THURSDAY, Sept. 22, 2022 (HealthDay News) — The fight against malaria may depend on genetically engineered mosquitoes with so-called “gene drive.”

Researchers from the Transmission: Zero team at Imperial College London report that they have engineered mosquitoes that slow the growth of the malaria-causing parasites in their guts. This delay will mean that the mosquito will reach its natural lifespan before the parasite reaches the mosquito’s salivary glands. So the bite will not spread the disease.

In the laboratory, it dramatically reduced the spread of malaria.

“Since 2015 progress against malaria has stalled. Mosquitoes and the parasites they carry are becoming resistant to available interventions, such as insecticides and treatments, and funding has stopped. We need to develop new, innovative tools,” study co-author Tibebu Habtevold, who is a researcher in the college’s Department of Biological Sciences, said in a college news release.

Last year, malaria infected 241 million people and killed 627,000 of them, mostly children under the age of 5 in sub-Saharan Africa.

Malaria is spread when a female mosquito bites an infected person. The parasite then develops in the mosquito’s gut, moves into its salivary glands, and can spread to the next person bitten by the mosquito.

According to research, about 10% of mosquitoes live long enough for the parasite to become contagious. Genetic engineering would delay this development.

The researchers achieved this by getting mosquitoes to produce two molecules called antimicrobial peptides in their guts after they ate a blood meal. The peptides impair the development of the malaria parasite for several days.

It also results in a shortened lifespan of mosquitoes.

“For many years, we have tried without success to create mosquitoes that cannot be infected with parasites, or ones that can clear all parasites with their immune system. Delaying the development of the parasite inside the mosquito is a conceptual shift that has opened up a much greater possibility of blocking malaria transmission from mosquitoes to humans,” said co-author Astrid Hoermann, also from the Department of Life Sciences.

The researchers had to use a genetic trick called gene drive to ensure that the lab-bred modification could spread to wild mosquitoes. While conventional inbreeding would do some of this work, the shorter lifespan of genetically modified mosquitoes would mean that their type would be wiped out.

The researchers noted that adding the gene drive to mosquitoes allows the modification to be preferentially inherited, so it can spread more quickly in wild mosquito populations.

It is critical that the team minimizes any risk through careful planning and laboratory testing before moving forward. To do this, the team uses two separate but compatible strains of modified mosquitoes. One will have an anti-parasite modification and the other will have a gene drive.

This would allow the researchers to first test the modification against the parasites and then add the gene drive if preliminary tests are effective.

Collaborators at the Institute for Disease Modeling at the Bill & Melinda Gates Foundation have also found that these modifications can be a powerful tool.

The team made changes to the Anopheles gambiaethe main vector of malaria is a species of mosquito in sub-Saharan Africa.

The work was funded by the Bill and Melinda Gates Foundation. The findings were published on September 22 in the journal Achievements of science.

Additional information

The US Centers for Disease Control and Prevention has more malaria.

SOURCE: Imperial College London, news release, 22 September 2022

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