The physical state of human papillomavirus 16 DNA in cervical carcinoma and cervical intraepithelial neoplasia.

Cervical carcinomas and cervical intraepithelial neoplasias (CIN) were analyzed for the presence of human papillomavirus (HPV) DNA using Southern blot hybridization. Of the five HPV types examined (HPV types 6, 11, 16, 18, and 33), HPV 16 DNA was detected most frequently. In most HPV 16-positive carcinomas examined, HPV 16 DNA was present in an integrated state in cellular DNA with or without the coexistence of episomal species. In one case, however, only episomal species were detected. Among seven cases of HPV 16-positive CIN, four contained HPV 16 DNA only in the episomal state and the rest contained HPV 16 DNA only in the integrated state, but the coexistence of both states was not found. These results suggest that the integration of HPV 16 DNA is not necessary for cells to become malignant, although it is frequently associated with malignant cells.