Development and validation of direct RT-LAMP for SARS-CoV-2

We have developed a reverse-transcriptase loop mediated amplification (RT-LAMP) method targeting genes encoding the Spike (S) protein and RNA-dependent RNA polymerase (RdRP) of SARS-CoV-2. The LAMP assay achieves comparable limit of detection as commonly used RT-PCR protocols based on artificial targets, recombinant Sindbis virus, and clinical samples. Clinical validation of single-target (S gene) LAMP (N=120) showed a positive percent agreement (PPA) of 41/42 (97.62%) and negative percent agreement (NPA) of 77/78 (98.72%) compared to reference RT-PCR. Dual-target RT-LAMP (S and RdRP gene) achieved a PPA of 44/48 (91.97%) and NPA 72/72 (100%) when including discrepant samples. The assay can be performed without a formal extraction procedure, with lyophilized reagents which do need cold chain, and is amenable to point-of-care application with visual detection.