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.