presence of kdr mutations in Argentina in regions under different selection pressure with pyrethroids. Conclusions and Significance We have developed a high-throughput method for the genotyping of alleles associated with pyrethroid resistance in Ae. aegypti from the American continent. The method developed here is comparable in its sensitivity and reliability with other genotyping methods, but reduces costs and running time. It could be incorporated in control campaigns for control the presence and spreading of resistance-associated alleles. We report here for the first time the presence of kdr mutations in distant populations from Argentina, with different epidemiological situations and different history of mosquito control efforts. Authors summary Aedes aegypti is a mosquito vector of viruses such as dengue, causing millions of infections yearly worldwide. Emergence and distribution of insecticide resistance in this mosquito is a challenge for control campaigns. In this context, the implementation of resistance management strategies became a requisite for successful and sustainable mosquito management. To achieve this objective, it is important to count with early genetic markers of resistance, such as kdr mutations, which are associated with pyrethroid resistance phenotype. Kdr markers can be detected by molecular genotyping diagnostic at early stages in the emergence of resistance; this information should be considered in rational design of control campaigns. Here we present a high-throughput cost-effective method to detect kdr mutations in Ae. aegypti. Also, we demonstrate for the first time the presence of kdr mutations in Argentina.