Scientists have eradicated a population of malaria-transmitting mosquitoes by using genetic engineering to make the females infertile — in what the lead researcher called a possible “game-changer in bringing about malaria elimination.”
A team of researchers — led by scientists at Imperial College London, Italy’s Polo Genomics Genetics and Biology, and the Liverpool School of Tropical Medicine — used the “gene drive” technology for the study, which was published in Nature Communications.
“Gene drive is a self-sustaining and fast-acting technology that can work alongside existing tools such as bed nets, insecticides and vaccines — and could be a game-changer in bringing about malaria elimination,” Andrew Hammond, a molecular biologist at Imperial College London, told the Guardian.
Using the technology, scientists may circumvent natural selection by providing genetic instructions that will spread through a mosquito population and pass on a particular trait — in this case, infertility — much faster than could be attained through regular selective breeding, the outlet said.
But in addition to bringing fresh hope in the fight against malaria, the study lays the foundations for trials that could result in self-destroying mosquitoes being released into the wild within 10 years.
“This is a very exciting development,” Thomas Price, a senior lecturer in evolution, ecology and behavior at the University of Liverpool, told the news outlet.
“This is a major step towards achieving that.”
However, Price, who was not involved in the study, noted that “there are still lots of ethical and regulatory questions that need answering.”
The concept of “gene-drive” technology was first explored in 2003 but hit a roadblock when researchers discovered that their gene drives vanished after a few generations, due to mutations that prevented them from spreading.
But Hammond’s team identified a crucial sex determination gene — dubbed doublesex — that is identical among Anopheles gambiae mosquitoes, the insects behind most of the malaria transmission in sub-Saharan Africa.
In 2018, the scientists used the doublesex gene drive on about 600 Anopheles gambiae mosquitoes housed in a small cage — and within seven to 11 generations, no more of their offspring were produced, the Guardian reported.
Field trials were later launched in Burkina Faso by the Target Malaria research consortium, which includes the team from London. They released genetically modified, sterile, male mosquitoes to see whether they could survive and be tracked.
Now, in the latest study, Hammond and his team released relatively small numbers of the modified pests into much larger cages housing hundreds of wild mosquitoes, and that more closely resembled real-world conditions.
The cages were designed to encourage complex mating, resting, foraging and egg-laying behaviors that would be impossible in small cages, the Guardian said.
The team tracked how quickly the gene drive spread and studied its impact on female fertility.
“This is something that has never been achieved before — a single release of gene drive into a simulated field population, which brought about a crash of that entire population within a year, with no further human input. It is entirely self-sustaining,” Hammond said.
The expert stressed that more comprehensive testing and environmental risk assessments are necessary before larger field trials could take place.
Despite a reduction in malaria over the past few decades, there were still 229 million cases and 409,000 deaths in 2019, the Guardian reported.