Sometime between 600 and 450 B.C.E., a high-status individual in what is today Germany developed some disturbing symptoms: large bruises, bleeding from the nose and gums, and bloody diarrhea and urine. His fellow villagers, shocked—or perhaps intrigued—by his condition, stored his blood and organs in pottery vessels after he died, and interred them in a burial mound. Now, using a novel technique based on analyzing ancient proteins, archaeologists have reconstructed the contents of these vessels to conclude that the individual likely died from Crimean-Congo hemorrhagic fever virus (CCHFV), a severe tick-borne disease that still kills people across the world today.
"This is the first identification of CCHFV or any hemorrhagic fever virus in the archaeological record," says Conner Wiktorowicz, the study's lead researcher and a Ph.D. candidate in archaeology at Purdue University in West Lafayette, Indiana. It’s also the only known example of human blood and organs being buried in pottery vessels during this time in this region, raising the question of whether this was a more widespread practice, previously unknown to archaeologists.
The contents of ceramic vessels decay over time, leaving a film of residue containing proteins from any organic matter stored within. Archaeologists are exploring new ways to recover and analyze these proteins. In the new study, a team led by Wiktorowicz ground up a small portion of each of the pottery fragments (or sherds), used detergent and other chemicals to dislodge any proteins stuck to them, and isolated and analyzed the protein fragments using various techniques. The team then fed this information into a national protein database.
The researchers identified proteins specific to human blood and organs, which was a surprise, and showed that the vessels once held organ remains. Just as shocking was the presence of two unique protein fragments, known as peptides, that help CCHFV bind to a host cell just prior to infection, the team will report in the February 2017 issue of The Journal of Archaeological Science.
The find highlights how ancient viruses can more easily be identified by their proteins than their more commonly studied nucleic acids, such as DNA or RNA. Although researchers have used DNA to trace the prehistory of pathogens such as smallpox, proteins are more stable than nucleic acids and potentially could be preserved for millions of years.
"Recovering nucleic acids from ancient viruses is extremely difficult and plagued by contamination,” notes Angelique Corthals, a forensic anthropologist at the City University of New York in New York City, who was not involved in the study. "Virus proteins are more readily accessible and less prone to degradation."
"The discovery of proteins for CCHFV in the pottery sherds is very exciting,” Corthals says. "It would be nice to see confirmation by another independent laboratory. But as it is, the results seem pretty convincing."
The question remains as to whether the presence of CCHFV in Iron Age Germany represents evidence of an ancient epidemic, shows that the pathogen was endemic to the region, or traces the path of an individual who traveled from an infected area, Corthals says.
The findings could make archaeologists pay more attention to featureless pottery sherds, or those found moved from where they had been placed or discarded in antiquity, Wiktorowicz says. "What have archaeologists been missing regarding social practices and the use of pottery vessels in the past?" he says. “I can’t imagine all of the exciting new findings other researchers will make."