Study develops CRISPR gene editing to combat insecticide resistance

An international study has introduced an innovative gene-editing system based on CRISPR technology. 

Researchers were able to reverse insecticide resistance in populations of the fruit fly species Drosophila melanogaster.

The technology has potential applications in controlling vectors of infectious diseases and agricultural pests. The study was published in Nature Communications, part of the Nature Group. It was conducted by researchers from the University of California, San Diego (UCSD) in collaboration with a professor from the Institute of Biomedical Sciences at the University of São Paulo (ICB-USP), Brazil.

The tool used, called a gene-drive system, works by favoring the spread of a specific gene within a target population. In the experiment, the system was programmed to identify and replace the DNA segment associated with insecticide resistance.

"The gene drive recognizes and breaks a specific region of the DNA that contains unwanted information. Through natural cellular repair mechanisms, the DNA can reassemble itself by copying another piece of information that it aims to propagate. This is the mechanism used to reverse insecticide resistance in insect populations," explained Rodrigo Corder, professor in the Department of Parasitology at ICB-USP and one of the study's collaborators.

The advantage of the gene drive lies in its genetic transmission pattern. Under natural conditions, Mendelian inheritance dictates that 50% of the offspring inherit a specific gene. With the gene drive, this number can rise to nearly 100%, accelerating the spread of the desired trait in the target population.

"A small number of modified individuals can, over a few generations, genetically alter an entire population. This makes the technique a promising alternative for vector control of infectious diseases and for managing insecticide resistance in agricultural insects, for example," the researcher said.

One of the distinguishing features of this research is the method's reduced ecological impact. Previous studies using gene drive succeeded in spreading genes in insect populations, but the genetic changes remained indefinitely in the studied populations. 

In this new study, researchers refined the genetic system so that, in addition to reversing insecticide resistance, the other introduced genetic changes naturally disappear over time.

"In our application, this happens because female Drosophila showed a reproductive preference for non-mutant males, causing the population to gradually return to its original state after the reversal of insecticide resistance. In other words, the genetic components introduced and responsible for spreading the desired trait (Cas9 protein and guide RNA) are naturally eliminated over generations. This behavior tends to minimize the ecological impact of the application, as the introduced mutations are transient," Corder explained.

The study was led by Professor Ethan Bier from UC San Diego, with researcher Ankush Auradkar as the first author. Corder and Bier began collaborating during Corder's postdoctoral work at the University of California, Berkeley, under the supervision of Professor John Marshall. Since then, Corder and Marshall have collaborated on the mathematical modeling component to predict the spread dynamics of these genetic traits in the studied insect populations.

"Mathematical modeling plays an essential role in understanding how these genetic modifications propagate over time and evaluating their feasibility before potential applications in natural environments," he added.

Although this research focused on insecticide resistance in fruit flies, previous studies have already demonstrated the potential of gene drive for controlling vectors of diseases like malaria, reducing their ability to transmit the parasite. The research has sparked international interest and was highlighted, for example, by the KPBS broadcaster in the United States, underscoring its relevance to the global scientific community.

″The study contributes to the development of safer and more efficient vector control strategies, paving the way for new applications in combating diseases such as dengue, malaria, and other insect-borne infections,″ Academic Communication Agency said in conclusion.

(Editing by Leonardo Gottems, reporter for AgroPages)