Fig. 1.

Gene transfer and expression by HPV16 pseudovirions. The histogram shows SEAP activity levels in cell culture supernatants 48 h after treating 293T cells with the stated dilutions of virus particles purified by Optiprep gradient fractionation from cells mock-transfected or transfected with the indicated combinations of reporter plasmid pSEAP and independent expression plasmids for HPV16 capsid proteins L1 and L2. For the direct transfection positive control (second bar from the right), SEAP activity was measured directly on 293T cells transfected with 1 μg of pSEAP DNA.