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Monkeypox Has Undergone “Accelerated Evolution”, Mutating At Unprecedented Rates

The ongoing monkeypox outbreak is unprecedented. This research could help to explain why.


Tom Hale

Senior Journalist

clockJun 27 2022, 11:41 UTC
Monkeypox virus under microscope.
Under a magnification of 125X, this image depicted a section of skin tissue, harvested from a lesion on the skin of a monkey that had been infected with monkeypox virus. Image credit: CDC

The monkeypox virus (MPXV) has recently mutated at a far faster rate than scientists would typically expect, which could potentially explain the ongoing explosion of cases in the parts of the world where the virus doesn’t usually thrive. 

New research, published in the journal Nature Medicine, suggests that the MPXV has recently embarked on an “accelerated evolution” at a rate that's surprised some scientists. 


Researchers from the National Institute of Health Doutor Ricardo Jorge in Portugal looked at the DNA of the current MPXV strain behind the ongoing outbreak.

The team explains that the current strain is closely related to the strain responsible for a 2018-19 outbreak in Nigeria. However, it has since undergone 50 mutations. It’s also undergone even more mutations during the recent outbreak via human-to-human transmission, picking up a further 15 minor variants and gene deletions.

At least 4,119 cases of monkeypox have been reported so far, primarily in Europe and North America. Considering the virus doesn't usually spread far beyond West and Central Africa where it is endemic and can be passed on from infected rodents, the outbreak has taken many experts by surprise. 


Just as its name suggests, the monkeypox virus is closely related to the viruses that caused smallpox (variola viruses). The genetic “instructions” used by these viruses to make copies of themselves come in the form of double-stranded DNA, just like us, other animals, and plants. However, this is unlike other viruses, like coronaviruses, that use single-stranded RNA. 

Small RNA viruses mutate relatively quickly (if COVID-19 has taught us anything about RNA viruses, it’s that they can pump out variants at a very troublesome rate). On the other hand, larger DNA viruses are comparatively slow at mutating, which is partly why these recent findings are so unexpected.  

“This report supports the prevailing hypothesis about the current outbreak: a single imported case, amplified through one or more super-spreader events,” Dr Hugh Adler, Department of Clinical Sciences at Liverpool School of Tropical Medicine who wasn’t directly involved in the new study, said commenting on the paper. 


“The authors describe an unexpectedly high number of mutations in the virus, but their implications for disease severity or transmissibility are unclear. We have not identified any change in the severity of clinical disease in patients diagnosed in the current outbreak,” he continued.

“We are seeing fascinating insights into the biology of monkeypox now that it has caused an outbreak in high-income countries – but as ever, if the global community had applied these same scientific resources to monkeypox outbreaks in Africa, we might already have a stronger knowledge base."

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