A new system for tropical disease research spares people and animals mosquito bites.
Researchers are working to take some of the pain out of studying the feeding behavior of mosquitoes. The insects’ bites can spread diseases like malaria, dengue, and yellow fever, but setting up experiments to examine their behavior can take a big bite out of lab budgets.
“Many mosquito experiments still rely on human volunteers and animal subjects,” says Kevin Janson, a graduate student in bioengineering at Rice University and lead coauthor of a study in Frontiers in Bioengineering and Biotechnology. Live subject testing can be expensive, and Janson says the “data can take many hours to process.”
So he and his coauthors found a way to automate the collection and processing of that data using inexpensive cameras and machine-learning software. To eliminate the need for live volunteers, their system uses patches of synthetic skin made with a 3D printer. Each patch of gelatin-like hydrogel comes complete with tiny passageways that can be filled with flowing blood.
To create the stand-ins for skin, the team used bioprinting techniques that were pioneered in the lab of former Rice professor Jordan Miller.
For feeding tests, as many as six of the hydrogels can be placed in a transparent plastic box about the size of a volleyball. The chambers are surrounded with cameras that point at each blood-infused hydrogel patch. Mosquitos go in the chamber, and the cameras record how often they land at each location, how long they stay, whether or not they bite, how long they feed, etc.
Researchers in the laboratory of Dawn Wesson, associate professor of tropical medicine at Tulane University, tested the system. Wesson’s research group has facilities for breeding and testing large populations of mosquitoes of varying species.
In the proof-of-concept experiments featured in the study, Wesson, Janson, and coauthors used the system to examine the effectiveness of existing mosquito repellents made with either DEET or a plant-based repellent derived from the oil of lemon eucalyptus plants. Tests showed mosquitoes readily fed on hydrogels without any repellent and stayed away from hydrogel patches coated with either repellent. While DEET was slightly more effective, both tests showed each repellent deterred mosquitoes from feeding.
Omid Veiseh, the study’s corresponding author and an assistant professor of bioengineering at Rice, says the results suggest the behavioral test system can be scaled up to test or discover new repellents and to study mosquito behavior more broadly. He says the system also could open the door for testing in labs that couldn’t previously afford it.
“It provides a consistent and controlled method of observation,” Veiseh says. “The hope is researchers will be able to use that to identify ways to prevent the spread of disease in the future.”
Wesson says her lab is already using the system to study viral transmission of dengue, and she plans to use it in future studies involving malaria parasites.
“We are using the system to examine virus transmission during blood feeding,” Wesson says. “We are interested both in how viruses get taken up by uninfected mosquitoes and how viruses get deposited, along with saliva, by infected mosquitoes.
“If we had a better understanding of the fine mechanics and proteins and other molecules that are involved, we might be able to develop some means of interfering in those processes,” she says.
The Robert J. Kleberg, Jr. and Helen C. Kleberg Foundation supported the research.
Source: Rice University