Administration of LV-DR4/fLuc vector intravenously (i.v.) into NRG and huNRG mice and bioluminescence imaging (BLI) analyses. (A) Experimental design for testing of LV-DR4/fLuc vector in NRG (CTR: n = 3, 1 μg: n = 3, 3 μg: n = 3), and huNRG mice (CTR: n = 4, 1 μg: n = 3, 3 μg: n = 4); (B) Representative BLI pictures of NRG and huNRG mice injected i.v. with 3 μg p24 equivalents of LV-DR4/fLuc vector; (C) Quantitative BLI signal obtained by quantifying region of interest (ROI) in spleen from each mouse in NRG and huNRG mice injected i.v. with PBS (CTR), 1 μg, and 3 μg p24 equivalents of LV-DR4/fLuc vector. Dose-finding experiments. * p < 0.05, *** p < 0.001, ns: not statistically significant (t-test, unpaired).