Monday, July 16, 2012
Malaria parasite killed by gene-modified germs in study
By Kristen Hallam
July 16, 2012
Benign bacteria residing in mosquitoes’ guts can be recruited to destroy the parasite that causes malaria, offering a potential way to prevent infections, according to U.S. researchers.
Genetically modifying the germ enabled it to produce proteins toxic to the parasite without harming the insects, scientists from the Johns Hopkins Bloomberg School of Public Health in Baltimore and Duquesne University in Pittsburgh wrote today in the Proceedings of the National Academy of Sciences journal. The proportion of mosquitoes carrying the parasite fell by as much as 84 percent, the researchers said.
Malaria kills a child in Africa every minute, and about half the world’s population is at risk of infection, according to the Geneva-based World Health Organization. New ways of stopping the disease are needed as genetic mutations in parasites make them resistant to medicines, and as mosquitoes become less vulnerable to insecticides, the researchers said.
”These findings provide the foundation for the use of genetically modified symbiotic bacteria as a powerful tool to combat malaria,” the study’s authors wrote.
Mosquitoes transmit the Plasmodium parasite that causes malaria, whose symptoms include fever, headache, chills and vomiting. The parasite undergoes the most vulnerable part of its life cycle in the mosquito’s gut. The gut is also home to a bacterium, known as Pantoea agglomerans, which provides nutrients and helps its host cope with environmental changes.
The researchers administered genetically engineered bacteria to mosquitoes using cotton pads soaked with the germs suspended in a sugar solution. Thirty-two hours later, the insects were fed a meal of Plasmodium-infected blood. The modified bacteria were 98 percent effective in reducing the parasite’s development, and the repression of the parasites lasted for at least four days, according to the study.
More research is needed before trying the approach outside the lab, the study’s authors said.
Novartis AG of Basel, Switzerland, is among the companies working on new malaria treatments, though they’re not expected to be available for years. GlaxoSmithKline Plc is developing a product that would be the first malaria vaccine if approved. The shot, known as RTS,S, safely reduced illness in African infants by more than half in a study, the London-based company said in October.
Scientists also have been working on ways to genetically modify mosquitoes so that they die before they can transmit diseases such as malaria and dengue, also known as ”break-bone fever” because it’s so painful.
”Genetic modification of bacteria is a simpler approach,” said Marcelo Jacobs-Lorena, the lead author of the study and a professor at Johns Hopkins. ”The ultimate goal is to completely prevent the mosquito from spreading the malaria parasite to people.”
The research published today was funded by the U.S. National Institutes of Health, the Bill and Melinda Gates Foundation, the Johns Hopkins Malaria Research Institute and the Bloomberg Family Foundation.
The Johns Hopkins Bloomberg School of Public Health is named for Michael Bloomberg, New York City’s mayor and the founder and majority owner of Bloomberg News parent Bloomberg LP. The Bloomberg Family Foundation is the mayor’s charitable organization.