Ad5 vectors capsid-displaying retro-DAF complement inhibitor do not suffer from significant thrombocytopenia, liver damage, and proinflammatory leukocytes infiltration to the livers, toxicities typically triggered by conventional Ad vectors in C57BL/6 mice. (A) C57BL/6 WT and C3-KO mice (n = 4 for all groups) were intravenously injected with 0.75 × 10¹¹ vp/mouse or 2 × 10¹¹ vp/mouse of Ad5-based control and experimental vectors. Platelets enumerations were performed at 24 and 72 hours after injection as described in “Platelet enumeration.” The bars represent mean ± SD. Statistical analysis was completed with the use of 1-way analysis of variance with a Student-Newman-Keuls post hoc test, P < .05 was deemed a statistically significant difference. Values statistically different from those in WT_Mock–injected animals, *P < .05, **P < .001; statistically different values in WT_Ad5-GFP-IX-dDAF_REO and C3-KO_Ad5-GFP groups compared with WT_Ad5-GFP and WT_Ad5-IX-dGFP groups at the same time point, #P < .05, ##P < .001. Note that the normal range levels were adapted from studies at The Jackson Laboratories on C57BL/6 mice (http://phenome.jax.org/db/qp?rtn = views/measplot&brieflook = 6219). (B) ALT activity was determined at 72 hours after injection from C57BL/6 WT and C3-KO mice, injected with PBS (Mock) or different Ad5 vectors; Mock-injected animals (n = 3), for Ad5-injected mice (n = 4). Statistical analysis was completed with the use of 1-way analysis of variance with a Student-Newman-Keuls post hoc test; P < .05 was deemed a statistically significant difference. No significant differences were detected. (C) Wild-type (WT) and C3-KO mice injections (n = 4 for all groups) and morphometric evaluation of liver sections were performed as described in “Hemotoxylin and eosin staining.” Representative sections from each treated animal were analyzed, scored, and averaged for the levels of portal, periportal, and lobular inflammation, as described in “Hemotoxylin and eosin staining.” The sum of averages for each category was computed to obtain a total inflammation index score. The error bars represent ± SD. Statistical analysis was completed with the use of 1-way analysis of variance with a Student-Newman-Keuls post hoc test; P < .05 was deemed a statistically significant difference. No significant differences were detected between virus-injected groups.