Hidden DNA in ancient gospel reveals 3,500-year history of deadly virus

Some of Europe’s most treasured historic manuscripts have turned out to be unlikely biological time capsules, preserving genetic traces of a devastating livestock disease that has plagued sheep for thousands of years.

An international team of researchers has reconstructed more than 3,500 years of the evolution of the sheeppox virus (SPPV) by extracting ancient DNA from animal skins used to make centuries-old parchment.

The findings, published in Science Advances, offer the first genetic evidence of how the highly contagious disease affected livestock long before the modern era.

Among the manuscripts analysed was the 1,000-year-old York Gospels, one of the finest surviving illuminated manuscripts from the early Anglo-Saxon period. Researchers also examined the Corpus Glossary of Corpus Christi College, Cambridge, one of the earliest English dictionaries, along with other medieval codices from Britain and continental Europe.

The results revealed traces of sheeppox virus DNA in several historic documents. In some cases, multiple pages from the same manuscript carried evidence of the virus, suggesting that animals infected with sheeppox may have been used to produce the parchment.

Parchment was traditionally made from the hides of livestock, including sheep, goats and cattle, effectively preserving a biological snapshot of an animal's health at the time of its death.

“Parchment can also preserve animal pathogen DNA,” said Louis L’Hte, a PhD candidate at University College Dublin and lead author of the study.

“It is possible that archives and libraries around the world also contain the genetic traces of disease outbreaks in animals in the past,” he said, adding that the findings show sheeppox had affected Eurasian sheep herds for at least three and a half millennia.

One of the study's more surprising discoveries was the detection of sheeppox virus DNA on parchment made from calfskin and goatskin. Researchers said this could point to rare cross-species infections or contamination during the parchment-making process.

The research also went beyond medieval manuscripts. By studying DNA preserved in Bronze Age sheep teeth recovered from ancient pastoralist settlements in the Eurasian steppe, scientists traced the disease even further back in time.

The findings suggest sheeppox has threatened livestock for more than 3,700 years, with the earliest known detections coming from ancient animal remains.

By comparing ancient and modern viral genomes, researchers estimated that the major lineages of capripoxviruses, including sheeppox, goatpox and lumpy skin disease, diverged between 11,500 and 3,700 years ago.

The timeline broadly coincides with the rise of animal domestication and the movement of sheep from the Eurasian steppe into Europe.

The virus remains a serious threat today, with outbreaks continuing to cause economic damage to livestock farmers.

Researchers said ancient genomes could offer crucial clues to understanding how pathogens evolved and may eventually help improve efforts to fight diseases that still threaten animal populations.