FIG 3.

HPV18 central URR element Reg2 alone is necessary but insufficient for replicon maintenance. (A) Diagram of HPV18 replicons. (B) Keratinocyte colonies arising from continuous G418 selection were stained with methylene blue approximately 14 days posttransfection. (C) DNA collected from five passages of transfected cells was analyzed by Southern blotting as described in Fig. 2C. An asterisk marks cellular DNA hybridizing with the beta-globin polyA region present in the radioactive CpGneo vector probe. The monomeric, supercoiled form (s/c) of the replicon is indicated. (D) HPV18 genome (left) and replicon (right) copy numbers were measured by qPCR. Error bars represent standard deviation. The data shown are representative (panels B and C) or an average of two biological replicates (panel D).