The world’s oldest cold virus found in the lungs of women from the 18th century

A cold virus that infected a woman in London about 250 years ago has been identified by genetic analysis, making it the oldest confirmed human RNA virus.

DNA sequencing has allowed scientists to find traces of some viruses in human skeletons as old as 50,000 years. But many viruses, including the rhinoviruses that cause the common cold, have genomes made of RNA, which is much less stable than DNA and usually degrades within hours of death.

Our cells also produce RNA as part of the process of reading the genetic code and translating it into proteins.

In recent years, scientists have pushed back the age at which they have been able to recover ancient RNA, with one team recently extracting RNA from a woolly mammoth that died 40,000 years ago.

“Until now, most ancient RNA studies have relied on exceptionally well-preserved materials such as permafrost samples or dried seeds, which greatly limits what we can learn about past human diseases,” he says. Erin Barnett at the Fred Hutchinson Cancer Center in Seattle, Washington.

Since the early 20th century, many tissues in pathology collections have been preserved in formalin, which protects RNA from complete and rapid degradation. Barnett and his colleagues set out to search pathology collections across Europe for human samples older than this one that might have been well enough preserved for the RNA to survive.

At the Hunterian Anatomy Museum at the University of Glasgow in the United Kingdom, the team found samples of lung tissue, preserved in alcohol rather than formalin, from two individuals—a woman from London who died around the 1770s, and a second person of unknown gender who died in 1877. Both had documented signs of severe respiratory disease.

The scientists then set about isolating both RNA and DNA from the lung tissue of both individuals. Barnett says the RNA obtained from both lungs was “extremely fragmented,” with most pieces averaging only 20 to 30 nucleotides.

“To put this into perspective, RNA molecules in living cells are typically more than 1,000 nucleotides long,” he says. “So instead of working with long, intact strands, we were piecing together information from many small fragments.”

Slowly, however, scientists managed to reconstruct the entire RNA genome of the rhinovirus from a woman from the 18th century. They also found evidence that she had been affected by bacteria that cause respiratory diseases such as Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis.

They then compared the old RNA virus they reconstructed with the US National Institutes of Health database, which contains records of millions of viral genomes, including many rhinoviruses collected from around the world.

This showed that the historical genome of the virus falls within the human rhinovirus A group and represents an extinct lineage that is most closely related to the modern genotype known as A19. “By comparison with contemporary viruses, we estimate that this historical virus and modern A19 last shared a common ancestor sometime in the 1600s,” says Barnett.

“The stories of these two individuals are largely unknown, and we hope that this study will serve to bring them to light,” he says.

“This is a really important discovery because it shows the possibility of getting RNA from wet collections that predated the use of formalin,” he says I love Dalén at Stockholm University in Sweden.

“This is the first phase of what will become an explosion in the study of RNA viruses. Many RNA viruses evolve rapidly, which means that studying them over a time horizon of several hundred years will yield very important insights into the evolution of viruses,” he says.

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