Robust Mosquitoes, Less Malaria

By Jackie Powder

The mosquito’s immune system might be more sophisticated than anyone suspected. And that could help scientists to develop novel strategies to control malaria, a disease that annually kills more than 650,000 people worldwide.

Mosquitoes can’t produce antibodies like humans do to target specific infections with sniper-like precision. But, in a new study, Bloomberg School scientists have identified a single gene called AgDscam that makes it possible for the insects to destroy an array of pathogens—including the human malaria parasite, Plasmodium falciparum—with some degree of specificity. 

“When the mosquito is infected with the human malaria parasite, this gene will produce a certain repertoire of proteins that have the ability to bind to the parasite in the [mosquito’s] gut tissue and mediate its killing,” says George Dimopoulos, PhD, MBA, the study’s senior author. It was published in Cell Host & Microbe in October 2012.

“It’s exciting because insects have been known not to have antibodies and people wonder how they can deal with a broad spectrum of bacteria, parasites and viruses,” explains Dimopoulos, a Molecular Microbiology and Immunology professor. “The AgDscam gene does not produce antibodies but the building blocks of antibodies, and can also combine them to produce diversity in defense specificity.

“It’s like casting a net, rather than shooting a harpoon,” he adds, comparing the mosquito and human immune systems. Mosquitoes use the AgDscam gene to “weave the net,” researchers discovered. It contains immunoglobulin domains—present in human antibodies—that theoretically can produce up to 32,000 protein combinations to resist pathogens, including different malaria parasite species.

However, it’s unclear exactly how the AgDscam proteins kill the pathogens. “If we can understand this mechanism better at the molecular level,” says Dimopoulos, “we may be able to create a genetically modified mosquito that produces a repertoire of proteins capable of targeting a broader spectrum of malaria parasite strains, rather than just a single strain.”