Medieval manuscripts and ancient animal remains have yielded genetic traces of the sheeppox virus, offering new insight into a disease that has threatened livestock for thousands of years. According to a study published in Science Advances, researchers recovered ancient DNA of the sheeppox virus, or SPPV, from animal skins utilized in historical parchment production.
Medieval Manuscripts Reveal Ancient Sheeppox Viral DNA
The collaborative research team gathered samples from medieval manuscripts housed in collections at institutions including Yale University, Cambridge University, Corpus Christi College, University College Dublin, the Lambeth Palace Library, and Trinity College. Among the analyzed artifacts were pages from a 15th-century Speculum Historiale, 15th-century Clairvaux manuscripts, several 9th-century gospel text fragments, the 9th-century Achadeus Psalter, the early 11th-century Trinity Gospels, the Lambeth Bible, and the 1,000-year-old York Gospels.
Infected Flocks and Surprising Animal Hosts
Sheeppox is a highly contagious disease that spreads quickly through flocks, frequently killing young animals while diminishing wool, meat, and milk yields. Historically, these agricultural losses posed direct threats to food supplies and farming communities across Eurasia.
Researchers detected viral DNA across multiple pages within several manuscripts originating from Britain and mainland Europe. This distribution pattern indicates that craftspeople utilized hides from infected livestock when preparing writing surfaces. The collection also included viral DNA discovered within parchment linked to the Corpus Glossary at Corpus Christi College, Cambridge, which stands as one of the earliest English dictionaries.
In addition to sheep-derived material, investigators found sheeppox virus evidence on parchment manufactured from calfskin and goatskin. These unexpected detections point toward rare cross-species infections or potential contamination events occurring during the skin-processing phase.
Tracing Virus Evolution and Stability
To establish a broader evolutionary timeline, the team extracted ancient DNA from Bronze Age sheep teeth collected at pastoral settlement sites located on the Eurasian steppe in Russia and Central Kazakhstan. Combining these dental samples with medieval genomes provided a comprehensive record spanning from approximately 1700 BCE to the Early Modern period.
Genetic comparisons positioned SPPV within the wider capripoxvirus group. The study estimates that the main lineages leading to sheeppox virus, goatpox virus, and lumpy skin disease virus diverged between approximately 11,500 and 3,700 years ago. This timeframe correlates with the expansion of animal domestication and the movement of sheep into new territories, including Europe.
Unlike the smallpox virus, the sheeppox virus demonstrated notable genetic stability over the millennia examined by the team. We find that unlike the smallpox virus, the sheeppox virus genome was very stable over the last few millennia,
noted L’Hôte, adding that earlier genetic alterations likely shaped how the pathogen adapted to infect its hosts.
Modern Relevance and Implications
The findings emphasize that historical book bindings and writing supports function as biological archives rather than mere repositories of text. Parchment making has been considered a vanishing craft, but we are beginning to understand just how much of the past it has retained,
stated co-author Kevin G. Daly of University College Dublin. He noted that such discoveries rely on interdisciplinary collaboration across scientific and historical fields.
The disease remains a contemporary agricultural concern. Recent outbreaks, such as an epidemic affecting sheep and goats in Greece, continue to cause economic damage and disrupt food production. By comparing ancient viral genomes with modern strains, researchers hope to better understand pathogen evolution and support future efforts to combat livestock diseases.