Variants of the virus that cause pandemic flu are increasingly dangerous

When studying virus samples of the last century, German scientists determined that the Influenza virus that caused the 1918 flu pandemic had mutated into new strains, like the corona virus in the Covid-19 pandemic. The discovery by scientists at the Robert Koch Institute in Berlin could explain why later outbreaks of the 1918 flu were worse than the first.

"The research results, although not directly applicable to the Covid-19 pandemic, show that humans can eventually overcome their variants. This is being expected by the world in the context of the corona virus outbreak. evolved with many dangerous mutations today," evolutionary biologist Sébastien Calvignac-Spencer, lead author of the study, told Live Science.

The warehouse was converted into an isolation area for infected people during the 1918 flu pandemic. (Photo: According to Live Science).

According to Spencer, as now, when focusing on studying the virus that caused the 1918 flu pandemic , the research team questioned whether its new variants would behave differently from the original? Since then, the team has studied six human lungs dating from the pandemic years of 1918, which are preserved in formalin at pathological archives in Germany and Austria. The researchers determined that three of the six sample lungs - two from young soldiers who died in Berlin, the other from a young woman who died in Munich - contained the 1918 flu virus.

"The virus that caused the 1918 flu pandemic is still around today. But it's more attenuated, mainly because we are descendants of people who survived the outbreak 103 years ago. Because So we've inherited some form of genetic immunity , " explains Calvignac-Spencer.

Estimates suggest that the 1918 strain of influenza infected about 1 billion people, while the global population was only 2 billion. About 50-100 million people may have died in three consecutive outbreaks then. The first wave of the pandemic occurred in early 1918, it was less deadly than later waves: "The preserved lungs of 2 German soldiers were determined to be dead at this time", the research team at the Institute of Robert Koch confirmed.

The researchers extracted viral RNA from those lung samples. Both German soldiers died on the same day and when decoding the genome of the virus that killed them there was almost no difference. Spencer added: "But the form of the flu virus found in the soldiers' lungs, is somewhat genetically different from the form of the virus that infected the young woman who died in Munich. Presumably, the woman. was not able to survive in a later outbreak". 

The scientists also compared the genomes of viruses from the US and Germany, and conducted laboratory studies with synthetic copies of virus samples. They wanted to learn to assess the infectivity and replication ability of different strains inside cells.

The findings of German scientists also show that the influenza virus of 1918 mutated to make the next outbreak stronger and more dangerous than the previous one, by evolving to overcome the ability of humans to "self-defence" . The genetic mutations that emerged between the first and second waves may have made the virus better adapted for human-to-human transmission, rather than between birds, its natural host.

The other mutation may have changed the way the virus interacts with a human protein called MxA , which helps regulate the body's immune response to new pathogens.

Although the scientists are not sure how the variants changed the "strength" of the virus, "it can be predicted that these changes helped the virus avoid one of the mechanisms by which cells respond." to kill the flu virus," Calvignac-Spencer said.

The evolution of the virus that caused the 1918 flu pandemic has similarities with the current Covid-19 pandemic, such as consecutive outbreaks with many different strains, and the following outbreaks are more dangerous than the previous one. .

Thanks to the advancement of science, today when understanding the Covid-19 pandemic, researchers can better understand the influenza pandemic of 1918: "The more we understand about the current pandemic, that The more we can understand the pandemic in the past, rather than vice versa," emphasized Calvignac-Spencer.

One significant advance is that researchers have been able to accurately sequence the viral genome in human tissue preserved in formalin for more than 100 years - something that has hitherto been thought to be very difficult.

"Thanks to new techniques, final research much easier than we expected", experts calvignac-Spencer added: "Now we can decode the genome of viruses from the infected individual buried in permafrost for up to 1,000 years, because the cold can help preserve DNA even longer."

The team of German scientists also want to sequence viral genomes that could be stored in the bodies of ancient Egyptian mummies - the earliest mummies are about 5,000 years old. "The mummies have been prepared to block biological processes, and that's exactly what we want. So we'll also embark on research to better understand other diseases in the future. the past" , the German scientist said about the group's plans in the future.