Scientists engineer mosquito strain with malaria-blocking genes

Scientists aiming to take thebite out of malaria have produced a strain of mosquitoescarrying genes that block its transmission, with the idea thatthey could breed with other members of their species in the wildand produce offspring that cannot spread the disease.

The researchers said on Monday they used gene-editing, agenetic engineering technique in which DNA can be inserted,replaced or deleted from a genome, on a species called Anophelesstephensi that spreads malaria in urban India.

They inserted DNA into the germ line, cells that pass ongenes from generation to generation, of the species, creating
mosquitoes with genes that prevent malaria transmission byproducing malaria-blocking antibodies. The genesare passed on to 99.5per cent of offspring.

Malaria is caused by parasites transmitted to people through the bites of infected female mosquitoes. The goal is to releasegenetically modified mosquitoes to mate with wild mosquitoes sothat their malaria-blocking genes enter the gene pool andeventually 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 per cent to more than 99 per cent in 10
generations, or about one season for mosquitoes," University ofCalifornia-San Diego biologist Valentino Gantz said.

University of California-San Diego biologist Ethan Biercalled this a "potent tool in sustainable control of malaria,"
as all the mosquitoes in a given region would carryanti-malarial genes.

Won't eradicate malaria

"We do not propose that this strategy alone will eradicatemalaria," 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 insustaining the elimination of malaria, James said.

Other scientists also have been working to creategenetically engineered mosquitoes. One group last year said itcreated a strain carrying a gene leading nearly all offspring tobe male, which could cause wild populations to plummet.

"In contrast, our much more flexible system only preventsmosquitoes from carrying malaria but can be used to do no harmto the mosquito. So it should generate the least amount ofecological damage," Bier said.

The UNWorld Health Organization estimates there will be214 million cases of malaria worldwide in 2015 and 438,000
deaths, most in sub-Saharan Africa.

The research was published in the Proceedings of theNational Academy of Sciences.