Entomologists have for the first time managed to genetically alter mosquitoes in a way that renders them completely immune to malaria.
The development raises hopes that malaria-proof mosquitoes with a genetic edge over the normal type could be released into the wild to interbreed with and eventually replace them.
While malaria-resistant varieties have been successfuly bred in the past, this is the first time that a completely immune mosquito has been created.
“If you want to effectively stop the spreading of the malaria parasite, you need mosquitoes that are no less than 100 percent resistant to it,” says team leader Michael Riehle of the University of Arizona.
“If a single parasite slips through and infects a human, the whole approach will be doomed to fail.”
Riehle’s team used molecular biology techniques to design a piece of genetic information that could insert itself into a mosquito’s genome. This was then injected into the eggs of the mosquitoes. The emerging generation carried the altered genetic information and passed it on to future generations.
For their experiments, the scientists used Anopheles Stephensi, a mosquito species that’s a major malaria vector throughout the Indian subcontinent.
When Riehle and his co-workers studied the genetically modified mosquitoes after feeding them malaria-infested blood, they found that the Plasmodium parasites did not infect a single study animal.
“We were surprised how well this works,” said Riehle. “We were just hoping to see some effect on the mosquitoes’ growth rate, lifespan or their susceptibility to the parasite, but it was great to see that our construct blocked the infection process completely.”
Of the estimated 250 million people who contract malaria each year, one million – mostly children – die. Ninety percent of deaths occur in sub-Saharan Africa.