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Researchers create malaria-proof mosquito
Researchers create malaria-proof mosquito
In the fight against malaria, scientists have genetically engineered a mosquito impervious to the disease.
Giving new hope toward eradicating malaria, scientists from the University of Arizona and the University of California–Davis have genetically modified a mosquito that cannot carry or transmit the parasite responsible for the disease.
Caused by the single-cell organism Plasmodium, the World Health Organization reports that malaria was responsible for nearly one million deaths in 2008. In this study, the research team focused on the genetics of Anopheles stephensi. The most common malaria vector in India, parts of Asia and the Middle East, A. stephensi carries Plasmodium vivax and Plasmodium ovale, two of four malaria strains. Current preventative measures include the use of the insect repellant DEET and anti-malarial drugs mefloquine and doxycyline, which have numerous side effects and have been shown to have diminishing effectiveness.
Researchers for this study looked at the insulin/insulin-like growth factor 1 signaling (IIS) cascade, which involves the key signaling protein Akt, and is integral in regulating the lifespan of a variety of organisms. Past research in the nematode Caenorhabditis elegans has shown that IIS cascade disruption led to the extension of its life span and a better resistance to bacterial infection.
Insulin signaling regulates a number of physiological processes that are important for disease transmission, including lifespan, reproduction and innate immunity. We decided to increase insulin signaling in the tissue where the malaria parasite is found for the longest period of time, the midgut.
In a transgenic line of A. stephensi, the team introduced the myr-AsteAkt-HA transcript, which encoded for the overexpression of the signaling molecule Akt in the midgut of mosquitoes. This increased Akt led to a 60–99% reduction in infection in insects heterozygous for the transcript, and a complete block of infection in homozygous insects. Furthermore, transgenic mosquitoes exhibited an 18–20% decrease in lifespan. Though the results indicate the multi-tiered impact of Akt on the spread of Plasmodium, the exact mechanisms at work are still elusive. The researchers’ next step is to figure out exactly how Akt works to increase innate immunity and decrease lifespan.
Riehle’s hope is to eventually replace all wild mosquitoes with these genetically modified ones in order to eliminate malaria completely, though that is still far off. “You would need to use a genetic drive system to ensure that [the transcript] is inherited by all of the progeny instead of the usual 50%,” Riehle said. “Hopefully there would be no long-term repercussions, but this would be thoroughly tested under controlled conditions before any field release would be considered. Because of all of this, we are at least a decade away from considering any field releases.”
One of the appeals of the research is its cost-effectiveness, said Riehle. While there is a larger upfront cost, he sees this strategy as self-sustaining with no maintenance required. “This approach will be a new tool in our toolbox to help control malaria,” he said.
The paper, “Activation of Akt signaling reduces the prevalence and intensity of malaria parasite infection and lifespan in Anopheles stephensi mosquitoes,” was published in PLoS Pathogens on July 15.
From:
http://www.biotechniques.com/news/Researchers-create-malaria-proof-mosquito/biotechniques-300252.html
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