Colorimetric loop-mediated isothermal amplification (LAMP) for cost-effective and quantitative detection of SARS-CoV-2: the change in color in LAMP-based assays quantitatively correlates with viral copy number

We demonstrate a loop-mediated isothermal amplification (LAMP) method to detect and amplify SARS-CoV-2 genetic sequences using a set of in-house designed initiators that target regions encoding the N protein. We were able to detect and amplify SARS-CoV-2 nucleic acids in the range of 62 to 2 x 10(5) DNA copies by this straightforward method. Using synthetic SARS-CoV-2 samples and RNA extracts from patients, we demonstrate that colorimetric LAMP is a quantitative method comparable in diagnostic performance to RT-qPCR (i.e., sensitivity of 92.85% and specificity of 81.25% in a set of 44 RNA extracts from patients analyzed in a hospital setting).

Automated summary

The study demonstrated a loop-mediated isothermal amplification (LAMP) method using specially designed initiators to detect and amplify SARS-CoV-2 genetic sequences, showing a quantitative ability to detect nucleic acids in a range of 62 to 2 x 10(5) DNA copies. The colorimetric LAMP was found to have diagnostic performance comparable to RT-qPCR, with a sensitivity of 92.85% and specificity of 81.25% in analyzing a set of 44 RNA extracts from patients in a hospital setting.