Published On: Fri, Nov 27th, 2015

Genetically modified mosquitoes can’t spread malaria, scientists say

imrsScientists in California say they have genetically modified a strain of mosquitoes that cannot be infected by the malaria parasite and cannot spread it to humans.

Using a technique known as gene editing, the American researchers have inserted new DNA into the mosquitoes’ genes that will prevent malarial transmission, they report.

The researchers have performed the technique on Anopheles stephensi mosquitoes, which are leading malaria vectors in Asia, but say that their findings offer hope that the same method could also work in other mosquito species.

The genetically engineered mosquitoes will not only be unable to transmit malaria, but the pathogen-resistant trait will spread quickly in a population of the insects, with 99.5 percent of successive generations carrying the new genes, according to the scientists.

That opens up the possibility that the technique can go a long way toward eliminating the disease that threatens about 3.2 billion people – almost half of the world’s population.

Malaria struck almost 200 million people in 2013 alone, killing nearly a half million, said study leader Anthony James at the University of California, Irvine.

“We know the gene works,” he stated. “The mosquitoes we created are not the final brand, but we know this technology allows us to efficiently create large populations.”

James and his team at Irvine worked with colleagues at the University of California, San Diego, to develop a technique to insert an engineered anti-malarial mutation into both copies of a particular gene in the insects, making it more likely to be passed along to subsequent generations.

They used a genetic engineering technique known as Crispr, which allows scientists to cut or snip DNA at a particular location in the genome and insert desired new or mutated genes in that spot.

The modified genes inserted into the mosquitoes bind with the malaria parasites, keeping them from recognizing its insect host and moving about in the mosquito’s body.

“You can think of it as [being] blinded,” James said. “As a result, the parasite cannot move into the insect’s salivary gland, where transmission takes place when a mosquito bites a human.

“This represents a significant first step.”

Professor David Conway, an expert from the London School of Hygiene & Tropical Medicine, who was not directly connected with the new research, told BBC News: “It’s not the finished product yet but it certainly looks promising. It does look like the genetic editing works.”

Other scientists have been looking at genetically modifying mosquitoes to render them infertile, so that they die out. But some experts fear that eliminating mosquitoes entirely may have unforeseen and unwanted consequences. Replacing disease-carrying mosquitoes with harmless breeds is a potential alternative.

The California study appeared in the Proceedings of the National Academy of Sciences (PNAS) journal.

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