A global issue, dengue fever kills more than 20,000 individuals every year, most of whom are children, according the Centers for Disease Control and Prevention. Forty percent of the world’s population live in areas with a risk of dengue transmission. The World Health Organization reports that 50 to 100 million infections occur each year.
Dengue fever is something Susanta Behura has seen firsthand. Behura, an assistant research professor in bioinformatics and computational biology in the University of Missouri College of Agriculture, Food and Natural Resources, hails from India. He has several close relatives and friends who have been hospitalized from the disease. Symptoms of dengue fever include severe headaches, a high temperature, pain behind the eyes, severe joint and muscle pain, fatigue, nausea, vomiting, and skin rash. The virus, spread through human-to-mosquito-to-human means, is most common in tropical regions.
“Mosquitoes create huge problems in terms of the diseases that they can spread,” said Behura, who is an assistant research professor in the Division of Animal Sciences. “We don’t see a lot of these diseases in the United States, such as dengue, Zika and chikungunya, so we don’t fully realize the impact those diseases have across the world.”
For the past eight years, Behura has been researching mosquitoes and their genetics in an attempt to combat a mosquito’s ability to spread disease. His research began at the University of Notre Dame and has continued at MU. Behura officially joined Mizzou in December 2015.
Behura and his colleagues have most recently been studying tRNA fragments, small sections of transfer RNA molecules, which play active roles in the biology of diverse organisms. The team has found that these tRNA fragments (tRFs) have important functions in Aedes aegypti mosquitos as well. These mosquitoes serve as the main global spreader of diseases such as dengue fever, Zika and chikungunya.
“Basically, we’re developing mountains of data through sequencing genomes,” Behura said. “We have this tiny insect and it’s capable of spreading such awful and dreadful diseases. It’s a huge problem. These viruses easily mutate and they evolve extremely fast. The best practice is to stay away from mosquitoes or find ways to stop them from spreading disease. It’s really difficult to stay completely away from Aedes aegypti, as it bites in the day time. Use of a bed net is not an option, so hopefully we begin the process of making them incapable of spreading disease.”
The team examined tRF abundance in the Aedes aegypti mosquito. They identified 55 tRFs that are expressed in different biological samples from this mosquito, and each of those tRFs originated from a unique tRNA molecule.
The research has been focused solely on dengue fever. The team examined tRF responses to several factors, such as sex, strain, developmental stage, and exposure to dengue virus, blood or antibiotics. The researchers found a specific tRF that was expressed in a different way when exposed to each of the factors.“Mosquitoes create huge problems in terms of the diseases that they can spread. We don’t see a lot of these diseases in the United States, such as dengue, Zika and chikungunya, so we don’t fully realize the impact those diseases have across the world.”
The specific tRF looks to be an encouraging candidate for further research.
“We really want to target this tRF and see if it’s a starting point to figuring out how to stop mosquitoes from spreading disease,” Behura said. “There are certain enzymes which facilitates the release of this tRF. We want to stop the enzymes from binding so that the tRF doesn’t release.”
Only adult female mosquitoes transmit disease. Male mosquitoes don’t bite or take blood. Once a mosquito bites a person who has dengue fever, it takes seven or eight days for the virus to manifest. Once they bite a different person, it takes another 10 days or so for that person to develop symptoms.
“The goal is to block that tRF so that when the mosquito gets the virus, it won’t be able to replicate it and then transmit to humans by biting,” Behura said.
Multiple Aedes aegypti strains, originally collected from different parts of the world, were investigated in this research. The group did molecular analysis of the strains, looking at the genome and sequencing it.
Funding for the research was supported in part by a Faculty Initiation Grant from the University of Notre Dame and grants from Fogarty International Center and National Institute of Allergy and Infectious Diseases at the National Institutes of Health (grants RO3-TW008138 and RO1-AI059342).