Fig. 3: Engineering Env by rational peptide insertion for enhanced brain targeting and liver detargeting.

a Ai9 mice were intracerebroventricularly injected with 3 ×10¹⁰ gc Cre mRNA containing VLP SFV-Env, and tdTomato signal in the brain was assessed two weeks after administration. Immunofluorescence staining for evaluation of tdTomato (green) signals in the brain. DAPI (blue) was used for nuclear staining (whole brain section: scale bar = 800 μm; magnified region: scale bar = 100 μm). b Ai9 mice were intravenously injected with 1 ×10¹² gc Cre mRNA containing SFV-Env or PBS, and tdTomato signals in the liver was examined two weeks after administration. Immunofluorescence staining for evaluation of tdTomato (green) signals in the liver. DAPI (blue) was used for nuclear staining (scale bar = 50 μm). c The structure of Env E1 (pine green) binding with VLDLR (violet). K345 and K347 of E1 were shown in wheat and D135 and D137 of VLDLR were shown in purple blue (PDB: 8IHP). d C57 mice were intravenously injected with 1 ×10¹² gc luciferase mRNA containing original VLP (SFV-Env) or engineered VLP (Env-P11). Four animals per group. e Animals in images from left to right: one background mouse and four injected mice. The dorsal views of in vivo luminescence imaging for liver targeting efficiency at various times post-injection. The ventral views of in vivo bioluminescence imaging for brain targeting efficiency at various times post-injection. The rainbow images showed the relative levels of luminescence ranging from high (red) to low (blue). Quantification of bioluminescence in the f liver (***P = 0.0005 at 8 h and ****P < 0.0001 at 2 h, 4 h, and 24 h) and g brain (*P = 0.0151 at 24 h and ****P < 0.0001 at 4 h, 6 h, and 8 h) for SFV-Env (black) and Env-P11 (pink). Error bars represented the mean with standard deviation (SD) of four animals. Statistical analyses were performed using two-way ANOVA with Šidák’s multiple comparison test. Source data are provided as a Source Data file.