WASHINGTON—
Scientists aiming to take the bite out of malaria have
produced a strain of mosquitoes carrying genes that block its transmission,
with the idea that they could breed with other members of their species in the
wild and produce offspring that cannot spread the disease. The researchers said on Monday they used gene-editing, a
genetic engineering technique in which DNA can be inserted, replaced or deleted
from a genome, on a species called Anopheles stephensi that spreads malaria in India.
They inserted DNA into the germ line, cells that pass on
genes from generation to generation, of the species, creating mosquitoes with
genes that prevent malaria transmission by producing malaria-blocking
antibodies that are passed on to 99.5 percent of offspring. Malaria is caused by parasites transmitted to people through
the bites of infected female mosquitoes. The goal is to release genetically
modified mosquitoes to mate with wild mosquitoes so that their malaria-blocking
genes enter the gene pool and eventually overrun the population,
short-circuiting the species' ability to infect people with the parasites.
"It can spread through a population with great
efficiency, increasing from 1 percent to more than 99 percent in 10
generations, or about one season for mosquitoes," University of
California-San Diego biologist Valentino Gantz said.
University of California-San Diego biologist Ethan Bier
called this a "potent tool in sustainable control of malaria," as all
the mosquitoes in a given region would carry anti-malarial genes.
"We do not propose that this strategy alone will
eradicate malaria," University of California-Irvine molecular biologist
Anthony James said.
But in conjunction with treatment and preventive drugs,
future vaccines, mosquito-blocking bed nets and eradication of
mosquito-breeding sites, it could play a major role in sustaining the
elimination of malaria, James said. Other scientists also have been working to create
genetically engineered mosquitoes. One group last year said it created a strain
carrying a gene leading nearly all offspring to be male, which could cause wild
populations to plummet.
"In contrast, our much more flexible system only
prevents mosquitoes from carrying malaria but can be used to do no harm to the
mosquito. So it should generate the least amount of ecological damage,"
Bier said.
The U.N. World Health Organization estimates there will be
214 million cases of malaria worldwide in 2015 and 438,000 deaths, most in
sub-Saharan Africa.
The research was published in the Proceedings of the National Academy of Sciences.
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