Representative Southern analysis of transiently replicating HPV31 in SCC-13 cells. SCC-13 cells were transfected with religated HPV31-wt, -BS1, -BS2, -BS3, or -BS4 or genomes that contained a disrupted E1 (E1N-TTL) or E2 (E2N-TTL) gene. Low-molecular weight DNA was isolated 120 h posttransfection, digested with BanII and DpnI, and analyzed by Southern analysis using a full-length HPV31 probe. The marker lane (M) contains 100 pg of EcoRI-linearized HPV31 DNA.