Induced leukocyte recruitment via the activated tumor vasculature in GLV-1h68 infected tumors. GI-101A tumor-bearing mice were i.v. injected with 5 × 106 pfu of GLV-1h68 and tumors were harvested 42 days p.i.. (a, b) Whole tumor cross-sections of GLV-1h68-infected tumors (a) and control GI-101A tumors (b) were labelled with anti-MHCII antibody to visualize the recruitment of MHCII-positive leukocytes. (c) Confocal image of GLV-1h68-colonized tumors revealed accumulation of CD45-positive leukocytes around viral patches. (d, e) Confocal images showed intense interaction of CD45-positive (d) and MHCII-positive leukocytes (e) with the CD31-positive tumor vasculature. Immune cells were labelled with anti-MHCII antibody (red; a, b, e) or anti-CD45 antibody (red; c, d); nuclei were visualized using Hoechst (blue in a, b; orange in c, d, e), tumor vasculature was labelled with anti-CD31 antibody (blue) and viral infection was indicated by GFP fluorescence (green). All images are representative examples. Scale bars represent 1 mm (a, b), 300 μm (c-e).