Modified Mosquitoes May Be Anti-Malaria Allies

With World Malaria Day (April 25) around the corner, new discoveries suggest our greatest allies in the fight against malaria may be the mosquitoes themselves

Although saddled with a lousy public image, mosquitoes have immune systems that actually kill 80 to 90 percent of the malaria parasites that enter the insect's bodies, a new study says.

The discovery is part of an international effort to create a new generation of malaria treatments.

Genetically modified, malaria-fighting mosquitoes or even antibodies injected into humans and "fed" back to mosquitoes could someday be more effective at slowing the disease than today's simple mosquito nets, researchers say.

A mosquito-up approach to malaria control is feasible in the long term, researchers say. There are a couple of ways it could work.

In one scenario, scientists could create genetically modified mosquitoes, granting their immune systems pumped-up malaria-killing abilities.

The key would be to find a genetic drive mechanism—some factor that would give the new, malaria-fighting genes a selective advantage and help them spread quickly through wild mosquito populations via breeding, said Gregory Lanzaro, director of the Vector Genetics Lab at the University of California, Davis.

No one has figured this out for mosquitoes yet. But the U.S. Centers for Disease Control and Prevention is already testing a similar concept in blood-sucking assassin bugs as a way to stop the spread of deadly, difficult-to-cure Chagas disease, Lanzaro said.

The other option would be to develop antibodies that can fight the parasites' early, mosquito-dwelling forms—and "feed" the antibodies to the insects via human blood.

Mosquito immune systems don't produce antibodies on their own. And by the time the parasites reach humans, they have matured and found ways to hide out from human antibodies, said Marcelo Jacobs-Lorena, professor of molecular microbiology and immunology at the Johns Hopkins Malaria Research Institute in Baltimore.

But if we vaccinate humans with antibodies that target mosquito-stage malaria, those antibodies could be passed on to the mosquitoes when they feed on treated human blood, Jacobs-Lorena said.

Combined with a second, protective vaccine, this could be a real possibility, he said.

"There's a partially effective vaccine that protects humans that's being tested," Jacobs-Lorena said. "Neither it, nor the transmission-blocking vaccine would be 100 percent effective, but the combination may work."