Supplementary Figure 5: The FLPo-FRT two-component system allows sparse gene expression.

(a) Schematic of the two viral vectors used for sparse gene expression with FlpO recombinase encoded in one viral vector and a transgene flanked by FRT sites on a second viral vector. In the basal state, the XFP is expressed in a double inverted orientation (fDIO) and upon the presence of FLPo is inverted into the orientation in line with the CAG promoter for expression. (b) Representative images of native mNeonGreen fluorescence two weeks after intravenous administration of ssAAV-PHP.B:CAG-fDIO-mNeonGreen at 1 × 10¹² vg/mouse together with the indicated dose of ssAAV-PHP.B:EF1α-FLPo. (c) Magnified images of the cortex, striatum, and cerebellum. Scale bars are 1 mm (b) and 50 μm (c).