RDS expression and localization to the distal connecting cilium in the mouse rod photoreceptor cell begin around postnatal day 5 (P5) [26], [32] (i.e., before OS formation), a time that precedes the onset of retinal degeneration in the rds model. Hence, we selected P5 as the physiologically appropriate developmental stage for therapeutic intervention. Two vectors were generated, each expressing the full-length cDNA of normal mouse peripherin/rds (NMP), one under the control of the ubiquitously expressed chicken beta-actin promoter (CBA), and the other employing the well characterized photoreceptor-specific promoter for the human interphotoreceptor retinoid-binding protein (IRBP) [33]. Acetate compacted nanoparticles containing the vectors (Figure S1) or controls were injected subretinally into rds+/− mice at P5 and followed for up to four months. The controls chosen for this study were saline (vehicle) and uncompacted plasmid DNA (called “naked DNA”) carrying the same therapeutic transgene (CBA-NMP or IRBP-NMP).