The refinement of leprosy PCR diagnostics by the amplification of specie-specific repeated fragment of the Mycobacterium leprae genome.

Abstract

Certain level of new registered cases of leprosy in a number of endemic countries in the world, as well as growing rate of transboundary migratory flows, raise the issue of effective diagnosis of this disease in countries with sporadic incidence of leprosy, including the Russian Federation. The purpose of the study was to develop a highly sensitive PCR test for detecting the genetic material of Mycobacterium leprae and to compare the test robustness and sensitivity with the commercially available Leprosy Genesig Standard Kit (Primerdesign Ltd., UK). The proposed approach uses real time PCR of non-coding repeating element RLEP, unique for the M. leprae genome, using TaqMan probe. The high test specificity was shown using the reference DNA samples of pathogenic and conditionally pathogenic mycobacterium, as well and its comparison with single-copy genes of M. leprae (rrs, fbp, MntH) PCR detection. The use of a commercially available test system based on the single-copy rpoB gene detection provided 59.4% sensitivity to the detection of M. leprae in the clinical material, while the application of the developed approach increased this index to 96.8%. The developed PCR diagnostics test of leprosy is submitted for state clinical approval process, whereupon the practical use of the test diagnostics allows solving a wide range of tasks to identify and confirm new cases of leprosy, and monitoring both the effectiveness of leprosy treatment, and epidemiological (including transboundary) the spread of the disease.