Last year, Prof. Anthony James announced that he and his colleagues had genetically altered Aedes aegypti mosquitoes in a fashion that could drastically reduce their populations. In a nutshell, the altered genes cause the female mosquitoes to be born without wings – this makes it rather difficult for them to go foraging for blood, and turns them into easy prey for almost any predator. The non-biting males are born with wings, and subsequently go off and mate with unmodified females, passing the modified genes along to their offspring. Now, James has done some more genetic engineering, to create mosquitoes that can’t spread malaria.
The University of California, Irvine molecular biologist worked with colleagues from both UC Irvine, and the Pasteur Institute in Paris.
They started with mice that were infected with the Plasmodium falciparum parasite, which causes malaria. Those mice created antibodies in order to kill the parasites. The scientists identified the molecular components of this immune response, then altered the genes of the Anopheles stephensi mosquito in order to cause the same response to occur in their bodies – ordinarily, mosquitoes simply act as carriers of the parasites, exhibiting no immune response towards them.
In short, parasites picked up by the mosquitoes are killed by the insects’ altered immune systems, meaning that people subsequently bitten by those mosquitoes won’t develop malaria. Although the study was done using Anopheles stephensi, the technique could reportedly be used on dozens of different types of mosquitoes.
Unlike James’ previous efforts involving the flightless females, this approach would not actually reduce the numbers of mosquitoes present in an area. Much as many people might like the idea of the eradication of mosquitoes, this could be a good thing – it’s still unclear how the sudden elimination of a species as plentiful as the mosquito might affect ecosystems. That said, of course, the wisdom of releasing genetically modified mosquitoes to breed with wild populations might also be questioned.
Given that approximately one million people die worldwide every year from malaria – which is spread mostly by mosquitoes – it’s a risk that some people may be willing to take. “We see a complete deletion of the infectious version of the malaria parasite,” said James. “This blocking process within the insect that carries malaria can help significantly reduce human sickness and death.”
A paper on his research was published this week in the journal Proceedings of the National Academy of Sciences.
Source: University of California, Irvine
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