UCD team recovers 21 ancient sheeppox virus genomes from Bronze Age teeth and medieval parchment
The genomes span about 1700 BCE to the Early Modern period. The data show that sheeppox has threatened Eurasian livestock for more than 3,700 years.
Researchers led by University College Dublin (UCD) have reconstructed 21 new ancient genomes of sheeppox virus (SPPV), the cause of a disease that reduces production and kills vulnerable sheep, according to a study in Science Advances. doi.org
Science Advancesdoi.orgOpen source ↗ The genomes span the Bronze Age of the Eurasian steppe (about 1700 BCE) to the Early Modern period in Western Europe, and several come from medieval parchment. The project involved more than 30 institutions, including Trinity College Dublin, the University of Leicester, Cambridge University and the University of Copenhagen.
Viral DNA in parchment and sheep teeth
Parchment was made from carefully prepared hides of sheep, goats and cattle, and can retain traces of infections present when the animal died. The manuscripts examined included the York Gospels, about 1,000 years old, the Corpus Glossary at Corpus Christi College Cambridge, and other medieval manuscripts from Britain and continental Europe. In several of them, SPPV DNA was detected on multiple pages.
Viral DNA was also found on parchment made from calfskin and goatskin. Because sheeppox mainly infects sheep, the researchers name two possibilities: occasional infection of other livestock species, or contamination of the skins during parchment production.
The oldest genetic traces of the virus came from sheep teeth recovered from pastoralist settlements on the Eurasian steppe. Together with the manuscript data, they show that sheeppox has affected livestock for more than 3,700 years. doi.org
Science Advancesdoi.orgOpen source ↗
Divergence timeline and a stable genome
By comparing ancient and modern sequences, the team estimated that the major capripoxvirus lineages diverged about 11,500 to 3,700 years ago. This interval overlaps known translocations and bio-cultural developments in sheep, including domestication and the movement of sheep from the steppe into Europe. The dataset supports SPPV diverging first within the lineage leading to goatpox virus and lumpy skin disease virus. Known gene inactivation events in SPPV and goatpox virus are already present in the earliest SPPV genomes.
Lead author Louis L'Hôte said that, unlike smallpox virus, the SPPV genome was very stable over the last few millennia. He suggested that genetic changes before that period may have been important for the virus's adaptation to its host. Sheeppox remains a practical problem: L'Hôte noted a current outbreak in Greece that is causing economic damage.
