Figure 1.

Tattooing of rSFV replicon particles results in high transgene expression. Luciferase expression by SFVLuc was determined in vivo with bioluminescence imaging using a CCD camera. Mice were tattooed (a) or injected intramuscularly (b) with 10⁷ i.u. of SFVLuc. After 6 h, images with an integration time 30 s were taken. Blue colors represent the least and red colors represent the most intense light intensity. Two representative mice for each group are shown. Immediately after in vivo measurements, animals were sacrificed and muscles from the intramuscularly treated group or skin from the tattooed group and draining inguinal lymph nodes were isolated for ex vivo luciferase expression. Luciferase expression is shown as expression per mg organ (c) or per total organ (d) (n = 4). Data of a representative experiment out of two are shown. * p < 0.05. Mice were intramuscularly injected with 10⁸ i.u. of SFV-EGFP (e) or PBS (f). After 24 h, skin and muscle from the site of administration were excised and analyzed by immunofluorescence staining. For immunofluorescent staining, muscle tissue expressing EGFP were analyzed using anti-GFP antibody (green). Cell nuclei were detected using DAPI (blue) (magnification 40×). A representative image for each group is shown.