Equine connective tissue tumors contain unintegrated bovine papilloma virus DNA

Abstract

Bovine papilloma virus (BPV) appears to be the etiological agent of common equine connective tissue tumors. The physical state of the viral DNA within such tumors was investigated and there was no indication for integration into the host genome. The BPV genomes were present as free circular episomes. Two equine sarcoids contained multiple copies of free circular BPV type 1 (BPV-1) DNA. When the tumors were digested with several single-cut restriction enzymes, there were only form III BPV-1 DNA sequences present in the DNA derived from the tumors and no integrated BPV-1 DNA sequences could be revealed. One sarcoid contained, apart from wild-type BPV-1 DNA, a class of smaller BPV-1 circular DNA molecules bearing a deletion of approximately 9% of the BPV-1 genome. This deletion is located in the physical map between the relative units 0-0.32.