The virus of seasonal flu it could be a vestige of the pathogen that in 1918 triggered the great global pandemic of the 20th century. Or put another way. The microorganism that caused the (misnamed) Spanish flu could have become, over time, the virus that year after year causes a seasonal flu epidemic. At least this is the hypothesis defended by an international team of researchers after rescuing a handful of samples from patients who became ill a century agodecipher the genome of the virus that became entrenched in their lungs and trace the possible evolution of this pathogen to the present day.
This exercise ofviral archeology“, published this Tuesday in the scientific journal ‘Nature Communications’has allowed to travel back in time to explore with genetic tools a time that until now had only been studied through historical records. To find out what the virus that caused the Spanish flu was like, and what the effects of its infection were, the scientific team led by Sébastien Calvignac-Spencer investigated the Historical records from various museums in Germany and Austria, located a dozen lung samples collected between 1901 and 1931 (of which at least six coincide with the critical years of the pandemic in the last century) and reconstructed the genome of the enigmatic virus that just a century ago infected the world.
The analysis of these samplesuntil now stored on the shelves of a museum, has not only allowed us to delve into the microorganism genome that a hundred years ago it caused between 50 and 100 million deaths around the globe; It has also helped map out the possible evolution of this virus through the decades. Thanks to a technique known as molecular clock, which allows us to deduce the genetic divergences of a species in time, the scientists responsible for this analysis have concluded that “all the genomic segments of the seasonal H1N1 flu could be directly descended from the initial pandemic strain of 1918“In other words, everything points to the fact that the current seasonal flu is the daughter, or rather great-granddaughter, of a pandemic virus from the last century.
According to the epidemiologist Xavier of the Eaglethe evolution of viruses (like any other living being) is something natural. It is only necessary to remember how the coronavirus responsible for the covid-19 pandemic has mutated and generated a battery of variants in just two years. In this sense, then, it would not be unreasonable to think that a virus as deadly as the Spanish flu would transform over the years into something much lighter, as in the pathogen that causes cases of seasonal flu. Of course, if we are to draw parallels with the covid-19 health crisisand the future of this coronavirus, del Águila recalls that not all viruses evolve into milder formsyes Only time, evolution and chance will tell where the pathogen that is leading the current pandemic is going.
viral discussion
This conclusion, far from being presented as an end point in this viral debate, moves in the field of hypotheses. In the discussion forum where the scientific community assembles and disassembles theories based on how scientific evidence advances. “This studio opens the possibility that the current seasonal flu comes from the 1918 pandemic virus. And this, in turn, contradicts the most accepted hypothesis Until now, it was suggested that seasonal flu came from a rearrangement of different human viruses”, illustrates the virologist Jose Ignacio Nunezresearcher at the Animal Health Research Center (IRTA-CReSA) and independent expert questioned by this newspaper.
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Beyond the conflict between viral hypotheses, Núñez argues that the most interesting aspect of the recently published research is “the possibility that it raises re-study the past with new technological tools“. When the first cases of Spanish flu broke out, in 1918, the doctors of the time did not even know what triggered the disease. It was not until the 1930s that it was confirmed that this strange disease that affected tens of thousands of soldiers it was caused by a virus. Now, a century later, “thanks to genetic sequencing tools we can investigate the origin and evolution of a virus that caused a pandemic,” says Núñez.
The study of these samples viral infections has also made it possible to extend the history of the Spanish flu. As explained by the scientific team responsible for this study, in fact, just as has happened now with the covid-19 pandemic, the pandemic virus of the last century was also mutating from local broadcast events and in long distance scattering moments. The analysis also reveals that after the peak of the pandemic, a series of mutations related to antiviral responses were detected that could have allowed the adaptation of the virus to humans.