Dataset Information

Light Forge: A Microfluidic DNA Melting-based Tuberculosis Test.

ABSTRACT: BACKGROUND:There is a well-documented lack of rapid, low-cost tuberculosis (TB) drug resistance diagnostics in low-income settings across the globe. It is these areas that are plagued with a disproportionately high disease burden and in greatest need of these diagnostics. METHODS:In this study, we compared the performance of Light Forge, a microfluidic high-resolution melting analysis (HRMA) prototype for rapid low-cost detection of TB drug resistance with a commercial HRMA device, a predictive "nearest-neighbor" thermodynamic model, DNA sequencing, and phenotypic drug susceptibility testing (DST). The initial development and assessment of the Light Forge assay was performed with 7 phenotypically drug resistant strains of Mycobacterium tuberculosis (M.tb) that had their rpoB gene subsequently sequenced to confirm resistance to Rifampin. These isolates of M.tb were then compared against a drug-susceptible standard, H37Rv. Seven strains of M.tb were isolated from clinical specimens and individually analyzed to characterize the unique melting profile of each strain. RESULTS:Light Forge was able to detect drug-resistance linked mutations with 100% concordance to the sequencing, phenotypic DST and the "nearest neighbor" thermodynamic model. Researchers were then blinded to the resistance profile of the seven M.tb strains. In this experiment, Light Forge correctly classified 7 out of 9 strains as either drug resistant or drug susceptible. CONCLUSIONS:Light Forge represents a promising prototype for a fast, low-cost diagnostic alternative for detection of drug resistant strains of TB in resource constrained settings.

SUBMITTER: Mbano IM

PROVIDER: S-EPMC7192548 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature

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Light Forge: A Microfluidic DNA Melting-based Tuberculosis Test.

Mbano Ian M IM Mandizvo Tawanda T Rogich Jerome J Kunota Tafara T R TTR Mackenzie Jared S JS Pillay Manormoney M Balagaddé Frederick K FK

The journal of applied laboratory medicine 20200501 3

<h4>Background</h4>There is a well-documented lack of rapid, low-cost tuberculosis (TB) drug resistance diagnostics in low-income settings across the globe. It is these areas that are plagued with a disproportionately high disease burden and in greatest need of these diagnostics.<h4>Methods</h4>In this study, we compared the performance of Light Forge, a microfluidic high-resolution melting analysis (HRMA) prototype for rapid low-cost detection of TB drug resistance with a commercial HRMA device ...[more]

PMID: 32445364

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Project description:There is a growing awareness that molecular diagnostics for detect-to-treat applications will soon need a highly multiplexed mutation detection and identification capability. In this study, we converted an open-amplicon microarray hybridization test for multidrug-resistant (MDR) Mycobacterium tuberculosis into an entirely closed-amplicon consumable (an amplification microarray) and evaluated its performance with matched sputum and sediment extracts. Reproducible genotyping (the limit of detection) was achieved with ∼25 M. tuberculosis genomes (100 fg of M. tuberculosis DNA) per reaction; the estimated shelf life of the test was at least 18 months when it was stored at 4°C. The test detected M. tuberculosis in 99.1% of sputum extracts and 100% of sediment extracts and showed 100% concordance with the results of real-time PCR. The levels of concordance between M. tuberculosis and resistance-associated gene detection were 99.1% and 98.4% for sputum and sediment extracts, respectively. Genotyping results were 100% concordant between sputum and sediment extracts. Relative to the results of culture-based drug susceptibility testing, the test was 97.1% specific and 75.0% sensitive for the detection of rifampin resistance in both sputum and sediment extracts. The specificity for the detection of isoniazid (INH) resistance was 98.4% and 96.8% for sputum and sediment extracts, respectively, and the sensitivity for the detection of INH resistance was 63.6%. The amplification microarray reported the correct genotype for all discordant phenotype/genotype results. On the basis of these data, primary sputum may be considered a preferred specimen for the test. The amplification microarray design, shelf life, and analytical performance metrics are well aligned with consensus product profiles for next-generation drug-resistant M. tuberculosis diagnostics and represent a significant ease-of-use advantage over other hybridization-based tests for diagnosing MDR tuberculosis.

Project description:Cell-free DNA (cfDNA) is a liquid biopsy marker that can carry signatures (i.e., mutations) associated with certain pathological conditions. Therefore, the extraction of cfDNA from a variety of clinical samples can be an effective and minimally invasive source of markers for disease detection and subsequent management. In the oncological diseases, circulating tumor DNA (ctDNA), a cfDNA sub-class, can carry clinically actionable mutations and coupled with next generation sequencing or other mutation detection methods provide a venue for effective in vitro diagnostics. However, cfDNA mutational analyses require high quality inputs. This necessitates extraction platforms that provide high recovery over the entire ctDNA size range (50 ? 150 bp) with minimal interferences (i.e., co-extraction of genomic DNA), and high reproducibility with a simple workflow. Herein, we present a novel microfluidic solid-phase extraction device (?SPE) consisting of a plastic chip that is activated with UV/O3 to generate surface-confined carboxylic acid functionalities for the ?SPE of cfDNA. The ?SPE uses an immobilization buffer (IB) consisting of polyethylene glycol and salts that induce cfDNA condensation onto the activated plastic microfluidic surface. The ?SPE consists of an array of micropillars to increase extraction bed load (scalable to loads >700 ng of cfDNA) and can be produced at low-cost using replication-based techniques. The entire ?SPE can be fabricated in a single molding step negating the need for adding additional extraction supports to the device simplifying production and keeping device and assay cost low. The ?SPE allowed for recoveries >90% of model cfDNA fragments across a range of sizes (100-700 bp) and even the ability to extract efficiently short cfDNA fragments (50 bp, >70%). In addition, the composition of the IB allowed for reducing the interference of co-extracted genomic DNA. We demonstrated the clinical utility of the ?SPE by quantifying the levels of cfDNA in healthy donors and patients with non-small-cell lung and colorectal cancers. ?SPE extracted cfDNA from plasma samples was also subjected to a ligase detection reaction (LDR) for determining the presence of mutations in the KRAS gene for colorectal and non-small cell lung cancer patients.

Dataset Information

Light Forge: A Microfluidic DNA Melting-based Tuberculosis Test.

Publications

Light Forge: A Microfluidic DNA Melting-based Tuberculosis Test.

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