FIG. 6.

(A) Human serum was administered i.v. to SCID mice, and serum was isolated at various time points. The undiluted human serum fraction was tested in vitro for the ability to inhibit Ad5-mediated luciferase gene transfer to human A549 cells (black circles). The serum fraction was subsequently diluted 10-fold in PBS (black squares) to mimic the dilution of the samples retrieved from the mice that received injections. Mouse serum was isolated at 6 h (black triangles) post-serum administration and after 48 h (black diamonds). Serum from mice that received Ad5-negative human serum served as negative controls (white circles). (B) Ad35 viruses transduce muscle in presence of human serum with NA against Ad5. Results are presented as luciferase activity in 25 μl of muscle lysates (left graph), showing that Ad5.Luc expression is largely reduced in the presence of human serum with Ad5 NA (+serum) compared to Ad5.Luc activity in mice that received human serum without Ad5 NA (−serum). This reduction is not seen in mice receiving Ad35.Luc viruses. In the graph at right the luciferase activity determined in muscle from mice that received human anti-Ad5 serum (+serum) is shown as a percentage of luciferase activity compared to that in mice that received anti-Ad5-negative serum (−serum).