Genomic organization of human papillomavirus type 18 in cervical cancer specimens

It has been reported that cervical cancers positive for human papillomavirus (HPV) 18 have a poorer prognosis than those with other HPV types. To gain a better understanding of the aggressive character of HPV 18-positive cancers, we examined the difference in genomic organization between HPV 18 and HPV 16 harbored in cervical cancers. We amplified E1 and E2 genes from 9 HPV 18-positive and 31 HPV 16-positive cervical cancers by polymerase chain reaction (PCR). At least one of the two early genes was missing in 3 out of 9 HPV 18-positive cancers, while both PCRs were positive in all 31 HPV 16-positive cancers (P < 0.05). We then analyzed the 9 HPV 18-positive cancers by 15 contiguous polymerase chain reactions covering collectively the whole HPV 18 genome. In addition to the three with a deletion of the E1 or E2 gene, one had a deletion in the E5 and L2 genes and one had an insertion in the long control region. The frequent alterations in genomic organization, especially preferential deletion of the E1 or E2 gene, may be related to the more aggressive properties of HPV 18-positive cervical cancers.