Equus caballus papillomavirus-2 (EcPV-2): an infectious cause for equine genital cancer?
Authors: Scase T, Brandt S, Kainzbauer C, Sykora S, Bijmholt S, Hughes K, Sharpe S, Foote A
Journal: Equine veterinary journal
Summary
# Editorial Summary: EcPV-2 and Equine Genital Cancer Genital squamous cell carcinoma (SCC) remains a significant clinical problem in horses, yet its underlying cause has eluded researchers—prompting Scase and colleagues to investigate whether papillomavirus infection might be responsible, as it is well-established in human genital malignancies. Using rolling circle amplification and PCR analysis of genital tumour samples from horses in the UK, Australia and Austria, the research team identified and fully characterised a novel papillomavirus species designated Equus caballus papillomavirus-2 (EcPV-2), with both viral DNA and RNA confirmed present within neoplastic tissue by in situ hybridisation. Crucially, EcPV-2 was absent from histologically normal adjacent tissue, non-genital carcinomas (ocular and nasal), and smegma samples from disease-free horses, establishing tissue-specific and disease-specific association. Sequence analysis revealed variations within the E1 and E6 genes across archived tumour samples, suggesting potential heterogeneity in viral populations. These findings represent a significant breakthrough in understanding equine genital SCC aetiology and open the prospect of developing preventative vaccination strategies—a therapeutic approach that could transform management of this serious condition, mirroring the success of papillomavirus vaccination in human cervical cancer prevention.
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Practical Takeaways
- •EcPV-2 appears to be a causative agent in equine genital cancer, similar to papillomavirus's role in human cervical cancer, suggesting future vaccine development may prevent this disease
- •Veterinarians should consider papillomavirus testing when evaluating horses with genital SCC, as this may inform treatment and prevention strategies
- •Detection of EcPV-2 is specific to genital tumours and does not occur in other equine carcinomas or normal genital tissue from healthy horses, making it a potentially useful diagnostic marker
Key Findings
- •A novel papillomavirus species, EcPV-2, was identified and characterized from equine genital SCC tissue
- •EcPV-2 viral DNA and RNA were present in genital tumour samples but absent in adjacent histologically normal tissue
- •EcPV-2 DNA was not found in equine ocular or nasal carcinomas, scrotal skin, or most smegma samples from tumour-free horses
- •Sequencing revealed variations within E1 and E6 genes at DNA and predicted protein levels in archived equine genital tumours