London: For the first time, researchers led by the Imperial College London, have genetically modified malarial mosquitoes so that they carry a gene that disrupts egg production in female mosquitoes.
They used a technology called “gene drive” to ensure the gene for infertility is passed down at an accelerated rate to offspring — spreading the gene through a population over time and raising the possibility of reducing the spread of disease.
Within a few years, the spread could drastically reduce or eliminate local populations of the malaria-carrying mosquito species.
The mosquito species Anopheles gambiae is a major carrier of malaria parasites in sub-Saharan Africa, where 90 percent of annual malaria deaths occur.
Malaria infects over 200 million people each year and causes more than 430,000 deaths.
“Scientists have been trying to tackle malaria for more than 100 years. If successful, this technology has the potential to substantially reduce the transmission of malaria,” said study co-author professor Andrea Crisanti.
Normally, each gene variant has 50 percent chance of being passed down from parents to their offspring.
In the team’s experiments with Anopheles gambiae, the gene for infertility was transmitted to more than 90 percent of both male and female mosquitoes’ offspring.
The technique uses recessive genes so that many mosquitoes will inherit only one copy of the gene.
Two copies are needed to cause infertility, meaning that mosquitoes with only one copy are carriers, and can spread the gene through a population.
This is the first time the technique has been demonstrated in Anopheles gambiae.
The team targeted three different fertility genes and tested each for their suitability for affecting a mosquito population through gene drive, demonstrating the strength and flexibility of the technique to be applied to a range of genes.
“As with any new technology, it will be at least 10 more years before gene drive malaria mosquitoes could be a working intervention,” added professor Austin Burt from Imperial’s department of life sciences.
There are roughly 3,400 different species of mosquitoes worldwide.
“While Anopheles gambiae is an important carrier of malaria, it is only one of around 800 species of mosquito in Africa, so suppressing it in certain areas should not significantly impact the local ecosystem,” noted lead author Dr Tony Nolan.
The team aims to improve the expression of their gene drive elements. Exploring target genes is also helping the researchers to learn more about basic mosquito biology.
The results were published in the journal Nature Biotechnology.