Laboratorio de Bioinformática y Biología Molecular, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú.
Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
PLoS One. 2020 Oct 28;15(10):e0241067. doi: 10.1371/journal.pone.0241067. eCollection 2020.
Tuberculosis (TB) is a major global public health problem with high mortality and morbidity. In low-middle income countries (LMIC) a large number of respiratory symptomatic cases that require TB screening per year demands more accurate, fast and affordable testing for TB diagnostics. Sputum smear is the initial screening test in LMICs, however, its sensitivity is limited in patients with low sputum bacilli load. The same limitation is observed in the currently available molecular tests. We designed, standardized and evaluated an electrochemical biosensor that detects the highly specific DNA insertion element 6110 (IS6110). A PCR amplified DNA product is hybridized on the surface of the working electrode built on FTO-Glass with immobilized specific DNA probes, after which cyclic voltammetry is performed with an Ag/AgCl reference electrode and a platinum counter electrode. The response of the sensor was measured by the ratio (cathodic peak current of the hybridized sensor) / (cathodic peak current of the non-hybridized sensor). We tested the biosensor, using positive hybridization control sequences, genomic DNA extracted from M. tuberculosis strains and sputum of TB patients, and extracted DNA from the urine of healthy controls spiked with M. tuberculosis DNA. This biosensor was effective for the detection of M. tuberculosis DNA with a detection limit of 16 fM in sputum sample and 1 fM in spiked urine samples. The low cost and the relatively brief duration of the assay make this an important TB screening tool in the fight against tuberculosis.
结核病(TB)是一个重大的全球公共卫生问题,具有高死亡率和发病率。在中低收入国家(LMIC),每年有大量需要进行结核病筛查的呼吸道症状病例,这就需要更准确、快速和经济实惠的结核病诊断检测方法。痰涂片是 LMIC 中最初的筛查试验,但其在低痰菌载量患者中的敏感性有限。目前可用的分子检测方法也存在同样的局限性。我们设计、标准化和评估了一种电化学生物传感器,该传感器可检测高度特异性的 DNA 插入元件 6110(IS6110)。PCR 扩增的 DNA 产物在 FTO-玻璃工作电极表面杂交,然后用 Ag/AgCl 参比电极和铂对电极进行循环伏安法。通过(杂交传感器的阴极峰电流)/(未杂交传感器的阴极峰电流)的比值来测量传感器的响应。我们使用阳性杂交对照序列、从结核分枝杆菌菌株和结核病患者的痰液中提取的基因组 DNA 以及用结核分枝杆菌 DNA 污染的健康对照者尿液中提取的 DNA 测试了该生物传感器。该生物传感器可有效检测结核分枝杆菌 DNA,在痰液样本中的检测限为 16 fM,在污染尿液样本中的检测限为 1 fM。该检测方法成本低,检测时间相对较短,是抗击结核病的重要结核病筛查工具。