Investigadores de las universidades de Basilea y Z\u00farich han utilizado un esp\u00e9cimen hist\u00f3rico de la Colecci\u00f3n M\u00e9dica de la UZH para descifrar el genoma del virus responsable de la pandemia de gripe de 1918-1920 en Suiza. El material gen\u00e9tico del virus revela que ya hab\u00eda desarrollado adaptaciones clave en los humanos al inicio de lo que se convirti\u00f3 en la pandemia de gripe m\u00e1s mort\u00edfera de la historia. Se estima que se cobr\u00f3 entre 20 y 100 millones de vidas en todo el mundo.<\/p>\n
New viral epidemics pose a major challenge to public health and society. Understanding how viruses evolve and learning from past pandemics are crucial for developing targeted countermeasures. The so-called Spanish flu of 1918\u20131920 was one of the most devastating pandemics in history, claiming some 20 to 100 million lives worldwide. And yet, until now, little has been known about how that influenza virus mutated and adapted over the course of the pandemic.<\/p>\n<\/div>\n<\/div>\n<\/div>\n
More than 100-year-old flu virus sequenced<\/strong><\/p>\n An international research team led by Verena Sch\u00fcnemann, a paleogeneticist and professor of archaeological science at the University of Basel (formerly at the University of Zurich) has now reconstructed the first Swiss genome of the influenza virus responsible for the pandemic of 1918\u20131920. For their study, the researchers used a more than 100-year-old virus taken from a formalin-fixed wet specimen sample in the Medical Collection of the Institute of Evolutionary Medicine at UZH. The virus came from an 18-year-old patient from Zurich who had died during the first wave of the pandemic in Switzerland and underwent autopsy in July 1918.<\/p>\n<\/div>\n<\/div>\n<\/div>\n Three key adaptations in Swiss virus genome<\/strong><\/p>\n \u201cThis is the first time we\u2019ve had access to an influenza genome from the 1918\u20131920 pandemic in Switzerland. It opens up new insights into the dynamics of how the virus adapted in Europe at the start of the pandemic,\u201d says last author Verena Sch\u00fcnemann. By comparing the Swiss genome with the few influenza virus genomes previously published from Germany and North America, the researchers were able to show that the Swiss strain already carried three key adaptations to humans that would persist in the virus population until the end of the pandemic.<\/p>\n Two of these mutations made the virus more resistant to an antiviral component in the human immune system \u2013 an important barrier against the transmissions of avian-like flu viruses from animals to humans. The third mutation concerned a protein in the virus\u2019s membrane that improved its ability to bind to receptors in human cells, making the virus more resilient and more infectious.<\/p>\n<\/div>\n<\/div>\n<\/div>\n New genome-sequencing method<\/strong><\/p>\n Unlike adenoviruses, which cause common colds and are made up of stable DNA, influenza viruses carry their genetic information in the form of RNA, which degrades much faster. \u201cAncient RNA is only preserved over long periods under very specific conditions. That\u2019s why we developed a new method to improve our ability to recover ancient RNA fragments from such specimens,\u201d says Christian Urban, the study\u2019s first author from UZH. This new method can now be used to reconstruct further genomes of ancient RNA viruses and enables researchers to verify the authenticity of the recovered RNA fragments.<\/p>\n<\/div>\n<\/div>\n<\/div>\n Invaluable archives<\/strong><\/p>\n For their study, the researchers worked hand in hand with UZH\u2019s Medical Collection and the Berlin Museum of Medical History of the Charit\u00e9 University Hospital. \u201cMedical collections are an invaluable archive for reconstructing ancient RNA virus genomes. However, the potential of these specimens remains underused,\u201d says Frank R\u00fchli, co-author of the study and head of the Institute of Evolutionary Medicine at UZH.<\/p>\n The researchers believe the results of their study will prove particularly important when it comes to tackling future pandemics. \u201cA better understanding of the dynamics of how viruses adapt to humans during a pandemic over a long period of time enables us to develop models for future pandemics,\u201d Verena Sch\u00fcnemann says. \u201cThanks to our interdisciplinary approach that combines historico-epidemiological and genetic transmission patterns, we can establish an evidence-based foundation for calculations,\u201d adds Kaspar Staub, co-author from UZH. This will require further reconstructions of virus genomes as well as in-depth analyses that include longer intervals.<\/p>\n<\/div>\n<\/div>\n<\/div>\n