Ancient Sheeppox Virus DNA Recovered from Medieval Manuscript Parchment

Sheeppox was largely eliminated from European livestock in the 20th century, but regional outbreaks still occur; last year, many flocks in Greece were hit. To reconstruct how the virus evolved over millennia, the research team turned to parchment, which is made from animal skins and can preserve ancient pathogen DNA.

Louis L'Hôte, a graduate student at University College Dublin and co-author of the study, said in a statement: “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.” He added that archives and libraries worldwide may hold genetic traces of past animal disease outbreaks. The recovered genomes, the authors write, help show how pathogens evolved and affected past societies.

The earliest known written evidence of sheeppox infection comes from first-century Roman accounts that described outbreaks of skin lesions called pustules in sheep. By the Middle Ages, agricultural and accounting documents in France, Spain, and England referred more frequently to deadly outbreaks of “pockes” or “variola” in flocks. The paper notes that outbreaks appeared to decline in 17th-century France but returned often with high death rates in the 18th and 19th centuries; Great Britain did not see a resurgence until 1847.