What's Happening?
A research team, primarily from University College Dublin, has successfully recovered 21 new genomes of the sheeppox virus, with the oldest dating back to between 1875 and 1645 BC. These ancient genomes were extracted from sheep molars found at Late Bronze
Age settlements in central Kazakhstan and Russia, as well as from the parchment pages of medieval books, including the York Gospels, a Latin glossary from around 800 AD, and a copy of the Epistles of St Paul. The study, published in Science Advances, marks the recovery of the oldest known poxvirus genomes. Sheeppox is a highly contagious and often fatal disease for sheep, with morbidity rates reaching 75-90% and mortality around 50% in immunologically naive flocks. The virus significantly impacts milk, wool, and meat production and leaves scars on animal hides. The discovery highlights the potential of historical artifacts, such as medieval manuscripts made from animal skins, as unexpected archives for ancient pathogen DNA.
Why It's Important?
The recovery of these ancient sheeppox virus genomes offers unprecedented insights into the evolutionary history and stability of poxviruses over millennia. Unlike smallpox, which showed progressive gene inactivation over time, the sheeppox virus genome has remained remarkably stable since the Bronze Age, with key gene inactivations already present in the oldest samples. This stability suggests that the virus adapted to its sheep host much earlier than previously understood. Understanding the long-term genetic stability of sheeppox can inform current and future strategies for combating the disease, which remains a notifiable illness under the World Organisation for Animal Health and continues to cause outbreaks, such as a recent one in Greece. Furthermore, the methodology of extracting viral DNA from parchment opens new avenues for paleovirology, demonstrating that libraries and archives worldwide may contain genetic traces of past animal disease outbreaks, providing a unique 'tissue bank' for historical epidemiological research.
What's Next?
The research team plans to seek ancient genomes for related viruses, such as goatpox and lumpy skin disease, potentially using similar methods of extracting DNA from animal skin documents. This could further clarify the evolutionary relationships and divergence times among capripoxviruses. The findings also encourage a broader re-evaluation of historical artifacts as sources of biological data, suggesting that more extensive screening of parchment collections could reveal a wealth of information about past animal health and disease patterns. Future studies might focus on refining DNA extraction techniques from delicate materials and developing more robust phylogenetic analyses to resolve uncertainties in viral family trees. The insights gained could contribute to a better understanding of disease emergence, transmission, and long-term ecological impacts, potentially aiding in the development of more effective disease control and prevention measures in livestock.
Beyond the Headlines
This discovery transcends traditional historical and biological research by bridging the gap between ancient texts and modern genomics. It underscores the unexpected utility of cultural heritage materials, like medieval manuscripts, not just for their artistic or literary value, but as scientific repositories. The ability to extract and sequence ancient viral DNA from such sources challenges conventional notions of where biological data can be found and preserved. This interdisciplinary approach highlights the interconnectedness of history, archaeology, and molecular biology, offering a unique perspective on the co-evolution of pathogens and their hosts. It also raises ethical considerations regarding the handling and analysis of historical artifacts for scientific purposes, balancing preservation with the pursuit of new knowledge. The stability of the sheeppox genome over thousands of years provides a compelling case study for understanding viral evolution and could have implications for predicting the long-term behavior of other animal and human pathogens.
