Rapid detection of Mycobacterium leprae RLEP by recombinase polymerase amplification: A pilot study

Early detection of leprosy is crucial since delayed treatment can result in deformities and impairments. Recombinase Polymerase Amplification (RPA) is an isothermal DNA amplification technique that amplifies DNA fragments at a single, moderate temperature using a mixture of recombinase enzymes. In this work, PCR-confirmed cases of leprosy (positive for Mycobacterium leprae DNA) were subjected to RPA targeting an in-house designed RLEP amplicon of 175 bp. Following amplification, the RPA amplicons were analysed using agarose gel electrophoresis and SYBR Green I. The RPA-based detection of M. leprae DNA can be achieved within 20 min at 39 °C. The analytical sensitivity of the test was 0.5 cells/µl when tested using purified M. leprae genomic DNA standards. The clinical performance of the RPA was evaluated using 28 DNA samples extracted from skin biopsies. This assay has greater potential for developing a quick, accessible and field-friendly method for the visual detection of M. leprae DNA.