Blocking Nonspecific Primer Amplification in Loop-Mediated Isothermal Amplification with TrueLAMP

Loop-mediated isothermal amplification (LAMP) is a rapid nucleic acid amplification technique suited for point-of-care testing but prone to nonspecific amplification and false positives, especially in colorimetric formats. We evaluated TrueLAMP, a polymerase formulation containing a proprietary inhibitor that selectively suppresses primer-driven nonspecific amplification while preserving target-specific reactions. Using both a semi-real-time colorimetric LAMP in a convection oven and an endpoint colorimetric LAMP in a water bath, TrueLAMP completely blocked amplification in no-template controls and maintained robust detection of RNA and DNA targets at 65 °C for 90 min. Using SARS-CoV-2 RNA as a model, TrueLAMP achieved a limit of detection of 250 RNA copies per reaction, with 96.9 % sensitivity and 100 % specificity. TrueLAMP substantially improves LAMP reliability and eliminates false-positive amplification, enabling accurate semi-real-time or endpoint colorimetric detection using unmodified, off-the-shelf equipment suitable for point-of-care and resource-limited diagnostics.