A "malaria-proof" mosquito hasbeen created by scientists who have engineered a genetic "on" switchthat permanently activates a malaria-destroying response, according totheir report in the journal Public Library of Science Pathogens. If these mosquitoes are successfully introduced into the wild, theycould prevent millions of people from becoming infected withlife-threatening Plasmodium -- the parasite that causes malaria. "We were surprised how well this works," said Michael Riehle, aprofessor at the University of Arizona and a co-author of the new PLoS Pathogenspaper. "We were just hoping to see some effect on the mosquitoes'growth rate, lifespan or their susceptibility to the parasite. But itwas great to see that our construct blocked the infection processcompletely." An estimated 250 million people are infected by the four kinds of Plasmodium each year, but each infection comes from female Anopheles mosquitoes. While sucking blood to feed her brood, the mosquito ingests an average of 40 Plasmodium parasites. The parasites develop on the mosquitoes mid-gut, while the insect'simmune system does its best to thin the herd. A few parasites escapeand eventually migrate to the mosquito's salivary glands, where theysit, ready to infect the next unfortunate victim. The scientists focused on the parasites as they develop by targetingthe Akt gene. Previous studies have shown that Akt affects a mosquito'slongevity, immune system and digestion -- all of which could affect thebug's susceptibility to malaria. As a result, the team engineered a special version of the Akt gene into the eggs of Anopheles stephensi mosquitoes. After infecting the mosquitoes with Plasmodiumparasites and allowing them to develop, the scientists examined themosquitoes. They found no trace of the malaria parasites in mosquitoesthat had the amped up version of Akt. Exactly how Akt eliminates malaria in mosquitoes is unknown. Older mosquitoes are more likely to carry malaria than youngermosquitoes, and Akt mosquitoes die sooner. That suggests age might be afactor. The mosquito's immune system naturally destroys many malariaparasites so it stands to reason that a beefed up immune system coulddestroy all of the parasites. The mosquito's digestive system couldalso simply consume the parasites as it digests its blood meal. "What they've done is take a key point in the insulin signalingpathway, and expressed an active form of it in the gut," said MarkBrown, a doctor at the University of Georgia who is familiar with thenew research. Akt, said Brown, "could be activated at any step alongthat process." Regardless of how Akt works, it won't be working for any mosquitoes in the wild any time soon. "We are at least a decade away from actually releasing mosquitoes intothe wild," said Riehle. The engineered mosquitoes could mate with wildmosquitoes, but that the team still needs a more effective way to drivethe inserted genes through the entire population. Research labs across the world are trying to solve that exact problem, but so far no solution has been developed. View this link