Viral-mediated gene augmentation offers tremendous promise for the treatment of inherited retinal diseases. The development of effective gene therapy requires an understanding of the vector's tissue-specific behavior, which may vary depending on serotype, route of delivery, or target species. Using an ex vivo organotypic explant system, we previously demonstrated that retinal tropism and transduction of adeno-associated virus type 2 (AAV2) vary significantly depending on serotype in human eyes. However, the ex vivo system has limited ability to assess route of ocular delivery, and relatively little literature exists on tropic differences between serotypes and routes of delivery in vivo. In this study, we demonstrate that retinal tropism and transduction efficiency of five different AAV2 serotypes (AAV2/1, AAV2/2, AAV2/6, AAV2/8, and AAV2/9) expressing enhanced green fluorescent protein driven by a cytomegalovirus promoter vary greatly depending on serotype and route of delivery (intravitreal, subretinal, or suprachoroidal) in rats. With subretinal delivery, all serotypes successfully transduced the retinal pigmented epithelium and outer nuclear layer (ONL), with AAV2/1 displaying the highest transduction efficiency and AAV2/2 and AAV2/6 showing lower ONL transduction. There was minimal transduction of the inner retina through subretinal delivery for any serotype. Tropism by suprachoroidal delivery mirrored that of subretinal delivery for all AAV serotypes but resulted in a wider distribution and greater ONL transduction. With intravitreal delivery, retinal transduction was seen primarily in the inner retina (retinal nerve fiber, ganglion cell, and inner nuclear layers) for AAV2/1 and AAV2/6, with AAV2/6 showing the highest transduction. When compared with data from human explant models, there are substantial differences in tropism and transduction that are important to consider when using rats as preclinical models for the development of ocular gene therapies for humans.

中文翻译：

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腺相关病毒 (AAV) 的视网膜趋向性和转导因大鼠的血清型和递送途径（玻璃体内、视网膜下或脉络膜上）而异。

病毒介导的基因增强为遗传性视网膜疾病的治疗提供了巨大的希望。开发有效的基因疗法需要了解载体的组织特异性行为，这可能因血清型、递送途径或目标物种而异。使用离体器官外植体系统，我们之前证明了腺相关病毒 2 (AAV2) 的视网膜趋向性和转导因人眼中的血清型而异。然而，离体系统评估眼部递送途径的能力有限，关于血清型和体内递送途径之间的热带差异的文献相对较少. 在这项研究中，我们证明了表达由巨细胞病毒启动子驱动的增强型绿色荧光蛋白的五种不同 AAV2 血清型（AAV2/1、AAV2/2、AAV2/6、AAV2/8 和 AAV2/9）的视网膜趋向性和转导效率各不相同。很大程度上取决于大鼠的血清型和递送途径（玻璃体内、视网膜下或脉络膜上）。通过视网膜下递送，所有血清型都成功转导了视网膜色素上皮和外核层 (ONL)，其中 AAV2/1 显示出最高的转导效率，而 AAV2/2 和 AAV2/6 显示出较低的 ONL 转导。对于任何血清型，通过视网膜下递送对内视网膜的转导最小。脉络膜上递送的趋向性反映了所有 AAV 血清型的视网膜下递送的趋向性，但导致更广泛的分布和更大的 ONL 转导。对于玻璃体内给药，AAV2/1 和 AAV2/6 的视网膜转导主要出现在视网膜内层（视网膜神经纤维、神经节细胞和内核层），其中 AAV2/6 显示出最高的转导。与来自人类外植体模型的数据相比，当使用大鼠作为开发人类眼部基因疗法的临床前模型时，需要考虑的向性和转导存在重大差异。