Scientists have genetically modified malaria-causing mosquitoes to become infertile and pass on the trait. (Representational Image)
Scientists have genetically modified malaria-causing mosquitoes to become infertile and pass on the trait rapidly, an advance that may substantially reduce the transmission of the deadly disease.
The mosquito species Anopheles gambiae is a major carrier of dangerous malaria parasites in sub-Saharan Africa, where 90 per cent of annual malaria deaths occur. Malaria infects more than 200 million people each year and causes more than 430,000 deaths, researchers said.
Now, a team of researchers led by Imperial College London have genetically modified Anopheles gambiae so that they carry a modified gene disrupting egg production in female mosquitoes.
They used a technology called 'gene drive' to ensure the gene is passed down at an accelerated rate to offspring, spreading the gene through a population over time. Within a few years, the spread could drastically reduce or eliminate local populations of the malaria-carrying mosquito species, researchers said.
The findings represent an important step forward in the ability to develop novel methods of vector control.
Normally, each gene variant has a 50 per cent chance of being passed down from parents to their offspring. In the new experiments with Anopheles gambiae, the gene for infertility was transmitted to more than 90 per cent 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.
"If successful, this technology has the potential to substantially reduce the transmission of malaria," said co-author Andrea Crisanti from the Department of Life Sciences at Imperial.
"It will be at least 10 more years before gene drive malaria mosquitoes could be a working intervention," said Professor Austin Burt from Imperial's Department of Life Sciences.
To test the gene drive, the team first identified three genes that impacted female fertility by disrupting the activity of suspected target genes.
They then modified the genes with the CRISPR/Cas9 endonuclease, a type of DNA cutting tool that can be designed to target very specific parts of the genetic code. The research was published in the journal Nature Biotechnology.