USA: Novel Coronavirus Test This Low-Cost Test Tool Can Diagnose Covid-19 Variants in One Hour
Scientists have developed a low-cost, CRISPR-based platform that uses saliva samples to diagnose specific Covid-19 variants within just one hour.
Washington/USA — A new test platform can detect mutations associated with the B.1.1.7 (Alpha), B.1.351 (Beta), and P.1 (Gamma) SARS-CoV-2 variants and provides feedback through a smartphone app, which uses the phone’s camera to detect fluorescence that indicates a positive or negative result. The novel system could be rapidly scaled up and deployed in response to outbreaks and allows users to send their test results to an online database, which could offer a decentralized tool for tracking viral strains that may potentially threaten vaccine efficacy, the journal Science reports. While several concerning SARS-CoV-2 variants have spread widely, there is currently no point-of-care testing system to identify these variants rapidly.
To overcome this limitation, Helena de Puig and colleagues developed miSherlock (minimally instrumented specific high-sensitivity enzymatic reporter unlocking), which builds on Sherlock, a CRISPR/Cas platform that has been used to create ultrasensitive molecular diagnostics with simplified readouts for other viruses, including Zika. The researchers designed Sherlock assays that targeted a panel of key spike protein mutations representative of the N501Y, Y144del, and E484K mutations that correspond to each selected SARS-CoV-2 variant, systematically evaluating recombinase polymerase amplification (RPA) primer sets and guide RNAs (gRNAs) to determine the most sensitive combinations. To use the miSherlock system, the user places two milliliters of their saliva into a collector that contains lysis reagents, resulting in concentrated, purified RNA within three to six minutes once they activate the device’s heater. Next, the user transfers the sample to the reaction chamber, which provides visual fluorescence results readout within 55 minutes. As a next step, the authors plan to extend the miSherlock system to detect the Delta variant.
References: “Minimally Instrumented SHERLOCK (miSHERLOCK) for CRISPR-based Point-of-Care Diagnosis of SARS-CoV-2 and Emerging Variants” by H. de Puig et al.; Science Advances, doi: 10.1126/sciadv.abh2944;
This news was originally published by AAAS, the science society