[Morphologic and molecular biologic studies of the etiology of equine sarcoid].

From 932 equine skin lesions 421 were diagnosed as sarcoids (about 45%). The most common locations were the ventral body regions, head, neck and sites of thin skin. Most often the fibroblastic type, less frequently the mixed type and most infrequent the verrucous type of sarcoid were diagnosed. Detection of BPV-DNA was performed by polymerase chain reaction (PCR) using an oligonucleotide primer pair located in the E5-open reading frame. DNA of BPV 1 and BPV 2 could be differentiated by digestion with restriction endonucleases. In 97 out of 108 sarcoids BPV-DNA was detected by PCR. Most samples showed a BPV 1 specific pattern in restriction enzyme analysis. Nonradioactive in situ hybridization was carried out on 20 sarcoids. The hybridization signal was associated with the nuclei of fibroblast-like tumor cells, predominantly at the dermo-epidermal junction. In epidermal cells, BPV-DNA could not be detected. This study confirms the opinion that sarcoids are the result of a nonproductive infection in an alien, nonpermissive host with BPV.