Aptamer-based surface plasmon resonance detection of legionella pneumophila in water systems ****************

军团病是由嗜肺军团菌（Lp）引起的。许多水系统，如冷却塔和热水分配系统，都可能被Lp污染。这种系统产生的气溶胶使Lp能够传播给人类。据报道，每年都有许多这种疾病的爆发。例如，魁北克市在2012年遭受了一次重大疫情。监测供水系统对于限制感染风险和疫情至关重要。水系统中Lp的检测目前是通过培养或qPCR进行的。这些方法既昂贵又乏味，而且在培养的情况下，需要长达两周的时间来完成。通过与Magnus Chemical Ltd的合作，我们提出了一种基于核酸适体识别Lp的新检测方法，核酸适体是一种短的DNA序列，可以折叠成与目标特异性结合的结构。该适体将使用“通过指数富集的配体系统进化”（SELEX）技术进行开发。该适体的特异性和多功能性将在Lp分离物和其他经常从水系统中分离出来的细菌物种的多样性中进行测试。将最佳适配体固定在表面等离子体共振生物传感器（SPR）棱镜表面，并评估其检测人造水样中Lp的能力。然后，该系统将通过修改表面化学和在“三明治试验”中使用第二个适配体耦合到金纳米颗粒来优化，以放大信号并提高检测限（LOD）。为了进一步降低LOD，将开发用于水样中Lp富集的Lab-on-a-Chip策略。目标是达到LOC 10-100 CFU Lp /ml（维持水平）。接下来，将用实际水样对新检测方法进行测试，并与现有检测方法进行比较。这个项目应该允许开发一种新的检测策略，这种策略可以小型化，并用于连续监测水系统中Lp的存在。从长远来看，该项目将改善及时反应，启动水系统的治疗，以尽量减少军团病的风险。**************************

Legionnaires' disease is caused by the bacterium Legionella pneumophila (Lp). Many water systems, such as cooling towers and hot water distribution systems, are potentially contaminated by Lp. Production of aerosols by such systems enables the transmission of Lp to humans. Many outbreaks of this disease are reported each year. For example, Quebec City suffered from a major outbreak in 2012. Surveillance of water systems is crucial for limiting infection risks and outbreaks. Detection of Lp in water systems is currently performed by culturing or qPCR. These methods are expensive and tedious, and in the case of culturing, take up to two weeks to perform. In collaboration with Magnus Chemical Ltd, we propose to develop a novel detection method based on the recognition of Lp by aptamers, short DNA sequences that folds into structures binding specifically to a target. The aptamers will be developed using the "Systemic Evolution of Ligands through EXponential enrichment" (SELEX) technique. Specificity and versatility of the aptamers will be tested against a diversity of Lp isolates and other bacterial species frequently isolated form water systems. The best aptamers will be immobilized on the surface of a Surface Plasmon Resonance biosensor (SPR) prism and their ability to detect Lp in man-made water samples will be evaluated. The system will then be optimized by modifying the surface chemistry and by using a second aptamer coupled to gold nanoparticle in a "sandwich assay" to amplify the signal and improve the limit of detection (LOD). To further lower the LOD, a Lab-on-a-Chip strategy will be developed for the Lp enrichment in water samples. The aim is to reach a LOC of 10-100 CFU Lp /ml (maintenance levels). Next, the novel detection method will be tested with real water samples and compared to the current detection methods. This project should allow the development of a novel detection strategy that could be miniaturized and used to monitor the presence of Lp in water systems in a continuous manner. At term, this project will improve timely response to initiate treatment of water systems to minimize risk of Legionnaires' disease.**************************