FIG. 7.

Disruption of the E7 ORF results in a cis-dependent increase in E1 expression. (A) Model illustrating E7 ORF-dependent modulation of E1 expression via a trans or cis mechanism. (B) Complementation assays monitored E1-dependent amplification in transiently transfected SCC13 cells, using HPV-16 plasmids containing E7 ORF mutants (E7−) in cis or trans by examining composite digest patterns of linearized, DpnI-resistant fragments from plasmids expressing E2 (plasmid A1 or A2) or expressing E1 (plasmid B1 or B2) via Southern blotting. Aliquots of linearized HPV-16 plasmid genomes (1 and 30 pg) were included as positive blotting controls.