Conditional expression of Nix in transgenic Aedes aegypti

Aedes aegypti, the main vector of dengue, yellow fever, and other arboviruses, have a wide distribution, thriving in tropical and subtropical areas around the globe and putting half of the world’s population at risk. Despite aggressive efforts to control the transmission of those viruses, an unacceptable number of cases occur every year, emphasizing the need to develop new control strategies. Proposals for vector control focused on population suppression could offer a feasible alternative method to affect disease transmission. The induction of extreme male-biased reproductive sex ratios has been hypothesized to be able to suppress or collapse a population. Here, we report on the conditional expression of the male determining factor Nix through the Tet off system in transgenic Aedes aegypti. Transposon-based methods were used to generate the transgenic lines and RT-qPCR methods to determine the level of Nix transcript accumulation under doxycycline-mediated regulation. Blood feeding success, maxillary palps length, and body size were used as a proxy for the masculinization level of transgenic females. Seven transgenic lines carrying the conditional expression of Nix constructs were obtained. A masculinization phenotype was observed in three of the seven transgenic lines with females exhibiting long maxillary palps and most important, the masculinized females we unable to blood feed. RT-qPCR analysis showed that there was no correlation between the level of masculinization and ectopic Nix expression. This study is one step forward in the development of genetic strategies to control vector-borne diseases.