Evidence for a switch in the mode of human papillomavirus type 16 DNA replication during the viral life cycle

J Virol. 1997 Oct;71(10):7167-79. doi: 10.1128/JVI.71.10.7167-7179.1997.


The study of human papillomavirus type 16 (HPV-16) replication has been impaired because of the lack of a cell culture system that stably maintains viral replication. Recently, cervical epithelial cell populations that stably maintain HPV-16 replicons at a copy number of approximately 1,000 per cell were derived from an HPV-16-infected patient (W12 cell clone 20863 [W12-E cells]). We used neutral/neutral and neutral/alkaline two-dimensional gel electrophoretic techniques to characterize HPV-16 DNA replication in these cells. When W12-E cells were maintained in an undifferentiated state mimicking the nonproductive stage of the life cycle, HPV-16 DNA was found to replicate primarily by theta structures in a bidirectional manner. The initiation site of HPV-16 DNA replication was mapped to approximately nucleotide 100, and the termination site was mapped to between nucleotides 3398 and 5990. To study the productive stage of HPV-16 DNA replication, W12-E cells were grown under culture conditions that promote differentiation of epithelial cell types. Under these conditions, where virus-like particles were detected, the mode of viral DNA replication changed from theta structure to what is apparently a rolling circle mode. Additionally, CIN 612-9E cells, which were derived from an HPV-31-infected patient and harbor HPV-31 extrachromosomally, exhibited the same switch in the mode of DNA replication upon induction of differentiation. These data argue that a fundamental switch in the mechanism of viral DNA replication occurs during the life cycle of the papillomavirus.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Cell Differentiation
  • Cell Nucleus / ultrastructure
  • Cervix Uteri / virology
  • Clone Cells
  • DNA Replication*
  • DNA, Viral / biosynthesis*
  • DNA, Viral / isolation & purification
  • Epithelial Cells
  • Epithelium / ultrastructure
  • Epithelium / virology
  • Female
  • Humans
  • Kinetics
  • Models, Biological
  • Papillomaviridae / genetics
  • Papillomaviridae / physiology*
  • Terminator Regions, Genetic


  • DNA, Viral