The monkeypox virus spreading in the US, Europe and the UK is mutating surprisingly quickly, according to a study conducted by Portuguese researchers and published in the journal Nature Medicine. The study offers the most in-depth look at the genetic makeup of the virus to date.
Scientists sequence viral genomes because the genome is the virus’s playbook—the genome is the genetic material of an organism, and in the case of a virus, it tells us what the virus is, what it does, and how it’s likely to spread.
Monkeypox has mutated 50 times since 2018
In the Portugal study, researchers took samples from 15 monkeypox patients and compared the genomes of the virus that infected them.
The researchers found that each of the patients had a strain of monkeypox that could be traced to a previous outbreak of the virus in 2018-2019 in the United Kingdom, Israel and Singapore, and which originated in Nigeria.
But more than that, their tests showed that the virus had mutated 50 times — up to 12 times more than they would have expected — since the previous outbreak in 2018.
“These data completely challenge what is known about the mutation rate of monkeypox,” said study author João Paulo Gómez, a researcher at Portugal’s National Institute of Health.
West African monkeypox has a lower mortality rate
There are a few things we know about monkeypox, and this new genome sequencing has helped researchers better understand the current epidemic.
First, the strain of virus in the current outbreak is mutating at an unusually rapid rate.
Second, the outbreak probably started with a single case infecting others at a large superspreader event.
The strain is part of the West African clade of monkeypox, which is frequently reported in western Cameroon and Sierra Leone and carries a mortality rate of less than 1%.
A clade is defined as a group of organisms that can be traced back to a common ancestor or common genetic lineage.
There is another common class of monkeypox, known as the “Central African” class, which is more common in the Congo Basin and has a mortality rate of up to 10%.
There are two main “clades” of monkeypox virus. The clade currently circulating in Europe and the US is the less lethal of the two, with a mortality rate of around 1%.
The incubation period of monkeypox makes tracking difficult
In addition, there is still much we do not know about monkeypox in the current outbreak.
Its incubation period, which ranges from five to 21 days, makes its movements difficult to track.
The World Health Organization identified the so-called “index case” – the first confirmed case – as one who had traveled from Nigeria to the US in early May.
But researchers in Portugal dispute that idea, as they say there were confirmed cases in Portugal and the UK as early as late April.
If the researchers in Portugal are right, we know less than we thought about the current epidemic, such as how it developed and what it is likely to do next.
So where did the monkeypox epidemic start?
The scientists wrote in their study that it is highly likely that the virus was imported from a country where monkeypox is endemic, such as Nigeria, but also said they could not rule out other possibilities.
They say it is also possible, for example, that the virus may have spread silently through humans and/or other animals to non-endemic countries, such as the UK or Singapore, after the 2018-2019 outbreak.
And, they say, it’s unclear whether the mutated version is worse than the original version.
“The authors describe an unexpectedly large number of mutations in the virus, but their implications for disease severity or transmissibility are unclear,” Hugh Adler, a researcher at the Liverpool School of Tropical Medicine, said in response to the paper. He did not participate in the research.
“We have not identified any change in the severity of clinical disease in patients diagnosed in the current outbreak,” said Adler, who has worked with monkeypox patients in the UK during previous outbreaks.
Monkeypox research ‘still in its infancy’
Monkeypox is a double-stranded DNA zoonotic virus. DNA viruses mutate more slowly than RNA viruses, such as the one that causes COVID-19.
But in general, we lack a lot of knowledge about monkeypox. Researchers in Portugal, for example, cited only one other study on the genetics of the virus.
Symptoms of monkeypox can appear on the skin as small red dots, but can also include flu-like symptoms such as headache and sore throat
Adler says research into the genetics of the virus is “still in its infancy.”
“We have the genome sequenced, so we have an idea of what the genes are,” Adler said. “But in terms of really understanding what they do and the implications for evolution if the genes change – there’s very little research done on that compared to a lot of the other big viruses that we know.”
Adler said the research by João Paulo Gómez’s team in Portugal has provided “fascinating” new insights into the biology of monkeypox, but Adler noted that the study appears to have only occurred because of the ongoing spread of the virus in hgh-income countries .
“As always, if the world community had applied these same scientific resources to [previous] monkeypox epidemics in Africa, we may now have a stronger knowledge base,” Adler said.
Monkeyox was first discovered in a monkey in 1958, and the first human case was found in a young child in 1970 in the Democratic Republic of the Congo.
Editing: Zulfikar Abani
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