World’s oldest cold virus that infected woman 250 years ago identified by scientists

While previously uncovered traces of ancient viruses dating back as far as 50,000 years have been found on human skeletons, those discoveries have largely involved DNA viruses.

RNA viruses, including the rhinoviruses responsible for the common cold, are far more elusive, inherently unstable genetic material which typically degrades within hours of death.

Human cells also generate RNA as part of the process of reading the genetic code and producing proteins, further complicating efforts to distinguish viral remnants from background material.

In recent years, researchers have gradually pushed back the boundaries of ancient RNA recovery. One team recently succeeded in extracting RNA from a woolly mammoth that died 40,000 years ago.

Yet such breakthroughs have typically depended on exceptionally well-preserved samples.

To overcome these challenges, scientists travelled to the Hunterian Anatomy Museum at the University of Glasgow, where lung tissue samples had been stored in alcohol.

The samples belonged to two individuals: a woman from London who died around the 1770s and another person, of unknown sex, who died in 1877. Both had documented evidence of severe respiratory disease.

Researchers were eventually able to reconstruct the complete RNA genome of a rhinovirus from the 18th-century woman.

Further analysis revealed she had also been infected with bacteria known to cause respiratory disease, including Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis.

The reconstructed viral genome was compared with a vast database maintained by the National Institutes of Health, containing millions of viral sequences from around the world.

It was found to belong to the human rhinovirus A group and represents an extinct lineage most closely related to the modern genotype known as A19.

“By comparing it to present-day viruses, we estimate that this historical virus and modern A19 last shared a common ancestor sometime in the 1600s,” said Dr Erin Barnett, of the Fred Hutchinson Cancer Centre.

Reflecting on the anonymous lives behind the samples, she added: “The stories of these two individuals are largely unknown, and we hope that this study serves to help recognise them.”

The team extracted both RNA and DNA from the preserved lung tissue. The RNA fragments recovered were, Dr Barnett said, “extremely fragmented”, with most pieces measuring just 20 to 30 nucleotides in length.

“To put that in perspective, RNA molecules in living cells are usually more than 1000 nucleotides long,” she said.

“So instead of working with long, intact strands, we were piecing together information from many tiny fragments.”

Nucleotides are the fundamental building blocks of nucleic acids that make up the ‘A’ in DNA and RNA, measuring just 0.34 nanometers in length - a fraction of one thousand-millionth of a metre.

Independent experts have hailed the findings as a breakthrough, according to the New Scientist. Love Dalén of Stockholm University described it as a landmark moment.

“It represents a really important discovery since it demonstrates the possibility of recovering RNA from wet collections that pre-date the use of formalin,” he said.

“This is the first phase in what will become an explosion in the study of RNA viruses.

“Many RNA viruses evolve fast, which means that studying them on timescales of several hundred years will yield highly important insights into virus evolution."

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