Using preserved tissue from an 18-year-old who died during the first wave of the 1918 flu pandemic, scientists in Switzerland have reconstructed the genome of the virus strain circulating in Zurich at the time. The research, led by Verena Schünemann of the University of Basel, adds to the limited genomic data available from the 1918–1920 pandemic and offers a clearer picture of how the virus had already adapted to humans in Europe early on.
The sample came from a formalin-fixed wet specimen held in the Medical Collection at the University of Zurich. Although over a century old, the tissue still contained fragments of viral RNA. Influenza viruses carry RNA rather than DNA, which degrades more rapidly, making historical reconstructions particularly difficult. To address this, the team developed a new sequencing method optimized for recovering ancient RNA.
“This is the first time we’ve had access to an influenza genome from the 1918–1920 pandemic in Switzerland,” Schünemann said. “It opens up new insights into the dynamics of how the virus adapted in Europe at the start of the pandemic.”
Comparative analysis with other sequences from Germany and North America showed the Swiss virus had already acquired three key mutations. Two conferred resistance to antiviral factors in the human immune system, and a third enhanced the virus’s ability to bind to human cell receptors.
The study also highlights the overlooked value of medical collections. “Medical collections are an invaluable archive for reconstructing ancient RNA virus genomes. However, the potential of these specimens remains underused,” said Frank Rühli of the University of Zurich.
Publication Details
Urban, C., Vrancken, B., Patrono, L.V. et al. An ancient influenza genome from Switzerland allows deeper insights into host adaptation during the 1918 flu pandemic in Europe. BMC Biol 23, 179 (2025). https://doi.org/10.1186/s12915-025-02282-z
The sample came from a formalin-fixed wet specimen held in the Medical Collection at the University of Zurich. Although over a century old, the tissue still contained fragments of viral RNA. Influenza viruses carry RNA rather than DNA, which degrades more rapidly, making historical reconstructions particularly difficult. To address this, the team developed a new sequencing method optimized for recovering ancient RNA.
“This is the first time we’ve had access to an influenza genome from the 1918–1920 pandemic in Switzerland,” Schünemann said. “It opens up new insights into the dynamics of how the virus adapted in Europe at the start of the pandemic.”
Comparative analysis with other sequences from Germany and North America showed the Swiss virus had already acquired three key mutations. Two conferred resistance to antiviral factors in the human immune system, and a third enhanced the virus’s ability to bind to human cell receptors.
The study also highlights the overlooked value of medical collections. “Medical collections are an invaluable archive for reconstructing ancient RNA virus genomes. However, the potential of these specimens remains underused,” said Frank Rühli of the University of Zurich.
Publication Details
Urban, C., Vrancken, B., Patrono, L.V. et al. An ancient influenza genome from Switzerland allows deeper insights into host adaptation during the 1918 flu pandemic in Europe. BMC Biol 23, 179 (2025). https://doi.org/10.1186/s12915-025-02282-z