Fig. 4.

PCR for E2 and E6 genes of HPV-16. DNA extracted from oropharynx tumours were amplified with specific primers for the E2 and E6 genes of HPV 16. Note that in lane 11, the E2-amplified band is lacking indication of viral integration; in lane 1, the presence of both E2 and E6 bands indicates the presence of episomal virus like in the W12 control, whereas in line 3 the higher intensity of E6 band suggests (thereafter it was confirmed by E2/E6 ratio) the simultaneous presence of integrated and episomal forms. W12 is a cell line containing episomal HPV-16 DNA. M8 = DNA Molecular Weight Marker VIII (Roche); DNA fragment length in bp is indicated. Neg = a control without DNA