Viral plaque formation on U251 cells. Monolayers of U251 were infected with RL-07 or wtHAdV-5 with a MOI of 2.2 × 10-5 and 6 × 10-5 respectively, and overlaid with 0.5% agar in F15 media supplemented with 2% Horse serum. Ten days p.i. the agar was removed and cells were stained with 0.5% crystal violet solution. (A) Photograph of plaques of wtHAdV-5 and RL-07 on U251 monolayer (B) Relative plaque surface of 10 plaques. *-statistical significance; unpaired, two-sided, t-test, p < 0.01. wtHAdV-5 - black closed triangles; RL-07 - grey closed triangles.