A nanopore biosensor for leveling Mtb antigens in blood

点击翻译按钮获取中文摘要

Tuberculosis (TB) is a global health threat but can be difficult to diagnose and manage due to the sub-optimal performance and non-quantitative nature of frontline diagnostic assays, which require sputum or tissue biopsies and exhibit reduced performance when applied to diagnose paucibacillary or extrapulmonary TB cases. There is an unmet need for a rapid, non-sputum-based assay that can sensitively diagnose active TB and measure treatment responses in clinically diverse populations. We have previously reported that serum levels of two peptides derived from the Mycobacterium tuberculosis (Mtb) virulence factors CFP-10 and ESAT-6 can act as specific biomarkers of active TB and, using a mass spectrometry (MS) assay, validated their diagnostic performance in relevant cohorts of adults and children. This included HIV+/HIV-, pulmonary / extrapulmonary, and culture-positive / negative TB cases, as well as those with latent TB and nontuberculous mycobacteria infections. This MS assay had similar diagnostic sensitivity (88.6 vs 88.2%) and specificity (93.8 vs 97.2%) in adults and children and exceeded the reported performance of frontline tests in comparable populations. Serum Mtb antigen levels were also informative in monitoring anti-TB treatment responses. However, this MS assay is not suitable for use in resource limited settings. The proposed studies will therefore refine and evaluate the performance of a protein-based nanopore biosensor assay to diagnose active TB cases using the same serum biomarkers. This system is easy to operate, has low fabrication and instrument costs, and can perform high- throughput and ultra-sensitive measurements of specific Mtb-derived peptides. Its robust nature and portability also allow its use in resource-limited areas subject to high TB prevalence. Our results show that a nanopore assay can accurately detect CFP-10 and ESAT-6 peptides, and this data has significant diagnostic promise. Based on these findings, we propose that the portable protein nanopore biosensor assay that will be analyzed in these studies can improve TB diagnosis in adults and children, particularly in resource-limited areas with high TB prevalence. We will utilize this system to measure serum levels of Mtb antigen-derived peptide biomarkers in order to: (1) develop a sensitive and robust nanopore-based TB diagnostic assay; (2) validate this assay in well-organized cohorts, containing patients with pulmonary and extrapulmonary TB cases; and (3) evaluate how serum levels of Mtb antigens change in adult PTB cases in during anti-TB therapy. Given the success of these proof-of-concept studies, the long-term goal of the proposed research program is to build prototype devices for large-scale on-site clinical validation studies in high TB burden regions, and to modify and extend this system to detect other disease biomarkers. This research program should hasten the translation of a promising biosensor platform into a practical assay suitable for rapid translation to clinical applications for disease diagnosis.