CONDITIONAL REQUIREMENT FOR SEQUENCES DISTINCT FROM THE REPLICATION ORIGIN DURING EPISOMAL ESTABLISHMENT OF THE BPV1 GENOME

Removal from BPV1 DNA of a short segment (nt. 4786-5045) that contains several protein binding sites and is required for efficient replicati on in short term assays prevents its autonomous maintenance in cell li nes established by selection in G418 medium after cotransfer of neo(r) . In contrast, transformed cell lines established from foci, which exp ress the viral genes at higher levels, maintain extrachromosomal copie s of the deleted DNA. Two modes of maintenance of the viral genome are thus distinguished by their requirement for sequences in this region, (C) 1996 Academic Press, Inc.