The seasonal influenza virus H1N1 could be a direct descendant of the virus responsible for the Spagnola pandemic, which between 1918 and 1919 killed between 50 and 100 million people worldwide: the clues come from the analysis of 13 genetic samples collected in Europe between 1901 and 1931, six of them in the two years of the pandemic.
This is indicated by the study published in the journal Nature Communications and led by the Robert Koch Institute in Berlin and the Rega Institute in Leuven, Belgium.
Genetic analysis of the 1918 Spanish Flu virus is very difficult due to the rarity of samples dating back to that period.
Only in the 1930s, in fact, it was possible to confirm that the pandemic had a viral origin, while the hypothesis that the virus responsible was of the H1N1 subtype is even more recent.
The researchers were able to access 13 lung tissue samples preserved in the historical archives of museums in Germany and Austria and, by analyzing them from the genetic point of view, they obtained two partial and one complete genomes in samples taken in 1918 in Berlin and Munich. .
The samples were then compared with others, which dated back to different periods, before and after the peak of the Spanish.
An important mutation was thus identified in a gene associated with resistance to the immune response, which could also be responsible for the adaptation of the virus to humans.
The genetic material also made it possible to estimate the evolution over time of the current H1N1 virus: it emerged that all its genomic segments could descend directly from the 1918 pandemic strain. A result that contradicts alternative hypotheses, according to which the virus influenza allegedly originated from an exchange and reassortment of genetic material between different viruses.