Putting the locks on mosquito-borne disease

From the deadly threat of malaria across Africa to the recent spread of painful chikungunya from the Caribbean into Florida, tiny mosquitoes play a big role in spreading debilitating and often fatal diseases. But researchers in the School of Biological Sciences (SBS) are closing in on a new way to significantly reduce mosquito-borne disease transmission rates by introducing a biological “handcuff” into the insect’s food supply.

Professor David Moffett, an expert in mosquito genomics, and Adelina Petrova, a post-doctoral researcher in Moffett’s laboratory, are testing a vaccine that targets the carrier rather than the disease.

Preliminary research indicates that, when a feeding mosquito ingests antibodies produced in the bloodstream of a vaccinated animal, the antibodies quickly disrupt the insect’s digestive process. Afterward, the mosquito no longer feeds nor lays eggs and the transmission cycle is stopped.

Targeted approach

Unlike generally toxic pesticides, such as DDT, or genus-specific chemicals that affect all arthropods—from mosquitoes, spiders, and gnats to environmentally sensitive lobster and shrimp—the antibodies in the new vaccine target specific gut cells in the mosquito.

“This technology could have a significant impact on reducing the transmission of disease,” said Petrova. “Imagine being able to vaccinate the domestic animals of a village to create a zone with fewer feeding mosquitoes, which in turn could prevent an outbreak of malaria or dengue fever.”

Working with the genome of one of the more common mosquitoes, Aedes aegypti, Moffett and Petrova identified a unique amino-acid string that occurs on the inside surface of the mosquito gut cell and developed a corresponding antibody. Just as the antibodies produced by a human measles vaccine attach to the measles virus and render it ineffective, the mosquito antibodies attach to the gut protein strings and disrupt their regular function.

 

“Imagine your entire body is a protein and you are introduced to an antibody that slaps a pair of handcuffs on your wrists. It would make it very difficult for you to go about your regular life,” said Moffett.

The long game

Vaccine research for mosquito control has been studied worldwide for more than half a century. Moffett’s research into the structure and biology of the mosquito gut began in late 1990s. Petrova, who completed her Ph.D. at Newcastle University in the U.K., studied plant-insect molecular interaction before coming to WSU in 2009.

After the team designed the biological markers to track specific protein regions of the mosquito gut cells, Petrova tried something new: she doped a sample of her own blood with the antibodies and fed it to the mosquitos. Within an hour, most of the feeding females were immobile or dead.

Having identified a suitable protein site for mosquito control, research is continuing to refine the antibody and document specifically how the function of the mosquito gut cells is altered.

Potential applications

Moffett and Petrova have compared the protein string with many other genomes and found very little overlap with other vertebrates or mammals. Since the antibody is highly specific to the mosquito gut, birds and other creatures that may feast on the dead mosquitos are unlikely to be affected.

The WSU researchers foresee multiple applications that could be developed to substantially reduce disease transmission around the world without harming larger ecosystems.