Researchers decode Swiss Spanish flu virus genome

(CONNECT) An international team of researchers led by the Universities of Basel and Zurich(UZH) have succeeded for the first time in reconstructing the Swiss viral genome of the Spanish flu, which raged worldwide from 1918 to 1920. According to a statement, this virus already contained three key adaptations to the human host at the beginning of the deadliest influenza pandemic. So far, little is known about how the influenza virus at the time has changed due to mutations during the course of the pandemic, according to the press release. The specimen examined, which is over 100 years old, comes from an 18-year-old patient from Zurich who died during the pandemic. It was in the medical collection of the Institute of Evolutionary Medicine at UZH as a formalin-fixed wet specimen.

"For the first time, we have an influenza genome from the 1918-1920 pandemic from Switzerland," said research leader and palaeogeneticist Verena Schünemann in the press release. "This gives us new insights into the dynamics of how the virus adapted in Europe at the beginning of the pandemic." The researchers have also developed and applied a new method to improve the extraction of these old RNA fragments.

By comparing this sample with previously studied influenza virus genomes from Germany and North America, the team recognized that the Swiss virus genome already had three key adaptations to humans. According to the announcement, this key adaptation remained in the virus populations until the end of the pandemic. Two mutations made the virus more resistant. In the third adaptation, a protein in the virus membrane was modified so that it could bind more easily to receptors in human cells. This made the virus more infectious.

The researchers see their findings as an important contribution to combating future pandemics. "If we can better understand the dynamics of how viruses adapt to humans over a long period of time during a pandemic, we can develop models for future pandemics," says Verena Schünemann. The reconstruction of further virus genomes is planned for this purpose. The results have now been published in the journal "BMC Biology". ce/eb