Modern influenza is a direct descendant of the virus that caused the 1918 pandemic.

Seasonal flu According to new research, it is a direct descendant of the 1918 pandemic and may not be the result of a combination of multiple viruses.

Just as the thousands of years of the human genome provide important information about where, when, and how our species evolved, viral genomic changes tell us about the progression of disease outbreaks. increase. Pandemic..

The 1918 pandemic It is estimated that 50 to 100 million people have died worldwide. Unlike today’s pandemics, many of the 1918 pandemic questions remained a mystery due to technical limitations.In particular, virologists are wondering if the seasonal H1N1 flu is a direct descendant of the 1918 pandemic. Reassortment within subtypes.. In other words, one of the biggest questions medical historians have about the 1918 pandemic is whether modern seasonal influenza is the great-grandchild or distant relative of the influenza virus that caused the 1918 pandemic.

New research published today Nature CommunicationsSuggests that seasonal flu is a direct descendant of the 1918 flu. This was a mystery, as scientists hadn’t done so yet at the time. Influenza virus discovered, Has little ability to sequence the viral genome. It wasn’t until the late 1990s that researchers could use the bodies preserved in permafrost to determine that the 1918 pandemic was actually the H1N1 subtype influenza A virus. ..

background- Researchers using new techniques Sebastien Calvignac-Spencer His colleagues at the Robert Koch Institute in Berlin, Germany, found out how closely modern seasonal influenza is associated with the 1918 virus and how the virus mutated throughout the 1918 pandemic. I was able to judge.

Calvinac-Spencer says reverse The value of using new technologies to understand the evolution of past pandemic viruses.

“With these types of tools, we can reconstruct how the virus emerged, spread, and adapted during a pandemic. Identifying different or similar ones between pandemics is the next catastrophe. It helps to better prepare for a pandemic, “he says.

What they did — Researchers have sequenced the virus from 13 lung samples of people who died of the flu between 1901 and 1931. The lungs were stored in museums in Berlin and Vienna, Austria. Three of the samples were taken from people who died in 1918.

Calvignac-Spencer states: [of] It sequences all RNA molecules in a particular sample, “he explains. “Because pathological specimens are usually formalin-fixed. [a water based-solution of formaldehyde gas], This blocks some of the RNA molecules by binding them to other macromolecules.Fine-tuned [this] By literally adding a step to boil the sample, this step releases some of the blocked RNA. “

Ultimately, researchers were able to sequence one complete genome and two partial genomes. Of particular interest to Calvignac-Spencer is the evolution of the virus to evade the defense of the immune system. In other words, the virus may have evolved to circumvent human immune defenses. Specifically, the immune system attacks the exposed virus by sending interferon and recognizing the virus’s nucleoprotein. Calvignac-Spencer and his colleagues discovered two sites of nucleoprotein that changed between the first and second waves of the pandemic. Modifying that nucleoprotein disrupts the system, allows reinfection and contributes to the second wave.

“Of course, the genome is still very small, but it’s an interesting tool for further investigation,” he says.

Finally, the researchers said,Molecular clock Model — to assess changes in the viral genome over time.according to Pennsylvania State University“Evolutionary biologists can use this information to infer how a species evolves and correct the date when the two species diverged in the evolutionary timeline.”

In this way, researchers found that early strains of influenza naturally in humans, birds, and other mammals, rather than becoming a recombinant virus that combines parts of the genome of different viruses into a unique virus. I was able to confirm that it has evolved. Some claimed that the flu had occurred.

Instead, researchers have determined that what we experience as seasonal influenza is actually a direct descendant of the 1918 influenza virus. Fortunately for us, it’s a much weaker version and one of our immune systems has combat experience.

What does this tell us about our current Covid-19 pandemic? — “By studying past pandemics, we can identify similarities and differences that tell us what a pandemic looks like. Similarities between the 1918 flu and the current pandemic. There is a difference, “says Calvignac-Spencer. “For example, both are occurring like waves. Still, the various waves of Covid’s pandemic are often caused by the epidemic of new variants, but in 1918 the replacement of such strains I can’t see it. “

The long-term goal is to build a stronger understanding of the pandemic, he says. Instead of using this 1918 pandemic to understand the current pandemic, he is interested in using the current pandemic to better understand the 1918 pandemic and the general pandemic.

What’s next– Calvignac-Spencer states: “The main limitation of our research and this kind of research is that the number of specimens / genomes we can actually play with is limited. Over 10 million we have collectively generated. Imagine trying to reconstruct a COVID pandemic with 20 genomes instead. “

If the current pandemic data is as low as it was in the 1918 pandemic, you will miss all variants and phases of the pandemic. Therefore, Calvignac-Spencer is interested in expanding the genomic data of the 1918 pandemic as much as possible.

“We are working hard to find new specimens in preparation for the 1918 pandemic. This area is very supportive (many laboratories are working together) and the museum is I am very happy to support this study, but it is very difficult, “he says. “We have already begun to extend the flu epidemic in 1957-58 and 1968-69. If you’re lucky, early, like the now-famous Russian cold of 1889/90. Specimens from a pandemic may also be found. The causative agent may have been influenza or one of the currently prevalent human coronaviruses (OC43). “

Ultimately, building a genomic history of past pandemics can help us better predict, understand, and prepare for future pandemics.