Multiple Endonuclease Restriction Real-Time Loop-Mediated Isothermal Amplification: A Novel Analytically Rapid, Sensitive, Multiplex Loop-Mediated Isothermal Amplification Detection Technique

Abstract

Loop-mediated isothermal amplification (LAMP) is restricted to detecting a single target, limiting the usefulness of this method. To achieve multiplex LAMP-based detection, we developed a novel approach we called the multiple endonuclease restriction real-time-LAMP assay. In this system, the LAMP forward or backward inner primers contain 5' end short sequences that are recognized by the restriction endonuclease Nb.BsrDI, and the new forward or backward inner primers were modified at the 5' end with a fluorophore and in the middle with a dark quencher. Nb.BsrDI digests the newly synthesized double-stranded terminal sequences (5' end short sequences and their complementary sequences), which releases the quenching, resulting in a gain of signal. The assay permitted real-time detection of single or multiple target sequences in a single tube, and the positive results can be obtained in as short as 12 minutes. The novel methodology is highly efficient and specific, detecting down to 250 fg of DNA per reaction of Listeria DNA tested, and was successful in evaluating raw meat samples. The multiple endonuclease restriction real-time-LAMP technology, which is an extension of LAMP to accommodate robust, target-specific, and multiplex detection, provides a molecular diagnostic tool with less detection time and high sensitivity and specificity compared with those of LAMP and quantitative real-time PCR.