Fig 6. Synergistic inhibitory effect between Camptothecin (CPT) and compounds identified in the HT screen on the initial amplification of the HPV18 genome.

U2OS-EBNA1 cells were transfected with HPV18 wt and oriP plasmids and grown in the presence of the indicated concentrations of compounds alone or together with 2 nM CPT for 5 days. Genomic DNA was extracted, linearized and digested with DpnI. Both HPV18 and oriP replication signals were detected with Southern blot and quantified using a phosphoimager. Compounds 9782, 88915, 109128 and 305831 showed modest synergistic inhibition together with CPT (panels A, C, D and E), whereas compound 82269 did not (panel B). Error bars represent standard deviations from at least three independent experiments. Lanes 15 and 16 are size markers for HPV18 and oriP.