Molecular Imaging Program at Stanford (MIPS), Department of Radiology, School of Medicine, Stanford University, Stanford, CA, USA.
Department of Biomedical Engineering, University of California, Davis, CA, USA.
Nat Commun. 2020 Apr 30;11(1):2102. doi: 10.1038/s41467-020-15818-4.
Adeno-associated viruses (AAVs) are typically single-stranded deoxyribonucleic acid (ssDNA) encapsulated within 25-nm protein capsids. Recently, tissue-specific AAV capsids (e.g. PHP.eB) have been shown to enhance brain delivery in rodents via the LY6A receptor on brain endothelial cells. Here, we create a non-invasive positron emission tomography (PET) methodology to track viruses. To provide the sensitivity required to track AAVs injected at picomolar levels, a unique multichelator construct labeled with a positron emitter (Cu-64, t = 12.7 h) is coupled to the viral capsid. We find that brain accumulation of the PHP.eB capsid 1) exceeds that reported in any previous PET study of brain uptake of targeted therapies and 2) is correlated with optical reporter gene transduction of the brain. The PHP.eB capsid brain endothelial receptor affinity is nearly 20-fold greater than that of AAV9. The results suggest that novel PET imaging techniques can be applied to inform and optimize capsid design.
腺相关病毒 (AAV) 通常是包裹在 25nm 蛋白衣壳内的单链脱氧核糖核酸 (ssDNA)。最近，组织特异性 AAV 衣壳 (例如 PHP.eB) 通过脑内皮细胞上的 LY6A 受体显示出增强啮齿动物脑内传递的能力。在这里，我们创建了一种非侵入性的正电子发射断层扫描 (PET) 方法来追踪病毒。为了提供跟踪注射在皮摩尔水平的 AAV 所需的灵敏度，将带有正电子发射体 (Cu-64，t=12.7h) 的独特多螯合剂构建体与病毒衣壳偶联。我们发现，PHP.eB 衣壳在大脑中的积累 1）超过了之前任何关于靶向治疗脑摄取的 PET 研究报告的水平，2）与脑光学报告基因转导相关。PHP.eB 衣壳脑内皮受体亲和力比 AAV9 高近 20 倍。结果表明，新的 PET 成像技术可用于为衣壳设计提供信息和优化。
