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Archive for Friday, June 23, 2000

Genetic scientists bite back at mosquito

June 23, 2000

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Although a swift slap is the common defense against mosquitoes, scientists are now beginning to disarm the little zingers via genetic engineering.

The goal is to render mosquitoes immune to malaria and other diseases, ending their ability to transmit the disabling ailments to humans.

According to researchers working in England, Germany and Greece, they have succeeded in putting new genes into an important strain of mosquito, and then getting the genes to work properly.

"This is the first reliable system for germline transformation of a vector (carrier) of human malaria," Flaminia Catteruccia, Andrea Crisanti, Fotis Kafatos and four other researchers wrote Wednesday in the journal Nature. "We expect this technology to be successfully extended to the most important malarial vector, Anopheles gambiae."

Eventually, the idea is to make it impossible for malaria parasites to use mosquitoes as shipping and handling agents.

The research team experimented on the mosquito called Anopheles stephensi, a prominent carrier of malaria in Asia, especially India. The next step is to change the genes in another strain, A. gambiae, malaria's major vector in sub-Saharan Africa.

According to molecular geneticist Craig Coates "within the next five years a refractory (malaria-resistant) strain" of mosquitoes "will be produced," perhaps opening the door to malaria control.

At present, hundreds of millions of people in tropical areas are infected, and many of them die.

The malaria problem has worsened as mosquitoes became increasingly resistant to insecticides, and the blood-borne parasites have developed resistance to therapeutic drugs. As a result, medical science has been fighting a losing battle against the parasitic tropical disease.

According to Coates, similar experiments with genetic engineering have already succeeded with another important type of mosquito, the Aedes strains, which carry viral diseases such as yellow fever. But, Coates said, it is much harder to manipulate genes in the Anopheles mosquitoes, the carriers of malaria. "They are more difficult to work with," he said, "and we had not had the same success with genetic engineering."

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