Figure 2. LV-RPE65 injected at P5 protects cones up to 4 months post injection.

(A–D) In wild type mice, S-opsin (red) and GNAT2 (green) expressions are localized to outer segments. (E,F) In 4-month-old untreated Rpe65^R91W/R91W mice, S-opsin is highly mislocalized in the cone photoreceptors and the labeling shows distinctly cell bodies (in red, arrow) and feet (in red, arrowhead) of cones. (G,H) At the same age, the cone transducin labeling (GNAT2 in green) is strongly reduced with only minor signals in some tips of shortened outer segments (star). (I,J) Similarly to untreated animals, LV-GFP-injected Rpe65^R91W/R91W mice show reduced and mislocalized expression of S-opsin (red, arrow), even in the region of GFP expression (green). (K,L) The strong reduction of GNAT2 labeling (red, star) is also evident in the LV-GFP-treated region (GFP in green). (M,N) On the contrary, after LV-RPE65 injection at P5, in the region of RPE65 expression (green), strong S-opsin expression is observed in cone outer segments (red) while in the region devoid of WT RPE65 expression there is evidence of S-opsin mislocalization to the cell body (arrow) and synaptic termini (arrowhead). (O,P) RPE65 gene transfer also rescues GNAT2 expression (green) in cone outer segments in the region of RPE65 expression (red). GNAT2: cone-specific transducin α-subunit; S-opsin: short wavelength cone opsin; the scale bar indicated in A represents 50 µm for A-P.