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To curb the COVID-19 pandemic, rapid and specific identification of those infected with SARS-CoV-2 is essential. Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) is the current diagnostic standard. Despite its high sensitivity, it requires specialized and expensive equipment, trained personnel, and has a relatively long turnaround time (TAT) of 2 to 4 hours. An alternative method, isothermal reverse transcriptase loop mediated isothermal amplification (RT-LAMP) combined with Cas12 detection (RT-Cas12-RNP), does not need specialized equipment, is highly sensitive and specific, and has a TAT of <30 minutes. This technology has been called DNA endonuclease-targeted CRISPR trans reporter (DETECTR).
In this study, supported by the Dutch government, RT-LAMP and RT-Cas12-RNP were each less sensitive than their combination, DETECTR. Using 378 clinical samples from local hospitals, the investigators found DETECTR to be 94.9% concordant with qRT-PCR. In 40 instances, lateral flow strips were used for read-out. These results were 100% concordant with using a high-throughput spectrophotometer. Finally, eight samples that were uninterpretable by qRT-PCR were delineated clearly as positive or negative by DETECTR.
Brandsma E et al. Rapid, sensitive and specific SARS coronavirus-2 detection: A multi-center comparison between standard qRT-PCR and CRISPR based DETECTR. J Infect Dis 2020 Oct 10; [e-pub]. (https://doi.org/10.1093/infdis/jiaa641)
Comment
As the authors point out, DETECTR had comparable sensitivity and superior specificity to qRT-PCR. Moreover, using lateral flow strips, it could be used as a point-of-care test and, because it requires minimal equipment, is adaptable to resource-limited settings. Others have reported similar results with a CRISPR-reliant method. This is timely given the recently awarded Nobel Prize for chemistry awarded for the discovery of this technology. The next step will be for laboratories to operationalize this method for clinical use. We can hope that this will occur soon.