Nucleotides 1506-1625 of bovine papillomavirus type 1 genome can enhance DNA packaging by L1/L2 capsids

We have previously described a DNA-packaging assay using bovine papillomavi rus type 1 (BPV-1) virus-like particles (VLPs) and have identified a region of the BPV genome that assists in packaging. In this study, we identify a specific BPV sequence involved in DNA packaging by BPV-1 VLPs. In the initi al screening of BPV-1 genomic sequences essential for DNA packaging, we obs erved that a plasmid with deletions between nucleotides (nt) 948 and 2113 f ailed to be packaged into BPV-1 VLPs. However, plasmids containing nt 948 t o 2113 were efficiently packaged, suggesting that this 1.2-kb fragment cont ains a packaging enhancement sequence (PES). Further mapping of the BPV-1 g enome showed that this packaging sequence lies between nt 1506 and 1625. Fu rthermore, this packaging sequence is also recognized by HPV6b VLPs, sugges ting that a common packaging mechanism may be used by the two papillomaviru s types. Given the phylogenetic difference between these two viral types, i t is likely that other papillomavirus types may also use the same packaging mechanism. Identification of the PES has allowed a minimal viral genome se quence to be used in the packaging assay, improving the usefulness of the a ssay in studying the process of papillomavirus DNA encapsidation. (C) 1999 Academic Press.