Glow-in-the-dark proteins could aid in analyzing viral nucleic acids

April 05, 2023 | Biotechnology

In preparing samples or interpreting results for viral diseases, current highly sensitive diagnostic tests require complicated techniques which makes them impractical for point-of-care settings or areas with few resources. To address this, the American Chemical Society (ACS Central Science) devised a comparable sensitive method that analyzes viral nucleic acids in a short period of time. It can be completed in one step - ‘glow-in-the-dark’ proteins.

Bioluminescence, a scientific phenomenon, is caused by a chemical reaction including luciferase proteins. This protein has been utilized in sensors to emit an easily observable light once they find their target, making these sensors ideal for point-of-care testing. However, they still lack the high sensitivity required of clinical diagnostic tests.

CRISPR, a gene-editing technique, can provide that ability but it requires various steps and additional specialized equipment. This led Maarten Merkz and colleagues to use CRISPR-related proteins with a bioluminescence technique whose signal can be perceived with just a digital camera.

They performed a recombinase polymerase amplification (RPA) to ensure there was enough sample of RNA or DNA to analyze. Together with luminescent nucleic acid sensor (LUNAS), two CRISPR/Cas9 proteins particular for the viral genome’s different neighboring parts will have a luciferase fragment attached to them. When the viral genome the researchers are testing for was present, the CRISPR/Cas9 proteins would tie the targeted nucleic acid sequences together, a mechanism that allows the luciferase proteins to form and shine a blue light in the presence of a chemical substrate. To indicate that the substrate was being used up, the researchers made use of a control reaction that shone green. A tube that changed from green to blue accounted for a positive result.

RPA-LUNAS was able to successfully detect SARS-CoV-2 RNA within 20 minutes, even at low concentrations of 200 copies per microliter when tested on clinical samples obtained from nasal swabs. With these results, the LUNAS assay shows great potential for detecting other viruses effectively and easily.