Equine papillomavirus type 2: An equine equivalent to human papillomavirus 16?
Authors: Sykora S, Jindra C, Hofer M, Steinborn R, Brandt S
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary Equine papillomavirus type 2 (EcPV2) is increasingly implicated in squamous cell carcinomas affecting genital tissues, yet its role in head and neck tumours remains unclear; this 2017 study investigated whether EcPV2 might function similarly to human papillomavirus 16 (a known carcinogen in human head and neck cancers) by screening 15 head SCC samples using PCR techniques targeting multiple viral genes and examining the physical form of viral DNA across tumour types. Researchers detected EcPV2 in 27% of head tumours, along with novel genetic variants, and critically found that approximately half of all tested samples contained intact viral particles, with smegma (preputial secretions) harbouring substantially higher viral loads (up to 854,000 copies per cell) compared to tumour tissue (fewer than 25 copies per cell). The E6:E2 copy ratios (ranging from 0.88 to 4.12), although not statistically significant, suggested potential viral integration into the host genome—a hallmark mechanism of papillomavirus-driven malignancy in human studies. For equine practitioners, these findings highlight preputial secretions as a probable viral reservoir and transmission source, supporting the case for EcPV2 screening in head SCC cases and suggesting that management strategies targeting viral load reduction (such as preputial hygiene protocols) may warrant investigation as preventive measures, particularly in stallions and geldings with genital SCC history.
Read the full abstract on PubMed
Practical Takeaways
- •Screen horses with head squamous cell carcinomas for EcPV2 as part of diagnostic workup, as approximately 27% may be EcPV2-positive
- •Consider smegma as a significant reservoir for EcPV2 transmission; implement biosecurity measures and hygiene protocols for horses with genital lesions or carcinomas
- •Monitor horses with known EcPV2 infection for development of squamous cell carcinomas in both genital and head regions, similar to HPV-16's role in human malignancies
Key Findings
- •4 of 15 (26.7%) head squamous cell carcinomas tested positive for EcPV2 DNA with known or novel genetic variants
- •51% of tested extracts (18 of 35) harboured EcPV2 virions as detected by immunocapture PCR, with smegma serving as a rich viral reservoir
- •Head squamous cell carcinomas contained significantly lower viral DNA amounts (<1-25 copies/cell) compared to genital tumours and smegma samples (up to 8.54×10⁵ copies/cell)
- •Majority of samples showed higher E6 than E2 DNA copy ratios (0.88-4.12), suggesting possible viral integration into host genome