Local hF.IX expression and CD8 infiltration in HB mice. Skeletal muscle from HB mice injected i.m. with 1011 vg ss or scAAV1 (n = 4/group) was harvested, cryosectioned, and stained for hF.IX (red) and CD8 (green). Nuclei were visualized with DAPI (blue). Two weeks post-injection, tissue was analyzed from mice injected with ssAAV1 (A-B) or scAAV1 (E-F). After four weeks, skeletal muscle was stained from mice injected with ssAAV1 (C-D) or scAAV1 (G-H). Representative images from two mice are shown for each condition. The scale bar represents 100 μm. Results are representative of at least two independent experiments.