Researchers have uncovered the presence of ovine papillomavirus (OaPV) DNA in the vaginal swabs of healthy mares, raising new concerns regarding equine reproductive health. A study conducted by scientists at the National Reference Center for Veterinary and Comparative Oncology (CEROVEC) in Genoa, Italy, revealed that a notable percentage of the vaginal virobiota in asymptomatic mares contained these viruses, which are known to be associated with tumors in sheep.
Published on March 22, 2025, in Scientific Reports, the study aimed to investigate the potential harboring of OaPV types in the equine vaginal environment using two highly sensitive molecular detection techniques: digital droplet polymerase chain reaction (ddPCR) and real-time quantitative PCR (qPCR). Out of 94 vaginal swab samples collected, ddPCR detected OaPV DNA in 25 samples, approximately 26.6%, while qPCR reported detection in only 11.7% (13 swabs). These differences were statistically significant, highlighting the superior sensitivity of ddPCR over traditional methods.
Among the detected strains, OaPV1 was predominant, found in 92% of the OaPV-infected swabs through ddPCR; qPCR only identified OaPV1 in 44% of the samples. Additionally, OaPV3 was noted in 8% of the cases analyzed by both methods. This study marks the first instance of OaPV DNA being reported in the vaginal swabs of healthy mares, drawing attention to the potential implications for equine reproduction.
Currently, the implications of OaPVs in mares are not fully understood. The ability of these viruses to infect and establish themselves in the competitive environment of the vaginal microbiome could signal a new avenue of concern for equine reproductive efficiency, especially considering the possible association between papillomavirus infections and reproductive disorders in other species.
The methodology applied in this study showcased the advanced capabilities of ddPCR, an improved form of PCR that can detect low levels of nucleic acids that traditional PCR methods might miss. This was underscored by the significant increase in detection rates of OaPVs with ddPCR, enabling a better understanding of viral loads that could impact reproductive outcomes.
The findings raise critical questions about the role of these viral agents, not only in equine health but also their potential insights into broader epidemiological trends that may affect livestock species. As the authors noted, "ddPCR proved to be an accurate and sensitive diagnostic tool as it significantly increases the detection of OaPVs with low viral abundance." Thus, elevating the standard for detection methods presents an opportunity to explore how these viruses might influence reproductive performance and health in mares.
Going forward, it is essential for veterinary professionals and researchers to examine the implications of OaPVs on fertility in equines further. This includes understanding their transmission routes, potential oncogenic effects, and any links they may have to reproductive disorders. The presented study paves the way for additional research into the molecular epidemiology of OaPVs in equine populations, potentially enhancing our strategies for managing reproductive health in horses.
In summary, the presence of OaPV DNA in vaginal swabs of healthy mares introduces a novel concern in equine reproductive health. With further investigation, these discoveries could inform protocols to prevent reproductive failures perhaps linked to viral infections. As equine health professionals strive for improving mare reproductive success, understanding the biological significance of OaPVs in the vaginal virobiota may not just contribute to animal welfare but also agricultural productivity as horses play vital roles across many industries.
