Gene-based controls ‘could stop mosquitoes spreading malaria’

April 21st, 2011 - 11:19 am ICT by ANI  

London, April 21 (ANI): Scientists around the world are keenly seeking novel strategies to tackle malaria.

Now, scientists at Imperial College London and the University of Washington, Seattle, have developed gene-based control measures for mosquitoes that transmit malaria.

They have demonstrated how some genetic changes can be introduced into large laboratory mosquito populations over the span of a few generations by just a small number of modified mosquitoes.

In the future, this technological breakthrough could help to introduce a genetic change into a mosquito population and prevent it from transmitting the deadly malaria parasite, Plasmodium, to humans.

The researchers bred mosquitoes with a green fluorescent gene, as a marker that can easily be observed in experiments.

They allowed these insects to mingle and mate with a small number of mosquitoes that carried a segment of DNA coding for an enzyme capable of permanently inactivating the fluorescent gene.

After each generation, they counted how many mosquitoes still retained an active fluorescent gene.

They found that in experiments, which began with close to 99 percent of green fluorescent mosquitoes, more than half had lost their green marker genes in just 12 generations.

The study is the first successful proof-of-principle experiment of its kind, and suggests that this technique could similarly be used to propagate a genetic change within a wild mosquito population.

“This is an exciting technological development, one which I hope will pave the way for solutions to many global health problems. It demonstrates significant potential to control these disease-carrying mosquitoes. We expect to conduct many more experiments to determine its safety and reliability,” said Prof Andrea Crisanti, from the Department of Life Sciences at Imperial College London, a senior author of the study and head of the research group.

In the new experiments, the researchers inserted a unique segment of DNA producing a homing endonuclease enzyme into the mosquito Anopheles gambiae, one of the main carriers of malaria.

Homing endonucleases are found widely in nature, in organisms such as fungi.

The particular DNA element used in the study not only produces the enzyme that inactivates the green fluorescent gene but at the same time also inserts a copy of itself in the place of the inactivated gene.

This occurs in the mosquitoes’ sperm cells, so that when the insects mate almost all the offspring receive the DNA that produces the enzyme. In this way the DNA element can spread through the population over successive generations.

With this technology, the release of a small number of modified mosquitoes could eventually result in dramatic reduction of numbers of malaria-carrying mosquitoes over wide areas in countries where the deadly disease is currently endemic.

This could provide a low cost, safe, and highly effective public health tool for malaria eradication.

The study is published in Nature. (ANI)

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