Thread by @KellerZoe

A lab-grown early version of Covid-19 has been discovered in samples from a Chinese biotechnology firm. The finding lends weight to claims that the virus may have started life as a lab experiment that accidentally leaked out.
telegraph.co.uk/news/2022/02/0…

The variant has mutations that bridge the gap between bat coronavirus and the earliest Wuhan strain, so it may be an ancestral version of the virus. The samples also contain DNA from hamsters and monkeys, suggesting that the early virus may have been grown in animal cell lines.

Viscount Ridley, author of Viral: “The unique mutations hint at it being an ancestral variant. So if it was sequenced in say mid-December, before anybody had identified the virus in people and started trying to grow it in labs, then it points to secret samples in labs in 2019.”

Commenting on the animal DNA discovered, he said: “These are not from seals or penguins but from African green monkeys and Chinese hamsters. Both species are the source of commonly used laboratory cell lines.”

Sangon Biotech is frequently used by Chinese scientists for sequencing, including the Wuhan Institute of Virology, which some experts think is the most likely location for a leak. If the DNA extraction took place in Dec 2019, it could be the ancestor of the original Wuhan strain.

The closest natural relatives to Covid-19 have been found in bats. One, named RaTG13, was found in caves in Yunnan, several others (Banal 20 to 52) were discovered in Laos. Both areas were being studied by “virus hunters” with samples sent to the Wuhan Institute of Virology.

Describing the significance of the discovery, Dr Bloom said: “Those 3 mutations are all ancestral mutations that move the sequence ‘closer’ to the bat coronavirus relatives RaTG13 and Banal 20-52 relative to first reported Wuhan-Hu-1 sequence from the Huanan Seafood Market.”

In May 2021, a team of US evolutionary biologists published research on what an ancestor to Covid-19 should look like, and came up with two options. One had the same three mutations found in the samples.

“A virus with those 3 mutations is one of the two plausible progenitors for all currently known human SarsCov2s. The timeline matters a lot. If they were sequenced in Dec 2019 then it’s exceptionally important, because China holds SarsCov2s not discovered until December 30 to 31.