Scientists investigating the monkeypox outbreak are open to whether the virus mutated to be more easily transmitted among humans, it has emerged.
The possibility that the cluster of cases in the UK, Europe and other regions where it is not endemic was caused by “superspreader” events in Belgium and the Canary Islands is still a strong line of research.
But sequencing the monkeypox virus genome from this 2022 outbreak has revealed some mutations that may be linked to human-to-human transmission.
Experts stressed that it is too early to say whether the mutations have made the virus more transmissible, but it is being investigated as a possible factor.
The virus associated with this outbreak is not classified as a new variant, but rather as a sublineage of the existing variant that is endemic to West Africa.
Scientists at the Genomics and Bioinformatics Unit of the National Institute of Health Doutor Ricardo Jorge in Lisbon, Portugal identified mutations in genomic sequences from nine patients infected with the current monkeypox outbreak.
In a discussion on the forum virological.org, they describe “the first signs of microevolution within the outbreak cluster,” including seven genetic mutations.
There are also signs of gene deletion in the genomes of this outbreak, which could potentially indicate increased transmission, the Portuguese researchers said.
Aris Katzourakis, professor of evolution and genomics in the Department of Zoology at the University of Oxford, said: i it was too early to say whether the changes led to increased transmission. He said there were signs in the 2022 genomes of “hypermutation” caused by the host’s antiviral defenses.
He added: “It appears that in this case it is possible that this series of mutations allowed for an ‘evolutionary jump’ in these monkeypox sequences, causing them to diverge more than would be expected.
“We don’t know the functional consequences of this, but this certainly deserves research in light of the possibilities for adaptation to human-to-human transmission.
“It is known that large DNA viruses such as poxviruses can evolve relatively quickly through gene deletion, compared to the relatively slow process of sequence change.
“It’s not unreasonable to imagine that this deletion could be involved in human-to-human transmission, but not all monkeypox genomes sequenced to date seem to carry this.
“Basically, there are several lines of research to investigate whether these monkeypox genomes may be better adapted to human-to-human transmission.
“However, it is too early to say whether this is a certainty and to weigh this against the potential transmission benefit of joining a well-connected transmission group.”
Tom Wenseleers, a professor of evolutionary biology at the University of Leuven, Belgium, tweeted: “It remains an open question whether this new lineage could have a different transferability.
“If so, it might provide a sparse answer to the question, ‘Why are we seeing this international outbreak now?’, but several factors are likely contributing.”