Archaeologists say they have found evidence for the oldest ever recorded Hepatitis B virus (HBV) in human history, as part of a broader project looking at human migration.
In papers published in both Nature and Science, teams sequenced the genomes of skeletons from humans stretching over a huge area, from Hungary to northeastern China, spanning about 8,000 kilometers (5,000 miles).
The large project was intended to produce a new genetic map of human migration across Eurasia. But in one of the papers, a team led by Professor Eske Willerslev from the University of Copenhagen in Denmark made an additional discovery that could reveal the origins of HBV.
They sequenced the DNA of more than 300 humans, stretching in time from 1,500 to 4,500 years ago, and found that 25 of these individuals had evidence for HBV infections, including strains that are now extinct, suggesting the virus was widespread across Eurasia and has evolved over time.
“This would be the oldest virus recorded,” Willerslev said in a press conference. “It’s very interesting because it allows you to address very fundamental questions about the evolution and development of this disease.”
Today, about 257 million people in the world are chronically infected with HBV. In 2015, around 887,000 people died from complications caused by the disease. How the virus began and evolved over time has been unclear, however.
Some think HBV co-evolved with humans as they left Africa 60,000 to 100,000 years ago, but the researchers noted in their paper that such an idea “has been contested”. While not seeking to solve that problem, this research does get us closer to an answer.
The remains in this research were found all over the steppes of Eurasia. Not all were excavated as part of this research, with some having been dug up 60 years ago. But there were some interesting findings, including little genetic mixing between certain groups.
The discovery of HBV in the genomes was a “bonus,” study co-author Peter der Barros Damgaard, from the Natural History Museum of Denmark, told IFLScience. “We were looking for all pathogens in the data, and found HBV was actually widespread,” he said.
Prior to this discovery, the oldest evidence of a virus we had was also HBV, stretching back just 400 years. We’ve also seen the variola virus dating back 350 years, and influenza dating back about 100 years.
The spread of HBV among humans in Eurasia, which appears to have occurred over thousands of years, could tell us more about how humans spread over time. The modern spread of HBV, for example, does not match the distribution associated with this research. It could also help us combat various forms of HBV today.
“It provides us with a possibility of testing their impact and if needed make vaccines against them,” Willerslev told IFLScience. “When they have been there in the past, they may come again.”
