Fig. 6. Ad5-specific humoral responses limit the duration of transgene expression after Ad5 immunization.

(A) Experimental approach for evaluating the effect of Ad5-specific humoral responses on transgene expression. Sera donors were Ad5-immune (week 4 after immunization) or naïve C57BL/6 mice, and recipients were naïve A/J mice (with white coat) to allow for improved visualization of luciferase by in vivo bioluminescence. One day after passive immunization (1000 μl of sera per mouse intraperitoneally), recipient A/J mice were immunized intramuscularly with 10⁹ PFU of Ad5-luciferase. (B) Summary of transgene expression by in vivo bioluminescence imaging. Each adjacent dot represents the luciferase signal from the left and right quadriceps (adjacent dots are from the same mouse). Each quadriceps represents an independent data point because it is a separate site of immunization. (C) Representative bioluminescence images. Data are from two experiments, one with n = 4 to 5 per group and another with n = 1 per group. All data are shown. Indicated P value was determined by parametric test (unpaired t test).