Several years ago, researchers searched for the remains of 1867 people who lived between 30,000 and 150 years ago for genetic traces of smallpox virus, which can cause smallpox. Among the teeth and bones of four Nordic people from the Viking era, they found enough DNA to reconstruct the entire smallpox genome. The sequenced virus is not the direct ancestor of the terrible smallpox strain that was eradicated in the second half of the 20th century. But they may have grasped the clues about how smallpox became so deadly.
Researchers reported in a 2020 paper published in the journal Science that over 350 years, the Viking virus lost several genes. Researchers have seen this pattern before. Modern smallpox viruses have also recently lost several genes, although due to different mutations. Seeing it twice “shows that the gene loss is not accidental,” said Antonio Alcamí, a poxvirologist at the Severo Ochoa Center for Molecular Biology in Madrid. “It was chosen.” Alcamí believes the loss could make the smallpox virus more toxic, resulting in its 30% mortality rate. In the past, smallpox could have been a "widely spread mild disease," he wrote in a comment accompanying the paper.
Now, some scientists want to know: Will such a thing happen again?
Since May, a cousin monkeypox virus, which is far less fatal than , has been spreading worldwide, giving the virus an unprecedented opportunity to change and adapt to the human population. Will it evolve into more contagious or lead to more severe illness?
No one knows, but the recent history of SARS-CoV-2 provides a thought-provoking lesson. After the virus emerged in Wuhan at the end of 2019, it first produced a series of variants that may have spread much faster than its progenitor cells and then evolved further to escape human immunity. Its tricks even surprised some scientists who have long studied virus evolution. evolutionary virologist Aris Katzourakis, Oxford University, said SARS-CoV-2 shows that "if a new virus enters a space without immunity, rapid adaptation occurs."
Monkeypox can bring equally unpleasant surprises to humans. In July, researchers in Berlin published a preprint that analyzed the viral genome sequences found in skin lesions in 47 monkeypox patients. In addition to many small changes, they discovered a virus in which one of the complete genes was copied and the other four disappeared completely. The last paragraph of this paper reads almost like a warning: "The results of changes in the poxvirus gene are no longer needed or otherwise altered in a new host environment, and the results are unpredictable," said the author. “The [monkeypox virus] phenotype we know in the last 64 years may be different from recent humans” monkeypox.
Many researchers say we should not be too worried now. Poxvirologist Jeffrey Smith at the University of Cambridge doubts whether monkeypox virus will easily become a more toxic version. It is well known that the large number of poxviruses evolved at a slow rate, and they did not easily adapt to evade the epidemic, which did just as cleverly as SARS-CoV-2. SARS-CoV-2 is a highly contagious respiratory pathogen that infected hundreds of millions of people in the first year; monkeypox is mainly spread among men and men, and has reported only about 60,000 cases so far, so its chances of evolution are much smaller.
However, this may change. A "bad situation" is that the virus evolves faster to replicate in humans, says Bernard Moss, a senior poxvirus researcher at the National Institute of Allergy and Infectious Diseases. This will allow it to infect more people, which in turn will accelerate its evolution and potentially make it better at infecting people.
At present, monkeypox virus is not very good at infecting humans. It is a versatile and seems to thrive in a range of animal species in sub-Saharan Africa, most of which are rodents. The virus sometimes spreads to people and sometimes infects some other people. Despite the increasing frequency of outbreaks in recent years, they are usually small. After each appearance, the virus obviously disappeared from the crowd again.
This time is different because monkeypox continues to spread from person to person in the global outbreak. "We have never seen this virus have such a great opportunity to adapt to humans before," said Terry Jones, a computational biologist at the Charleston University Hospital in Berlin and one of the authors of the July preprint.
Note: Mutations observed in monkeypox samples allowed researchers to trace the root causes of the current outbreak starting from Nigeria . The virus was exported to other countries many times and eventually spread to all parts of the world. Since human protein APOBEC3 may introduce many mutations, they can also show how long the virus has been spreading in humans.
For more information about "monkeypox", please click to read:
Monkeypox has been declared a global emergency: Will the epidemic be controlled?
Can the global monkeypox epidemic be curbed? There are many challenges in the future!
Monkeypox epidemic broke out around the world! Scientists are solving four key problems
This article is compiled from: Science
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