Localization of Bovine Papillomavirus Nucleic Acid in Equine Sarcoids.
Authors: Gaynor A M, Zhu K W, Dela Cruz F N, Affolter V K, Pesavento P A
Journal: Veterinary pathology
Summary
# Editorial Summary: BPV Localisation in Equine Sarcoids Bovine papillomavirus (BPV1 and BPV2) involvement in equine sarcoid development has remained frustratingly difficult to prove definitively, partly because these viruses are widespread on normal skin and in the environment. Gaynor and colleagues developed a sensitive in situ hybridisation (ISH) assay targeting viral transcripts from the E5, E6, and E7 genes, allowing direct visualisation of BPV nucleic acid within intact tissue samples. The technique detected viral material in all 18 sarcoid specimens examined whilst showing no signal in 15 non-sarcoid control samples, with 89% of cases displaying BPV nucleic acid in at least 50% of fibroblastic cell nuclei throughout the lesion; the remaining cases showed lower fibroblastic involvement but additional viral presence in epithelial structures including sebaceous glands and hair follicles. This work provides equine clinicians and pathologists with a robust diagnostic tool that moves beyond simple viral detection towards understanding *where* and *how extensively* BPV establishes itself within sarcoid tissue, potentially helping distinguish true pathogenic involvement from environmental contamination—a distinction with important implications for treatment decisions and prognosis discussions with owners.
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Practical Takeaways
- •ISH assay is a reliable diagnostic tool for confirming BPV involvement in suspected sarcoids, improving diagnostic certainty over histology alone
- •Wide distribution of viral nucleic acid throughout sarcoid lesions suggests systemic viral involvement rather than localized infection, which may inform treatment strategy selection
- •The consistent detection of BPV in sarcoids but not controls strengthens the causal link between BPV and equine sarcoids, supporting the viral origin of these neoplasms
Key Findings
- •BPV nucleic acid detected in 18/18 equine sarcoid samples using ISH assay, with none detected in 15/15 control nonsarcoid samples
- •In 89% of sarcoids (16/18), ≥50% of fibroblastic cell nuclei throughout the neoplasm contained detectable BPV hybridization
- •Viral nucleic acid localized to fibroblastic cells in most cases, with additional detection in epithelial cells of sebaceous glands, hair follicles, and epidermis in 2 cases
- •In situ hybridization targeting E5, E6, E7 genes provides superior sensitivity for direct visualization of BPV nucleic acid in routinely processed histopathologic samples