A remarkable discovery has identified a cold virus that infected a woman in London approximately 250 years ago, marking it as the oldest known human RNA virus.

Researchers, through advanced DNA sequencing techniques, have uncovered traces of various viruses in ancient human bones that date back as far as 50,000 years. However, many viruses, particularly rhinoviruses that are responsible for the common cold, contain RNA genomes, which are significantly more unstable than DNA and typically deteriorate within hours post-mortem.

RNA is also generated by our cells during the process of translating genetic code into proteins.

In recent years, scientists have successfully extended the recovery timelines for ancient RNA. Notably, a team managed to recover RNA from a woolly mammoth that lived 40,000 years ago.

“To date, much of the ancient RNA research has depended on well-preserved materials, such as permafrost samples or dried seeds, which restricts our understanding of historical human diseases,” remarks Erin Burnett of the Fred Hutchinson Cancer Center in Seattle, Washington.

Since the early 1900s, numerous tissues in pathology collections have been preserved using formalin, a method that fortifies RNA against rapid degradation. Barnett and her team sought to explore pathology collections across Europe for older human specimens that might contain preserved RNA.

Within the Hunterian Museum of Anatomy at the University of Glasgow, researchers discovered lung tissue samples from two individuals preserved in alcohol rather than formalin. One sample belonged to a woman who passed away around the 1770s, while the other was from an unidentified individual who died in 1877. Both exhibited documented cases of severe respiratory illness.

The researchers aimed to extract both RNA and DNA from the lung tissue of these individuals. Barnett described the RNA extracted from both samples as “extremely fragmented,” with the majority of fragments measuring just 20 to 30 nucleotides in length.

“For context, RNA molecules in living cells typically exceed 1000 nucleotides,” she explains. “Thus, instead of working with long, complete chains, we meticulously pieced together data from many smaller fragments.”

Gradually, the scientists succeeded in reconstructing the entire RNA genome of a rhinovirus extracted from the 18th-century woman. They also detected signs indicating she was infected with bacteria responsible for respiratory ailments, including Pneumococcus, Haemophilus influenzae, and Moraxella catarrhalis.

They compared the reconstructed ancient RNA viruses against a National Institutes of Health database featuring millions of viral genomes globally, including multiple rhinovirus strains.

This analysis revealed that the historic virus’s genome classified under the human rhinovirus A group, representing an extinct lineage most closely aligned with the modern genotype known as A19. “By comparing this with contemporary viruses, we deduce that the last time this historic virus and modern A19 shared a common ancestor was around the 1600s,” Barnett noted.

“The personal stories of these two individuals remain largely untold, and I hope this research brings them to recognition,” she expressed.

“This finding is significant as it demonstrates the potential to recover RNA from wet collections dated before the use of formalin,” said Love Darren at Stockholm University, Sweden.

“This marks the first step towards a surge of research into RNA viruses. Given that many RNA viruses evolve rapidly, studying them over centuries will yield vital insights into viral evolution,” he concluded.