Fighting Malaria with Mosquitoes

Image: CDC Public Health Image Library

Anopheles mosquitoes transmit malarial sporozoites while obtaining a blood meal.

Flu season is here. And while our human immune systems battle the winter onslaught of sniffle-causing viruses, another immune system on the opposite side of the globe is fighting the good fight. Its opponent: malaria, a parasitic infection spread by a nefarious vector, the Anopheles mosquito.

Mosquitoes’ own immune systems are more powerful than once thought, a new study in the journal Immunity shows. If properly harnessed, these immune mechanisms could help reduce the transmission of malaria, a disease which claims more than one million lives each year.

Cécile Frolet and her colleagues at the Institut de Biologie Moléculaire et Cellulaire in Strasbourg, France, manipulated the NF-kB gene in the gut of the mosquito, where the malaria parasite first takes up residence. NF-kB has been championed as a master immune gene, playing an integral role in switching on pathogen-fighting responses. In mosquitoes, NF-kB activates several genes that have been implicated in killing parasites, including Plasmodium, the parasite that causes malaria.

When Frolet silenced the NF-kB gene (using the Nobel Prize-winning technique known as RNA interference), the mosquitoes were unable to make the molecular factors they needed to kill the incoming parasite. These disarmed mosquitoes became more susceptible to infection and hosted more parasites in their guts. On the flip side of the experiment, mosquitoes with boosted NF-kB production made higher amounts of anti-parasitic factors, and their immune systems completely stymied parasite growth.

This study marks a big step in the possibility of using molecular mechanisms in the mosquito to kill the parasite before it ever has the chance to make it back into a new host. Indeed, Frolet and her colleagues demonstrate that by manipulating a single gene, they can achieve great responses against the malaria parasite.  In a world with ever-increasing drug-resistant parasites, learning how to harness such potent immune mechanisms may just be the next step in malaria control.