Rapid and highly sensitive one-tube colorimetric RT-LAMP assay for visual detection of SARS-CoV-2 RNA

Coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is a highly contagious disease. To tame the continuously raging outbreak of COVID-19, developing a cheap, rapid and sensitive testing assay is absolutely imperative. Herein, we developed a one-tube colorimetric RT-LAMP assay for the visual detection of SARS-CoV-2 RNA. The assay integrates Si–OH magnetic beads (MBs)-based fast RNA extraction and rapid isothermal amplification in a single tube, thus bypassing the RNA elution step and directly amplifying on-beads RNA molecules with the visualized results. This one-tube assay has a limit of detection (LOD) as low as 200 copies/mL for sample input volumes of up to 600 μL, and can be performed in less than 1 h from sample collection to result readout. This assay demonstrated a 100% concordance with the gold standard test RT-qPCR test by using 29 clinical specimens and showed high specificity. This one-tube colorimetric RT-LAMP assay can serve as an alternative platform for a rapid and sensitive diagnostic test for COVID-19 and is particularly suitable for use at community clinics or township hospitals.