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Mosquitos being tested to be vaccinators against malaria

Associated Press

Two British scientists are using genetically engineered mosquitoes as flying syringes to try to vaccinate people against malaria and other diseases. Professor Bob Sinden of the University of London's Imperial College and Professor Julian Crampton of Liverpool University's School of Tropical Medicine say they have taken a key step in the process but still have a long way to go. The two scientists received a patent last year, but their technique is only being publicized now following a
report by Derwent, a scientific information company.


"The key thing that we're doing is using the mosquito as the syringe," Sinden said in an interview Monday. "We are using malaria as an example." What the scientists are trying to do is similar to what was done in developing the polio vaccine: take bits of the parasite that causes malaria and put it into the body so the body builds up its own immunity. Malaria is transmitted to humans by the bite of an infected
mosquito. The scientists' idea is to use genetically engineered mosquitos that vaccinate the people they bite instead of giving them malaria. "In the world you have 400 million cases of malaria a year, and what we are looking to do is produce vaccines against this disease," Sinden said. "What numerous scientists are doing are looking for parasite proteins that are critically important for growth of the malaria, and then to immunize people with those proteins, and this will then incapacitate the malaria parasite," he said.

In their technique, a genetically engineered mosquito would transfer a protein through its saliva which would act as a vaccine to immunize a person against malaria. The trick is to modify the insect's salivary gland by introducing a parasite gene that produces an antigen known to stimulate the body to resist the malaria parasite, Sinden said. "We have successfully taken a malaria gene and put it into a mosquito salivary gland where the parasite protein is made and then used the salivary gland to immunize a mouse so that the mouse will not transmit malaria,"
he said. Crampton's team of researchers introduced the gene into isolated salivary glands from the mosquito, he said. What the scientists now have to do - "and this is a huge step" - is to carry out the experiment in a live mosquito instead of in a test tube so when it bites "it spits the parasite protein which will immunize you against malaria," Sinden said. "The big problem that we've got is that the technology for introducing genes into whole mosquitos is only just emerging, and until that step is completed, we are still talking of a theory," he said.

But the scientists are optimistic the technique will emerge in the near future. Potentially, the technique could be used to immunize people and animals against a wide range of diseases, and any biting insect could be used to carry the vaccine, not just mosquitoes, Sinden said. "We are extremely cautious about testing these mosquitoes in closed laboratory colonies, and we have no intention of releasing any genetically engineered insect without full and detailed technical and safety considerations," he said.

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