Cryptococcus neoformans is a leading cause of fungal brain infection, but the mechanism of dissemination and dynamics of cerebral infection following pulmonary disease are poorly understood. To address these questions, non-invasive techniques that can study the dynamic processes of disease development and progression in living animal models or patients are required. As such, bioluminescence imaging (BLI) has emerged as a powerful tool to evaluate the spatial and temporal distribution of infection in living animals. We aimed to study the time profile of the dissemination of cryptococcosis from the lung to the brain in murine models by engineering the first bioluminescent C. neoformans KN99α strain, expressing a sequence-optimized red-shifted luciferase. The high pathogen specificity and sensitivity of BLI was complemented by the three-dimensional anatomical information from micro-computed tomography (μCT) of the lung and magnetic resonance imaging (MRI) of the brain. These non-invasive imaging techniques provided longitudinal readouts on the spatial and temporal distribution of infection following intravenous, intranasal or endotracheal routes of inoculation. Furthermore, the imaging results correlated strongly with the fungal load in the respective organs. By obtaining dynamic and quantitative information about the extent and timing of brain infections for individual animals, we found that dissemination to the brain after primary infection of the lung is likely a late-stage event with a timeframe that is variable between animals. This novel tool in Cryptococcus research can aid the identification of host and pathogen factors involved in this process, and supports development of novel preventive or therapeutic approaches.

中文翻译：

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隐球菌病小鼠模型中真菌向大脑扩散的生物发光成像。

新型隐球菌是真菌性脑部感染的主要原因，但是人们对肺部疾病后脑部感染的传播机制和动力学了解甚少。为了解决这些问题，需要能够研究活体动物模型或患者中疾病发展和进展的动态过程的非侵入性技术。因此，生物发光成像（BLI）已经成为评估活体动物感染时空分布的有力工具。我们的目标是通过设计第一个生物发光的新形成梭状芽胞杆菌，研究鼠模型中从肺到大脑的隐球菌传播的时间特征。KN99α菌株，表达序列优化的红移荧光素酶。BLI的高病原体特异性和敏感性得到了肺微计算机断层扫描（μCT）和脑磁共振成像（MRI）的三维解剖信息的补充。这些非侵入性成像技术提供了静脉，鼻内或气管内接种途径后感染的时空分布的纵向读数。此外，成像结果与各个器官中的真菌负荷高度相关。通过获取有关单个动物脑部感染的程度和时间的动态和定量信息，我们发现，原发性肺部感染后向大脑的传播很可能是后期事件，其时限在动物之间是可变的。这个新颖的工具隐球菌研究可以帮助鉴定参与此过程的宿主和病原体因素，并支持开发新的预防或治疗方法。