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

This research article investigates the origin of equine sarcoid, a common type of skin cancer in horses, studying their morphology and the molecular mechanisms involved. Identifying Bovine Papillomavirus (BPV) as a major contributor to the disease, the study also confirms that sarcoids occur due to a nonproductive infection in a nonpermissive host with BPV.

Study Process and Findings

• The research was conducted on 932 equine skin lesions, out of which 421 were identified as sarcoids which makes up roughly 45% of all studied lesions.
• Main areas where these sarcoids were found include the ventral body regions, head, neck, and areas with thin skin.
• Different types of sarcoids were identified with the fibroblastic type being most common, mixed type less frequent, and verrucous type being the least diagnosed.

Identification of Bovine Papillomavirus (BPV)

• The study utilized polymerase chain reaction (PCR), a common method in molecular biology to amplify specific DNA sequences, to detect BPV-DNA.
• A specific oligonucleotide primer that is located in the E5-open reading frame was used for the PCR.
• The differentiation between DNA of two types of BPV (BPV1 and BPV2) is achieved by digestion with restriction endonucleases, which are enzymes that cut DNA at particular sequences.
• Out of 108 sarcoids, BPV-DNA was identified in 97 samples with most of them showing a BPV 1 specific pattern in restriction enzyme analysis.

Assertion of BPV as Etiology

• To visualize the localization of BPV within sarcoids, nonradioactive in situ hybridization was performed on 20 sarcoids.
• The hybridization signal, which corresponds to the presence of BPV-DNA, was mostly found in the nuclei of fibroblast-like tumor cells, particularly at the dermo-epidermal junction, suggesting that BPV infects these particular cells to drive tumorigenesis.
• No evidence of BPV-DNA was found in epidermal cells which only helps in asserting the relationship between sarcoids and BPV infection.

Conclusion

• The findings of the study suggest equine sarcoids result from a nonproductive infection with BPV in a nonpermissive host, confirming the assumption that BPV is a major etiological factor in the formation of these tumors.