by Martin Enserink on March 18, 2010 8:00 PM |
Here's a study to file under "unworkable but very cool." A group of Japanese researchers has developed a mosquito that spreads vaccine instead of disease. Even the researchers admit, however, that regulatory and ethical problems will prevent the critters from ever taking wing—at least for the delivery of human vaccines.
Scientists have dreamed up various ways to tinker with insects' DNA to fight disease. One option is to create strains of mosquitoes that are resistant to infections with parasites or viruses, or that are unable to pass the pathogens on to humans. These would somehow have to replace the natural, disease-bearing mosquitoes, which is a tall order. Another strategy closer to becoming reality is to release transgenic mosquitoes that, when they mate with wild-type counterparts, don't produce viable offspring. That would shrink the population over time.
The new study relies on a very different mechanism: Use mosquitoes to become what the scientists call "flying vaccinators." Normally, when mosquitoes bite, they inject a tiny drop of saliva that prevents the host's blood from clotting. The Japanese group decided to add an antigen-a compound that triggers an immune response-to the mix of proteins in the insect's saliva.
A group by led by molecular geneticist Shigeto Yoshida of Jichi Medical University in Tochigi, Japan, identified a region in the genome of Anopheles stephensi-a malaria mosquito-called a promoter that turns on genes only in the insects' saliva. To this promoter they attached SP15, a candidate vaccine against leishmaniasis, a parasitic disease spread by sand flies that can cause skin sores and organ damage. Sure enough, the mosquitoes produced SP15 in their saliva, the team reports in the current issue of Insect Molecular Biology. And when the insects were allowed to feast on mice, the mice developed antibodies against SP15.
http://news.sciencemag.org/sciencenow/2010/03/researchers-turn-mosquitoes-into.html
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