Scientists in the US have come up with a novel way to detect the presence of SARS-CoV-2 in patients using a device attached to an ordinary smartphone. Upon further research, the new detection procedure can enable easy detection of Coronavirus among masses within minutes.
Now published in the?journal Cell, the study speaks of a test that uses?CRISPR-Cas technology. The technology employs Cas13 enzymes to detect the RNA in nasal swab samples. This eliminates the need for reverse transcription of the RNA into DNA and the subsequent amplification by PCR technology, as used in current standard tests.
The Cas13 in this case binds to the?RNA from the virus, thus splitting the bond of any surrounding RNA sequences. The researchers added an RNA-based test to the reaction, which gets cleaved to produce?fluorescence. This fluorescence can further be detected with the camera.
The whole assay promises to provide results within 30 minutes of the conducted test. "Our study shows that we can do the detection part of this assay very quickly, making the measurement with mass-produced consumer electronics," says Daniel Fletcher, a bioengineer at the University of California in Berkeley and co-senior author on the paper. "We don't need fancy laboratory equipment."
Another big plus of the novel method is that it does not require amplification. The assay is thus able to quantify the amount of virus in the sample. "It's super exciting to have this quantitative aspect in the assay," says Melanie Ott, a virologist at Gladstone Institutes and the University of California, San Francisco and a co-senior author on the research. "PCR is the gold standard, but you have to go through so many steps. There are huge opportunities here for pathogens and for biology in general to make RNA quantification more precise."
The new method for SARS-CoV-2 detection originated from the idea of a rapid, at-home test for HIV that the authors of the research had earlier been working on along with Nobel laureate Jennifer Doudna. With the onset of the Coronavirus pandemic, the research was quickly pivoted to detect the presence of SARS-CoV-2 instead.
The method uses a mobile phone-based fluorescence microscope and reaction chamber, that involves a fluorescence detector composed of a laser and an added lens. The laser is used to produce illumination and excite the fluorescence while the lens helps collect the light. The phone is placed on top for this detection.
¡°The goal was to show that mass-produced consumer electronics, rather than specialized laboratory equipment, are sufficient to capture the small fluorescent signals generated by Cas13a direct detection,¡± the scientists note in the study. Interestingly, they found that mobile phones were in fact better detectors than the plate reader used in the development of this assay due to ¡°reduced measurement noise and the ability to collect more time points.¡±
With the development, the researchers hope to develop a new testing device using this technology that could be rolled out to pharmacies and drop-in clinics. They would also like to bring the cost of the assay down and going forward, possibly use it to detect other pathogens in the human body.