JOHNS HOPKINS (US) — Mosquito immune systems can be engineered to more effectively kill malaria-carrying parasites, blocking transmission to humans.
Researchers from Johns Hopkins University report that the genetic modification does not compromise the mosquitoes physically. That makes it more likely that they would be able to compete in the wild and spread the genetic change to normal insect populations.
“Malaria is one of world’s most serious public health problems,” says George Dimopoulos, senior author of the study. “New control methods are urgently needed.
“We’ve taken a giant step towards the development of new mosquito strains that could be released to limit malaria transmission, but further studies are needed to render this approach safe and fail-proof.”
Worldwide, malaria afflicts more than 225 million people. Each year, the disease kills approximately 800,000, many of them children living in Africa.
Mosquitoes and the malaria parasite are becoming more resistant to insecticides and drugs, says Dimopoulos, associate professor of molecular microbiology and immunology.
“The immune system of the [normal] Anopheles mosquito is capable of killing a large proportion—but not all—of the disease-causing parasites that are ingested when the mosquito feeds on an infected human,” he says.
“We’ve genetically engineered this immune system to create mosquitoes that are better at blocking the transmission of the human malaria parasite Plasmodium falciparum.”
In the study, published in the journal PLoS Pathogens, researchers report they genetically engineered Anopheles mosquitoes to produce higher than normal levels of the immune system protein Rel2 when they feed on blood. Rel2 acts against the malaria parasite in the mosquito by launching an immune attack involving a variety of anti-parasitic molecules.
This approach essentially uses one of the insect’s own genes to strengthen its parasite-killing capabilities, as opposed to introducing a new gene into mosquito DNA.
After further development, the researchers’ hope is to introduce engineered mosquitoes into the wild to breed with normal insects and convert malaria-transmitting populations to Plasmodium-resistant ones.
One possible obstacle is the fitness of the genetically modified mosquitoes, since they would have to compete with the natural malaria-transmitting mosquitoes.
The Johns Hopkins research showed that the Rel2 genetically modified mosquito strain lived as long, and laid as many eggs, as the non-modified “wild-type” mosquitoes. That suggests that their fitness had not become significantly impaired, the researchers say.
The National Institutes of Health and the Johns Hopkins Malaria Research Institute provided funding for the research.
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