Tool uses smartphone to identify Aedes aegypti mosquitoes, Wolbachia
Researchers from the University of Texas developed a novel diagnostic tool to easily identify disease-spreading Aedes aegypti mosquitoes and detect whether they are carrying Wolbachia, a bacterium being used for mosquito control.
“Our easy-to-use and easy-to-interpret assays should facilitate widespread field mosquito surveillance with minimal instrumentation and high accuracy,” Sanchita Bhadra, PhD, research associate in the department of molecular biosciences at the University of Texas at Austin, told Infectious Disease News. “Modest technology requirements, minimal execution steps, simple yes/no readout, and robust accuracy make our assay platform well suited for use in austere or resource-limited conditions.”
To reduce the burden of mosquito-borne viruses, natural mosquito populations have been manipulated using Wolbachia, a bacterium approved by the EPA for mosquito control. However, current screening methods make observation of the efficacy and spread of the Wolbachia strategy difficult, according to Bhadra and colleagues.
In comparison, the new assay is “quite simple,” Bhadra said, and does not require many user-mediated steps. The assay is a nucleic acid diagnostic platform that uses loop-mediated amplification (LAMP) and oligonucleotide strand displacement (OSD) for the surveillance of vectors and symbionts.
“Individual or pools of mosquitoes are manually crushed, followed by transfer of a small portion of the macerated mosquito(es) directly into the one-pot assay that contains all the ingredients necessary to specifically recognize, amplify, and signal the presence of Wolbachia nucleic acids,” Bhadra explained.
The assay results are easily identified through visual observation, or by a photo taken on a smartphone. It will turn a bright fluorescent green if the mosquito is infected with Wolbachia but stays dark if the mosquito is uninfected.
Bhadra and colleagues found that their assay workflow simplified Wolbachia surveillance and reduced operational costs. The LAMP-OSD assay eliminated the need for nucleic acid extraction because it directly analyzes macerated mosquitoes. It also can accurately analyze samples after a delayed retrieval — up to 3 weeks — and does not require complex instruments for incubation and readouts.
“We have demonstrated a versatile nucleic acid diagnostic platform for accurate and rapid point-of-need analyses of both insect vectors and symbionts. The platform can also be readily reprogrammed for additional applications,” Bhadra said. “We are currently automating the assays and workflow on low-cost modular paper and plastic devices to further streamline diagnostic application, especially for high-throughput analysis.” – by Marley Ghizzone
Disclosures: The authors report no relevant financial disclosures.