First monkeypox genome from latest outbreak shows links to 2018 strain

The draft sequence of the virus responsible for the rapidly growing monkeypox outbreak shows it is most closely related to strains detected in the UK, Singapore and Israel in 2018 and 2019

By Michael Le Page

Electron microscope image of a monkeypox virus

CDC/Cynthia S. Goldsmith

The first draft genome of the virus responsible for the rapidly growing monkeypox outbreak has been released online by a team in Portugal. The DNA sequence shows it is of the mild West African type and most closely related to the monkeypox viruses detected in the UK, Singapore and Israel in 2018 and 2019.

What isn’t yet clear is whether this virus has any changes that make it more transmissible in humans, which would explain why the current outbreak is so widespread and by far the largest seen outside Central and West Africa, where the virus spreads in monkeys. This could take some time to establish, given that monkeypox has a large and complex genome.

At the time of writing, there were 127 confirmed and suspected cases of monkeypox in 10 countries, including the US, UK and Australia, and researchers suspect the true numbers are even higher.

João Paulo Gomes and colleagues at the National Institute of Health in Portugal sequenced a sample taken from a male patient on 4 May. Teams in other countries are also sequencing viral samples from the outbreak, but Gomes’s team is the first to make a sequence public.

Gustavo Palacios at Icahn School of Medicine at Mount Sinai, New York, says the draft sequence from Portugal has too many gaps to draw firm conclusions, but that he has seen a more complete sequence from a team in Belgium. “As far as I can see, it seems to be identical to the one in the UK in 2018,” says Palacios. “That is a little bit odd.”

In 2018, there were three cases in the UK after someone returning from Nigeria infected two other members of their household.

As more samples are sequenced, it should become clear whether, as suspected, a single variant of monkeypox is responsible for all the cases in the latest outbreak.

But establishing whether there is something unique about this variant won’t be easy. Even with the now very well studied SARS-CoV-2 virus, it is hard to link particular mutations to changes in viral transmissibility and so on. The monkeypox virus is much larger – around 200,000 DNA letters long compared with 30,000 RNA letters for the coronavirus – and for now at least not nearly as intensively studied.

“Further sequencing and analysis ongoing,” tweeted team member Vitor Borges.

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