Gene augmentation therapy based on subretinal delivery of adeno-associated viral (AAV) vectors is proving to be highly efficient in treating several inherited retinal degenerations. However, due to potential complications and drawbacks posed by subretinal injections, there is a great impetus to find alternative methods of delivering the desired genetic inserts to the retina. One such method is an intravitreal delivery of the vector. Our aim was to evaluate the efficacy of two capsid-modified vectors that are less susceptible to cellular degradation, AAV8 (doubleY-F) and AAV2 (quadY-F+T-V), as well as a third, chimeric vector AAV[max], to transduce photoreceptor cells following intravitreal injection in sheep. We further tested whether saturation of inner limiting membrane (ILM) viral binding sites using a nonmodified vector, before the intravitreal injection, would enhance the efficacy of photoreceptor transduction. Only AAV[max] resulted in moderate photoreceptor transduction following intravitreal injection. Intravitreal injection of the two other vectors did not result in photoreceptor transduction nor did the saturation of the ILM before the intravitreal injection. However, two of the vectors efficiently transduced photoreceptor cells following subretinal injection in positive control eyes. Previous trials with the same vectors in both murine and canine models resulted in robust and moderate transduction efficacy, respectively, of photoreceptors following intravitreal delivery, demonstrating the importance of utilizing as many animal models as possible when evaluating new strategies for retinal gene therapy. The successful photoreceptor transduction of AAV[max] injected intravitreally makes it a potential candidate for intravitreal delivery, but further trials are warranted to determine whether the transduction efficacy is sufficient for a clinical outcome.

中文翻译：

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羊玻璃体内和视网膜下递送后衣壳修饰的腺相关病毒载体的光感受器转导功效的评估。

基于腺相关病毒 (AAV) 载体的视网膜下递送的基因增强疗法被证明在治疗几种遗传性视网膜变性方面非常有效。然而，由于视网膜下注射带来的潜在并发症和缺点，寻找将所需基因插入物输送到视网膜的替代方法有很大的推动力。一种这样的方法是载体的玻璃体内递送。我们的目的是评估两种不易受细胞降解影响的衣壳修饰载体 AAV8 (doubleY-F) 和 AAV2 (quadY-F+TV) 以及第三种嵌合载体 AAV[max] 的功效，在羊玻璃体内注射后转导感光细胞。我们进一步测试了使用未修饰载体的内界膜 (ILM) 病毒结合位点是否饱和，在玻璃体内注射前，会增强光感受器转导的功效。只有 AAV[max] 导致玻璃体内注射后中度光感受器转导。玻璃体内注射两种其他载体不会导致光感受器转导，也不会导致玻璃体内注射前 ILM 的饱和。然而，在阳性对照眼中视网膜下注射后，两种载体有效地转导感光细胞。先前在小鼠和犬模型中使用相同载体的试验分别导致玻璃体内递送后光感受器的稳健和中等转导功效，证明在评估视网膜基因治疗的新策略时使用尽可能多的动物模型的重要性。