Use of visual loop-mediated isotheral amplification of rimM sequence for rapid detection of Mycobacterium tuberculosis and Mycobacterium bovis
ABSTRACT Mycobacterium tuberculosis and Mycobacterium bovis are pathogenic bacterial species in the genus Mycobacterium and the causative agents of most cases of tuberculosis (TB). Detection of M. tuberculosis and M. bovis using conventional culture- and biochemical-based assays is time-consuming and laborious. Therefore, a simple and sensitive method for rapid detection has been anxiously awaited. In the present study, a visual loop-mediated isothermal amplification (LAMP) assay was designed from the rimM (encoding 16S rRNA-processing protein) gene sequence and used to rapidly detect M. tuberculosis and M. bovis from clinical samples in South China. The visual LAMP reaction was performed by adding calcein and manganous ion, allowing the results to be read by simple visual observation of color change in a closed-tube system, and which takes less than 1 h at 65 degrees C. The assay correctly identified 84 M. tuberculosis isolates, 3 M. bovis strains and 1 M. bovis BCG samples, but did not detect 51 non-tuberculous mycobacteria (NTM) isolates and 8 other bacterial species. Sensitivity of this assay for detection of genomic DNA was 1 pg. Specific amplification was confirmed by the ladder-like pattern of gel electrophoresis and restriction enzyme HhaI digestion. The assay successfully detected M. tuberculosis and M. bovis not only in pure bacterial culture but also in clinical samples of sputum, pleural fluid and blood. The speed, specificity, sensitivity of the rimM LAMP, the lack of a need for expensive equipment, and the visual readout show great potential for clinical detection of M. tuberculosis and M. bovis.
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ABSTRACT: Loop-mediated isothermal amplification (LAMP), a novel DNA amplification technique, is widely used in molecular diagnosis although it is very easy to be contaminated by the huge amount of its own amplicons. An improved visual LAMP method for the event specific identification of GM rice TT51-1 and a rice endogenous reference gene (sucrose phosphate synthase, SPS) was established. Pre-loaded calcein and manganous ion into the LAMP reaction offered not only an easy way to read results by colour change from orange to green but also a closed-tube system to reduce contaminations caused by amplification products. The LAMP assays could be finished within 60 min, and the limits of detection (LODs) were estimated as low as 10 and 20 copies of rice haploid genomic DNA, respectively, about 10-fold more sensitive than that of conventional PCR. The specificities of the assays were also well evaluated with optimized system and conditions. The developed one-step visual LAMP assays in this study provided a promising tool for the convenient and effective detection of GM crops.Food Science and Technology Research 01/2014; 20(1-1):71-77. DOI:10.3136/fstr.20.71 · 0.36 Impact Factor
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ABSTRACT: We developed and evaluated the specificity and sensitivity of a loop-mediated isothermal amplification (LAMP) method for rapid detection of the multidrug-resistance gene cfr. A pair of outer primers and a pair of inner primers and one loop primer were specially designed for recognizing seven distinct sequences on the target cfr gene. The amplification reaction was performed within only 35 min under isothermal conditions at 63 °C in a regular water bath with visual measurement. The LAMP assay showed higher sensitivity than the conventional PCR, with a detection limit of 1 pg per tube of chicken Staphylococcus sciuri genomic DNA. The detection rate of cfr gene for 50 Staphylococcus clinical strains by LAMP assays was 16% and appeared 100% consistence with the result by PCR method. The LAMP method reported here demonstrated a potential and valuable means for detection of the multidrug-resistance gene cfr: easy, rapid, visual, specific, accurate and sensitive, especially useful for on-the-spot investigation.Gene 05/2012; 504(1):140-3. DOI:10.1016/j.gene.2012.04.049 · 2.08 Impact Factor
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ABSTRACT: Current methods of TB diagnosis are time consuming and less suited for developing countries. The LAMP (loop mediated isothermal amplification) is a rapid method more suitable for diagnosis in resource limited settings and has been proposed as a viable test requiring further evaluation for use as a laboratory method as well. We evaluated two LAMP assays, using culture lysates of clinical sputum samples (from Southern India) and compared it to a proprietary multiplex PCR reverse-hybridization line probe assay ('GenoType MTBC' from HAIN Lifescience GmbH, Germany). The LAMP procedure was modified to suit the local conditions. The Mycobacterium tuberculosis specific LAMP assay ('MTB LAMP') showed sensitivity and specificity, of 44.7% and 94.4% respectively in a 60 min format, 85.7% and 93.9% respectively in a 90 min format and 91.7%, and 90.9% respectively in a 120 min format. The Mycobacteria universal LAMP assay ('Muniv LAMP') showed a sensitivity of 99.1%. The LAMP was shown to be a rapid and accessible assay for the laboratory identification of M. tuberculosis isolates. Initial denaturation of template was shown to be essential for amplification in unpurified/dilute samples and longer incubation was shown to increase the sensitivity. The need for modification of protocols to yield better efficacy in this scenario needs to be addressed in subsequent studies.Journal of microbiological methods 10/2010; 84(1):71-3. DOI:10.1016/j.mimet.2010.10.015 · 2.10 Impact Factor