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Last Updated: Friday, 26 March, 2004, 00:00 GMT
Mosquito immunity clue to malaria
Mosquitoes carry malaria
Scientists believe it may be possible to modify a mosquito's immune response to block the transmission of malaria to humans.

They have identified four proteins produced by the insect - two kill the malaria parasite, and two protect it.

They believe the proteins could be altered to wipe out the parasite so it cannot be passed on to humans.

The research, in the journals Cell and Science, was carried out by the European Molecular Biology Laboratory.

These studies give us some very real options for fighting the disease in the insect before it even has a chance to be passed to a human.
Professor Fotis Kafatos
The research, undertaken by two separate teams at the German lab, focused on a mosquito called Anopheles gambie, which is responsible for the transmission of most malaria cases in Africa.

The first study identified two proteins, CTL4 and CTLMA2, which appear to protect the malaria parasite, Plasmodium, as it develops in the mosquito.

When the genes that make them were inactivated, mosquitoes destroyed 97% of malaria parasites developing in their bodies.

Opposite effect

The second study identified two other mosquito proteins, which appear to have the opposite effect.

The proteins, TEP1 and LRIM, are able to kill off the malaria parasite - but they seem to vary in how well they work.

This might explain why some mosquitoes pass malaria on to humans when they bite, and others do not.

The researchers believe it may be possible to boost the proteins' power to ensure they are able to kill off all traces of the parasite.

Professor Fotis Kafatos, director general of the EMBL, said: "Many researchers focus on the direct effects of Plasmodium on the human body but the mosquito is an equally important battleground in fighting the disease.

"These studies are the first to show the power of the mosquito's immune system and give us some very real options for fighting the disease in the insect before it even has a chance to be passed to a human."

The malaria parasite is picked up by a mosquito when it bites an infected organism. It develops in the insect's gut for three weeks before moving to the salivary glands ready to be passed on when the insect next feeds.

Transgenic insects

Dr Mike Osta, who collaborated on the research, told BBC News Online that further tests were required to determine whether it was feasible to breed genetically modified mosquitoes.

Potentially, it should be possible to release them into the wild at a later date and hope that they spread their genes through the natural population.

"Malaria is a complex interaction between man, mosquito and parasite which is evolving all the time," he said.

"We need to open up as many fronts as possible against the disease, and potentially this could complement developments in drugs and vaccines."

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