Researchers at Eindhoven University of Technology in the Netherlands have developed a sensitive diagnostic test for viral pathogens that is suitable for use in low-resource regions. The test is based on CRISPR proteins that can detect viral genetic material but also incorporates luciferase proteins, which are bioluminescent proteins that are naturally found in fireflies and other creatures. Two CRISPR/Cas proteins are specific for different parts of the viral genome, and when they both bind to target nucleic acid sequences they join together, uniting two fragments of luciferase and initiating a bioluminescent signal. The results can be appraised using a simple digital camera, meaning that the inexpensive technology may be suitable for use in low-resource regions.
The COVID-19 pandemic created the societal pressures that often accompany technological breakthroughs, and we can see evidence of this in the rapid creation and adoption of new vaccines, propelling mRNA technologies into the open. However, diagnostic technologies have also made a leap forward, with a variety of approaches that have been developed to detect viruses.
While many such approaches are valuable, they are not useful in every corner of the world. For instance, low-resource and/or remote regions often lack the qualified healthcare staff or laboratory resources to use these technologies effectively. To address this, these researchers have developed a simple viral diagnostic assay that combines the sensitivity of more advanced clinical tests with ease of use and rapid results.
The technology employs the CRISPR/Cas gene editing system which can detect viral genetic material, such as that from the Sars-CoV-2 virus. However, conventional use of CRISPR/Cas requires multiple steps and sophisticated equipment, particularly if the amount of genetic material in the sample is very low. To make the system more user-friendly, the researchers combined CRISPR-Cas with luciferase, a naturally-occurring bioluminescent protein.
The researchers have called their technique LUNAS (luminescent nucleic acid sensor). The technology involves recombinase polymerase amplification, a method to amplify nucleic acids that does not require high temperatures or sophisticated thermocyclers, but works at a constant temperature of approximately 100 F (38 C).
The system also includes CRISPR-Cas proteins that are attached to a fragment of the luciferase protein. When the proteins bind the viral nucleic acids they also bind to each other, reuniting the luciferase fragments and sparking a burst of bioluminescence that can easily be appraised using a smartphone camera. Finally, the technology can provide a result in as little as 20 minutes.
Study in journal ACS Central Science: Glow-in-the-Dark Infectious Disease Diagnostics Using CRISPR-Cas9-Based Split Luciferase Complementation