Gene Switch Identified in Malaria-Vector Mosquitoes

Researchers have identified a gene called SPRN6 as a regulatory switch that is turned on in Anopheles mosquitoes when they are infected with the Plasmodium parasite.

This gene apparently helps the mosquito, the transmission vector for malaria in people, which is a leading cause of disease and death globally, killing a conservatively estimated million people among an estimated 300 million to 500 million cases a year, according to the World Health Organization.

Only Anopheles mosquitoes can transmit malaria. They transmit it only after having taken a previous blood meal from an infected person. Once inside the mosquito, the parasite matures in the gut and then travels to the salivary glands, where it can infect a human in the mosquitoes' next blood meal.

The protective gene was identified in a study conducted by a team of investigators from the Johns Hopkins Bloomberg School of Public Health Malaria Research Institute, the University of Texas Medical Branch, the Imperial College of London and the European Molecular Biology Laboratory in Germany. The study was published online in the journal Proceedings of the National Academy of Sciences

The researchers used RNA interference, a new molecular biology tool, to deactivate the gene and found that the parasite level in the genetically modified mosquitoes increased in the Anopheles stephensi and the ability of the Anopheles gambiae to rid itself of the parasite.

The researchers are using this knowledge to create a transgenic mosquito with the SPRN6 gene permanently on in an effort to create a mosquito immune to the parasite and thus a weapon to disrupt the transmission of the disease.

Malaria, a problem that affects 40 percent of the world's population, is not going away despite years of eradication efforts in the west, and the parasite is increasingly resistant to drugs, and the mosquito to insecticide. And, malaria may be expanding it reach from tropical areas because of global climate change.

Check out the article Fighting Malaria in Chemical and Engineering News and find the Oct. 24 issue of the New Yorker magazine for an informative article by Michael Specter [not available online].