Biting Back

Originally posted Mar 2011

Genetically engineered fungi may eradicate malaria.

Scientists from University of Maryland, Johns Hopkins, and University of Westminster (UK) have done something very impressive. They’ve managed to develop a method which might make malaria a thing of the past, even in the developing world, using genetically-modified fungi that either kill the parasites responsible, or prevent them from entering the human bloodstream from mosquito bites.

Malaria is a particularly difficult problem for biologists, because of the nature of the organism responsible for it. Protists of the genus Plasmodium are the culprits, and as protists, they have features similar to those of animal cells. This makes it difficult to target them with drugs, and the parasites (there are 11 species of Plasmodium that cause human malaria) have evolved resistance to a number of drugs that had at one point proved effective.

The scientists’ plan, then, was to attack the mosquito that carries Plasmodium. They had heard that certain types of fungus acted as a sort of natural insecticide, and started from there. This fungus, Metarhizium anisopliae, doesn’t kill the mosquitoes until they are older, allowing them time to reproduce. This prevents them from building an evolutionary resistance to this new agent. The fungus was then modified in two ways: one change caused the mosquito salivary glands to be coated with a film, preventing the entry of Plasmodium into the glands (and hence its subsequent injection into humans), the second expressed a venom found in scorpions, which killed Plasmodium.

The fungus would likely be applied as a spray or a liquid to the mosquitoes’ habitat, or perhaps the humans’. Existing fungal agents intended to be used as insecticides are sold as suspensions of the fungal spores in water. It might also be possible to grow the fungus in the regions affected, increasing their ability to protect humans at even lower cost.

If this fungus could be made into an effective anti-malarial agent (and there’s little reason to believe it couldn’t), it would go a very long way toward freeing the developing world of the third most deadly single infectious disease. What’s more, it would show the biological community and the world that there are still giant advances to be made in disease control.

Today’s disease-fighting world is itching for good news. Cancer and AIDS are still raging, and even less-sophisticated diseases like tuberculosis are vexing, complicated by unpredictable patterns of human behavior. Assuming this cure will work in the world at large, and eradicates malaria as expected, the benefit to biology in general would likely be tremendous, if only to raise its spirits.

These scientists took a problem and presented a good possible solution that wasn’t simple, wasn’t obvious, and required knowledge of several sub-fields. They are perfect examples of what modern scientists should be: widely knowledgeable and able to draw on previous research without being constrained by it. Congratulations, researchers, and thank you.

For further information on the fungus and the research behind it, refer to this Wired / Ars Technica article.