The present invention relates to viral vectors that are capable of delivering a heterologous gene to the retina and in particular delivering RLBP1 to RPE and Müller cells of the retina. The invention also relates nucleic acids useful for producing viral vectors, compositions comprising the viral vectors and uses of the compositions and viral vectors. The invention also relates to methods of delivering and/or expressing a heterologous gene to the retina, improving the rate of dark adaption in a subject and treating RLBP1-associated retinal dystrophy.本發明係關於能夠傳遞異源基因至視網膜且詳言之傳遞RLBP1至視網膜之RPE及穆勒細胞(Müller cell)之病毒載體。本發明亦關於適用於產生病毒載體之核酸、包含該等病毒載體之組合物及該等組合物及病毒載體之用途。本發明亦關於傳遞及/或表現異源基因至視網膜、提高個體之暗適應速率及治療RLBP1相關視網膜營養性萎縮之方法。