Figure 6

HPV11 E1 expression from E1 plasmids and transient replication of the URR-plasmid in the presence of the E1 and E2 proteins. (A, B) Detection of the HA-epitope tagged HPV11 E1 protein from transiently transfected U2OS cells. The cells were transfected with 1-5000 ng of different HPV11 E1 expression plasmids (indicated at the top of the figure). Western blot analysis was performed at the 24 h time point to detect the HPV11 E1 protein (A) and the cellular marker α-tubulin (B). (C) The HPV11 E1 and E2 proteins initiated DNA replication from the episomal HPV11 URR plasmid in transiently transfected U2OS cells. U2OS cells were co-transfected with 100 ng of the HPV11 URR plasmid, 100 ng of E2 and 1-5000 ng of different E1 expression plasmids. Extrachromosomal DNA was extracted at 24 and 48 h post-transfection via Hirt lysis, and ½ of each sample was analyzed as indicated in Figure 1A. The replication signal was detected with a radiolabelled HPV11 URR specific probe. Mock-transfected U2OS cells were used as a negative control (lane 27), and 200 pg of the linearized HPV11 URR plasmid (lane 28) was used as a size marker. The linear HPV11 URR and DpnI fragments are indicated with arrows.