BBC NEWS | Science/Nature | GM mosquito 'could fight malaria'

BBC NEWS | Science/Nature | GM mosquito 'could fight malaria'

Last Updated: Monday, 19 March 2007, 22:48 GMT

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GM mosquito 'could fight malaria'

The GM mosquitoes could be identified by their green fluorescent eyes


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A genetically-modified (GM) strain of malaria-resistant mosquito has been created that is better able to survive than disease-carrying insects.
It gives new impetus to one strategy for controlling the disease: introduce the GM insects into wild populations in the hope that they will take over.

The insect carries a gene that prevents infection by the malaria parasite.

Details of the work by a US team appear in Proceedings of the National Academy of Sciences journal.

In the laboratory, equal numbers of genetically modified and ordinary "wild-type" mosquitoes were allowed to feed on malaria-infected mice.

As they reproduced, more of the GM, or transgenic, mosquitoes survived. After nine generations, 70% of the insects belonged to the malaria-resistant strain.

The scientists also inserted the gene for green fluorescent protein (GFP) into the transgenic mosquitoes which made their eyes glow green.

This helped the researchers to easily count the transgenic and non-transgenic insects.

'Fitness advantage'

Dr Mauro Marrelli and his colleagues from Johns Hopkins University in Baltimore, Maryland, wrote in PNAS: "To our knowledge, no-one has previously reported a demonstration that transgenic mosquitoes can exhibit a fitness advantage over non-transgenics."

The modified mosquitoes had a higher survival rate and laid more eggs.

However, when both sets of insects were fed non-infected blood they competed equally well.

For resistant mosquitoes to be useful in the wild, they must survive better than non-resistant mosquitoes even when not exposed to malaria.

Even so, the researchers concluded: "The results have important implications for implementation of malaria control by means of genetic modification of mosquitoes."

GM mosquitoes that interfered with development of the malaria parasite would make it more difficult for the organism to become re-established after it had been eradicated from a target area, they said.

Malaria, spread by the single-celled parasite Plasmodium, is endemic in parts of Asia, Africa, and central and south America.

The organism is passed to humans through the bite of the Anopheles mosquito. Each year it makes 300 million people ill and causes a million deaths worldwide.

Some 90% of cases are in sub-Saharan Africa, where a child dies of malaria every 30 seconds