KPLU Local News
(2009-07-21)
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A graduate student majoring in entomology holds her hand in a cage full of mosquitoes.
AP Image
It's that time of year, when you're probably finding ways to avoid mosquitoes. What if you lived in a country where all those mosquitoes were carrying the deadly malaria parasite? It's easy to see why a vaccine is needed. But, malaria has proven more complex than many other diseases.
Stefan Kappe of the Seattle Biomedical Research Institute is leading one team trying to solve the riddle. He's had success testing his vaccine in mice, and the next step is to test it in humans. Along with the usual safety issues, he'll need people to volunteer to get bitten by mosquitoes. Each volunteer will insert an arm into a cardboard box, with a net on top and 200 mosquitoes inside--then wait for them all to bite.
If that sounds, well, not so great, Kappe says not to worry. "It's well tolerated," he says, having tested it with disease-free mosquitoes.
All volunteers will be screened in advance for allergies to the bites. The first phases will be conducted at Walter Reed hospital in Washington, DC. He's personally tried it with 20 mosquitoes and is volunteering for the full 200. Why? To be part of history, he says, eliminating malaria.
In a paper published this week in The Proceedings of the National Academies of Science (PNAS), Kappe's research group shows how the vaccine works. It uses a live--but weakened--parasite to prime the immune system. There are two bits of genetic information needed by the parasite to survive once it gets inside a human liver. Without those genes, the parasite dies off before it can reproduce. In the meantime, your body's immune system has time to learn an immune response. Later, if the wild parasite shows up in your body, the immune system is already primed to kill it off.
Still, the vaccine has to prove safe and effective in humans, not just mice. Those trials should begin in early 2010. Then, they'll need a safe way to mass-produce it, while cultivating it inside mosquitoes' salivary glands. So far, that's the only way to grow the parasite.
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