Mosquito bacteria made to fight malaria parasites

In the battle against malaria, doctors may one day have a microscopic ally. New research suggests that genetically modifying a bacterium commonly found in the gut of mosquitoes that harbor the malaria-causing parasite can make the mosquitos less likely to carry the disease. And if scientists can find a way to spread these bacteria in the wild, they could help end malaria’s deadly reign in the tropics.

Malaria kills approximately one million people every year, mostly African children under the age of 5.

Molecular biologist Marcelo Jacobs-Lorena, said, “It’s a very serious problem. It’s one of the three deadliest infectious diseases.”

And, he said, it’s one that is very hard to control.

“We have just drugs that kill the parasite in humans, and we have insecticides that kill the mosquito vector. And the parasite rather quickly acquires resistance to drugs, and the mosquitoes are acquiring resistance to insecticides. So the situation doesn’t get better,” he said.

Jacobs-Lorena is part of a team at Johns Hopkins and Duquesne Universities that is exploring an entirely new way to fight malaria. He says the key to success is choosing the right battleground. In this case, that battleground is inside the mosquito.

“Typically a mosquito ingests a couple thousand parasites. Then the parasite changes into a form called “ookinetes” that has to cross the midgut. Of the couple of thousand parasites that were ingested, only a few — about five or so — reach that stage where they cross the midgut. As you see, there’s a very strong bottleneck of parasite numbers in the midgut. That’s why it’s such a good target,” he said.

To take aim at the malaria parasites, Jacobs-Lorena and his colleagues gave weapons of a sort to bacteria that often live in a mosquito’s digestive system.

“So what we did is genetically engineer the bacteria to produce several antimalarial compounds,. . . . ,” he said.

When the newly-armed bacteria reached the mosquitoes’ midguts, they thrived. And Jacobs-Lorena says that they excelled in their new role as anti-parasite fighters. “In the laboratory, it works extremely well. Up to 98 percent of the parasites killed. So it is quite efficient,” he said.

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