[Detection of drug resistance genes of mycobacterium tuberculosis by rolling circle amplification technique with multicolor fluorescent probes].

The aim of this study was to construct a simple, rapid and ultra-sensitive optical biosensing technique based on rolling circle amplification (RCA), and to apply it to multiple detection of drug-resistant genes of mycobacterium tuberculosis. The common mutation sites of isoniazid, rifampicin and streptomycin resistance genes are katG315 (AGC➝ACC), rpoB531 (CAC➝TAC) and rpsL43 (AAG➝AGG). For these three gene sites, from February 2020 to May 2021, in the Department of Laboratory Medicine of the First Affiliated Hospital of Army Military Medical University, the padlock probe (PLP), primers and capture probes were designed. And a solid-phase RCA constant temperature amplification reaction system based on magnetic beads was constructed and the experimental parameters were optimized. The RCA products were accurately captured by the multicolor fluorescent probes (Cy3/Cy5/ROX), and the single-tube multiple detection of three mutation genes was realized. The sensitivity, specificity and linear range of this method were further verified. The results showed that the response range of katG315 in the same reaction system ranged from 1.0 pmol/L to 0.1 nmol/L. The response range of rpoB531 and rpsL43 ranged from 1.0 pmol/L to 50.0 pmol/L and 1.0 pmol/L to 20.0 pmol/L, and the method had good specificity and sensitivity, and could accurately identify single base mutations in mixed targets, with the minimum detection limit as low as 1.0 pmol/L. The recoveries of simulated serum samples were 95.0%-105.2%. In conclusion, the constant temperature amplification multiple detection method constructed in this study can quickly realize the single-tube multiple detection of three drug resistance mutation sites. This technology is low-cost, simple and rapid, and does not rely on large equipment, providing a new analysis method for pathogen drug resistance gene detection.本研究旨在构建基于核酸滚环扩增（RCA）的简便快速、超灵敏的光学生物传感技术，并将其运用于结核杆菌耐药相关基因的多重检测。本研究在2020年2月至2021年5月期间，于陆军军医大学第一附属医院检验科，针对异烟肼、利福平和链霉素耐药的高频基因突变位点katG315（AGC➝ACC）、rpoB531（CAC➝TAC）和rpsL43（AAG➝AGG），分别设计锁式探针（padlock probe，PLP）、引物和捕获探针，构建了基于磁珠的固相RCA恒温扩增反应体系，并进行了实验参数的优化。通过多色荧光探针（Cy3/Cy5/ROX）对RCA产物精准捕获与信号放大，实现了对3种突变基因的单管多重检测。进一步对该方法的灵敏度、特异性与线性范围等分析性能进行验证，结果显示同一反应体系中katG315的响应范围为1.0 pmol/L至0.1 nmol/L，rpoB531和rpsL43的响应范围为1.0 pmol/L至50.0 pmol/L和1.0 pmol/L至20.0 pmol/L，且该方法具有较好的特异度与灵敏度，在混合靶标中可精确识别单碱基突变，最低检出限低至1.0 pmol/L；在模拟血清样本的回收实验中，回收率可达95.0%~105.2%。综上，本研究构建的恒温扩增型多重检测方法可快速实现3种耐药突变位点的单管多重检测，该技术成本低廉、简便快速、不依赖大型设备，为病原体耐药基因检测提供了一种新的分析方法。.