SUMMARY

The pattern of human papillomavirus type 16 (HPV-16) integration was studied in 23 invasive carcinomas of the cervix using subgenomic probes. Seventeen tumours contained integrated HPV-16 and in 13 of these there was evidence of disruption within the El-E2 open reading frames (ORFs). In all cases the upstream regulatory region (URR)-E6-E70RFs was maintained intact. Two independently derived tumours were infected with episomal wild-type HPV-16 and an episomal variant of HPV-16 containing a 325 bp deletion within the URR (positions 7598 to 17) and a point mutation at position 20 (A to C). This is the first report of a variant HPV-16 which is likely to be both defective and transmissible. Loss of E2 expression and deletion of a large portion of the URR may be two of the mechanisms leading to altered HPV-16 early gene expression i cervical tumours. The prevalence of human papillomavirus (HPV) infection in the normal female population suggests that HPV may be a relatively ubiquitous agent (de ViUiers et al., 1987). This would imply that secondary events following HPV infection, probably combined with cellular factors, are of importance in the development of cervical neoplasia. One of the secondary events tha