Molecular Detection of Equus caballus Papillomavirus Type 2 in Genital Swabs From Healthy Horses in the Republic of Korea.
Authors: Lee Sang-Kyu, Lee Jung Keun, Lee Inhyung
Journal: Journal of equine veterinary science
Summary
Equus caballus papillomavirus type 2 (EcPV-2) poses a significant threat to equine genital health, driving the development of penile papillomas, intraepithelial neoplasia, and squamous cell carcinomas that rarely regress spontaneously and can result in substantial clinical and economic consequences. Lee and colleagues examined 797 genital swabs from Korean Thoroughbreds (35 stallions and 762 mares) using PCR-based detection of the E1 gene, with confirmatory sequencing of E6 amplicons and phylogenetic characterisation of positive isolates. EcPV-2 DNA was detected in only 1% of mares (8/762) with no detection in stallions, though notably all positive mares had been imported from the United States, suggesting either exposure during transit or introduction via breeding stock rather than endemic circulation. Phylogenetic analysis revealed three distinct subdivisions clustering with European strains, plus three isolates on separate branches, indicating genetic diversity within the Korean population. These findings highlight the importance of screening imported breeding stock for EcPV-2 prior to introduction, as asymptomatic carrier mares may introduce latent infection; practitioners should maintain awareness of this virus as a differential diagnosis in any case of genital neoplasia, particularly in animals with import history.
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Practical Takeaways
- •Clinically healthy mares, particularly those imported from the United States, may carry EcPV-2 DNA asymptomatically and represent a potential reservoir for transmission
- •Genital screening using PCR-based detection of E1 and E6 genes can identify EcPV-2 carriers before clinical signs of neoplasia develop, enabling early intervention
- •The virus's documented prevalence in asymptomatic animals and its potential for malignant transformation to squamous cell carcinoma justifies inclusion in pre-breeding health assessments for imported horses
Key Findings
- •EcPV-2 DNA was detected in 1% (8/762) of mare genital swabs but in none of the 35 stallion swabs tested
- •All EcPV-2-positive mares had been imported from the United States, suggesting geographic and importation-related prevalence patterns
- •Phylogenetic analysis of E6 gene sequences revealed three subdivisions related to European strains with some isolates on separate branches, indicating genetic variability in EcPV-2