The scientists tested this approach on Anopheles gambiae mosquitoes, endemic to Tanzania, where they carry malaria.
James Ghatani/CDC via AP/Alamy
Genetic technology known as gene drive may help prevent malaria by spreading genes to wild mosquitoes that stop transmission of the parasite. Tests in a laboratory in Tanzania have now confirmed that one potential gene drive should achieve this if it were to be released in the country.
“It will be a revolutionary technology, that’s for sure,” says George Christofides at Imperial College London.
A particular piece of DNA in an animal's genome is usually passed on to only half of its offspring because the parental DNA is split in half between the egg and sperm. A gene drive increases this fraction, meaning that a little DNA can quickly spread through a population even if it does not provide any evolutionary benefit.
There are many naturally occurring gene drives that act through a variety of mechanisms—possibly even in some human populations – and in 2013 biologists developed artificial gene drives using CRISPR gene editing technology, which works by copying pieces of DNA from one chromosome to another.
The idea is to use these engines to propagate DNA fragments. that block the transmission of malaria – but what bits? Christofides reported in 2022 that the development of malaria parasites inside mosquitoes can be significantly reduced by two tiny proteinsone is derived from honeybees and the other from the African clawed frog. The added genes for these anti-malarial proteins may be linked to a gene for an enzyme that helps mosquitoes digest blood, so anti-malarial proteins are produced after the mosquito eats and secreted into its gut.
But these tests were carried out using laboratory strains mosquitoes and malaria parasites collected decades ago, so it was unclear whether this approach would work in Africa today.
Now researchers, including Christofides and Dixon Lvetoyer at the Ifakara Institute of Health in Tanzania changed local Anopheles gambian mosquitoes to produce gene drive components based on this approach. The components were kept separately, meaning the gene drive could not spread, and the mosquitoes were kept in a secure facility.
Tests show reliable suppression of malaria parasites taken from infected children, as well as effective copying of genes for anti-malarial proteins. “We can now say that this technology can work in the field,” says Christofides.
The next step will be to release mosquitoes that produce anti-malarial proteins onto an island in Lake Victoria to see how they behave in the wild. The team is engaging with local communities and also conducting risk assessments, Lvetoyer said. “To date, political and public support remains positive.”
It is hoped that the gene drive will help eradicate malaria in areas where A. gambia “This is the only species that spreads malaria,” says Christofides. “Gene drives could turn the tide,” he says.
Several other groups are also working on gene drives to combat malaria. control of various pests.
Genetically modified mosquitoes are already appearing. released to control wild mosquito populations in some countries, but these approaches rely on the constant release of very large numbers of insects.
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