Presence of human papillomavirus type 18 DNA in vulvar carcinomas and its integration into the cell genome.

We have screened 78 genital tract tumours from Italian female patients for the presence of human papillomavirus type 16 (HPV-16) and HPV-18 DNA. Dot and Southern blot hybridization experiments revealed that DNA sequences of HPV-16 and/or HPV-18 are present in 66% of tumour samples. HPV-18 was detected in 80% of vulvar carcinomas. In these tumours the integration of HPV-18 DNA seems to occur in the E1/E2 region of the virus genome with long deletions in almost all samples. The invariable retention of the non-coding region and the E6/E7 open reading frames suggests that the integration event and the possible expression of these sequences could play a role in some stages of cellular transformation.