Scientists extract sheeppox virus DNA from medieval manuscripts to trace 3,500 years of viral evolution
Researchers sequenced pathogen DNA preserved in animal-skin parchment to reconstruct the genetic history of a livestock disease that devastated European sheep herds across centuries.
What happened
Scientists extracted and sequenced sheeppox DNA from medieval manuscripts made of sheep parchment to reconstruct the virus's evolution over at least 3,500 years, according to a study published in Science Advances. The earliest written evidence of sheeppox infection dates to the first century CE in Roman accounts describing skin lesions in animals, with more frequent documented outbreaks recorded in medieval agricultural texts and accounting documents from France, Spain, and England. The research team analyzed DNA from these historical sources because traditional genetic history of the sheeppox virus was largely unknown, and recent analytical techniques have made it possible to extract pathogen DNA from ancient parchment.
Context
Sheeppox is a highly contagious viral disease that was largely eradicated from European livestock in the 20th century but continues to cause occasional regional outbreaks, such as one in Greece in the recent past. The historical record shows outbreaks declined in 17th-century France but resurged frequently in the 18th and 19th centuries with high mortality rates, and did not spread to Great Britain until 1847. This work demonstrates that archived parchment and manuscripts globally may contain genetic traces of past animal disease outbreaks, offering a novel way to understand how pathogens evolved and their impact on historical societies.