Initial detection of a circular genome deletion in a naturally bovine papillomavirus-infected sample.

Bovine papillomavirus type 12 (BPV-12) was recently identified in epithelial papillomas on the cattle tongue in our previous study. Along with the full-length genome, one deleted circular genome, named BPV-12-del, was detected in the same papilloma lesion. BPV-12-del is 3363 base pairs in length, and a total of 3,384 base pairs, including E1, E2 and E4 genes and partial E7 and L2 ORFs, were deleted compared with the complete genome. Real-time PCR results showed that the percentage of BPV-12-del was 42% of the total genomes in the sample. Southern Blot analysis also confirmed the presence of the deleted genome. This is the first report describing a circular genome deletion detected in a naturally BPV-infected sample.