Ancient viral DNA discovered in medieval parchment reveals that sheeppox virus was spreading through European sheep flocks for at least 3,500 years.
Researchers at University College Dublin led an international study examining animal skins used to produce historical texts like the 1,000-year-old York Gospels and the Corpus Glossary at Corpus Christi College Cambridge. The team found that parchment preserves biological history alongside cultural heritage. Sheeppox remains a highly contagious disease affecting livestock today.
“The recording of ancient DNA of pathogens has completely changed our understanding of infectious disease in the past, and here we show that parchment can also preserve animal pathogen DNA,” said Louis L’Hôte, PhD candidate at University College Dublin and lead author of the study.
Scientists also recovered DNA from sheep teeth dating back to the Bronze Age to trace the disease further into the past. These teeth samples came from ancient pastoralist settlements located in the Eurasian steppe.
Comparing ancient viral sequences with modern genomes showed that the capripoxvirus family split between 11,500 and 3,700 years ago.
This timeline lines up with early livestock domestication and the large-scale movement of sheep into Europe. The genome of the sheeppox virus stayed remarkably stable over millennia.
“People around the world are still fighting against this pathogen — there is currently an outbreak of sheeppox in Greece, causing much economic damage,” L’Hôte said.
The project combined researchers across genetics, history, virology, protein chemistry, and conservation. More than 30 institutions across Ireland and internationally contributed to the findings published in Science Advances.
“This kind of exciting, surprising discovery is only possible when researchers from a range of disciplines come together to share their expertise and data — a generosity and trust that collaborative science depends on,” said Dr. Kevin G. Daly, Associate Professor at University College Dublin School of Agriculture and Food Science and the supervising author of the study.
Taighde Éireann-Research Ireland and the European Research Council funded the research. Participating institutions include Trinity College Dublin, the Helmholtz Institute for One Health, Université Paris 1 Panthéon-Sorbonne, the University of Leicester, Cambridge University, and the University of Copenhagen.