The invention provides hybrid and recombinant phagemid vectors for expressing a transgene in a target cell transduced with the vector. A recombinant phagemid particle comprises at least one transgene expression cassette which encodes an agent which exerts a biological effect on the target cell, characterised in that the phagemid particle comprises a genome which lacks at least 50% of its bacteriophage genome. The invention extends to the use of such phagemid expression systems as a research tool, and for the delivery of transgenes in a variety of gene therapy applications, DNA and/or peptide vaccine delivery and imaging techniques. The invention extends to in vitro, in vivo or in situ methods for producing viral vectors, such as recombinant adeno-associated viruses (rAAV) or lentivirus vectors (rLV), and to genetic constructs used in such methods.

Compositions and methods are provided for treating ocular disorders in a subject are provided. In one aspect, an adeno-associated viral vector is provided which includes a nucleic acid molecule comprising a sequence encoding CNGA3. In another aspect, an adeno-associated viral vector is provided which includes a nucleic acid molecule comprising a sequence encoding CNGB3. In another aspect, an adeno-associated viral vector is provided which includes a nucleic acid molecule comprising a sequence encoding REP-1. In desired embodiments, the subject is human, cat, dog, sheep, or non-human primate.