Focusing on “the deadliest animal on Earth,” an Indiana University biologist is trying to cripple a dangerous killer: the mosquito. While mostly just a nuisance swatted away in the U.S., IU Biology Associate Professor Dr. Irene Newton says, “you can think of the mosquito as the apex predator on the planet, because the diseases it carries kill so many people.” A recent $1.8 million National Institutes of Health grant is funding her five-year mission to decode how basic biology could stop the spread of vector-borne diseases in the world’s most vulnerable regions.
Vector-borne diseases such as West Nile virus, dengue and malaria are prevalent in tropical and sub-tropical regions. Dengue, a mosquito-borne infection, is the world’s fastest growing vector-borne disease, increasing 30-fold in the last 50 years.
Funded by her biggest award yet, Newton’s project focuses on how the biology of the actual mosquito could defeat its ability to spread disease. Her work focuses on a specific microbe called Wolbachia, which is present in about half of all insects. Scientists have recently discovered almost all animals have microbes, and some of them are beneficial, such as human “gut” microbes.
In 2008, researchers discovered Wolbachia limits the replication of viruses, “so, immediately, it would seem that this could be something we could use in vector control.” Through other advances in research, scientists are now able to take Wolbachia from fruit flies—in which it’s prevalent—and inject the organism into mosquitos.
“These mosquitos with Wolbachia in them are [uncooperative] to virus replication,” says Newton. “In other words, say these Wolbachia-infected mosquitos bite a person that is infected with dengue and take up a blood meal. Then, that dengue virus does not replicate in the mosquito, so when the mosquito goes and bites an uninfected person, it doesn’t transmit the disease. This is a boon to us; we can release Wolbachia-infected mosquitos all over the world to prevent disease transmission.”
Furthermore, in insects—including mosquitos—Wolbachia is transmitted from mother to offspring, creating a method of vector control. While only female mosquitos bite, male and female mosquitos are released; the females will reproduce offspring that have Wolbachia, and over time, Wolbachia takes over the population. Therefore, almost all of the mosquitos have Wolbachia and would be resistant to virus replication.
To take full advantage of Wolbachia-based methods of insect control, Newton says researchers must decode the biology behind it. The recent $1.8 million grant will support her lab as it aims to understand Wolbachia’s mechanisms.
“We are studying how Wolbachia actually gets into the insect and is sufficiently transmitted to every generation. How does it achieve that colonization?” says Newton. “For Wolbachia to be used to control disease vectors or other vectors on the planet, we have to understand what it needs to be able to colonize. The goal of this project is to figure that out.”
If Newton’s team can pinpoint what Wolbachia needs to move into new insect populations, scientists could expand the use of the organism for many different contexts. Newton theorizes similar strategies could address vectors for pathogens that affect agricultural crops or insects like Drosophila suzukii, which are fruit flies that infest ripening fruit crops in California.
“This virus protection phenomena was first discovered doing basic research; [the scientists] stumbled upon this interesting discovery because of basic science,” says Newton. “I want the general public to understand, sometimes we can’t tell where basic research is going to go. It leads to new discoveries we couldn’t have imagined in retrospect.”
Newton says companies are using another Wolbachia-based method to “crash” mosquito populations.
Newton says IU’s world-class facility in fruit fly genetics makes the university, “hands-down,” the best place to do her work.