Two separate replication modes of the bovine papillomavirus BPV1 origin of replication that have different sensitivity to p53

We have shown previously that transient amplificational replication of reporter plasmids that carry the papillomavirus origin of replication is efficiently blocked by p53 protein in several cell lines. We demonstrate now that the replication of stably maintained episomal bovine papillomavirus BPV1 URR (upstream regulatory region) reporter plasmid is not sensitive to p53. In addition, these two replication modes—initial transient amplificational replication and stable maintenance replication of essentially the same BPV1 URR reporter plasmid—can take place in the same cells, where amplificational replication does not interfere with the stable maintenance replication. These data suggest that BPV1 replicons could follow two clearly separable replication mechanisms during initial amplification and during stable extrachromosomal maintenance.