Localization of neonatal transduction in murine tissues. FIV vectors expressing the LacZ gene were injected into neonatal mice. Three weeks post-injection, organs were removed and cryosectioned (8 μm). 4X and 20X magnification images are shown for FIV-GP64 transduced hearts (A-B) and livers (G-H) following X-gal staining. Similar images are displayed for FIV-L260F transduced hearts (C-D) and livers (I-J) and FIV-WE54 transduced hearts (E-F) and livers (K-L). Spleen and kidneys of vector-transduced animals were negative. Slides were counterstained with nuclear fast red. Scale bar in A is 500 μm; B is 200 μm. n = 3.