Genetic data from Wuhan posted online and then deleted without explanation lends support to the theory that the pandemic coronavirus transmitted to humans from wild animals, claims the researcher who identified them.

Florence Debard, an evolutionary biologist at France’s National Center for Scientific Research, told a WHO meeting that samples from the central market in Wuhan, the epicenter of the pandemic, contained genetic material of SARS-CoV-2 along with genetic material from mammals now known that they are easily infected by the virus.

Debard believes the presence of infected animals in the Wuhan market lends support to the zoonotic theory, its website says Science.

In other words, the new findings weaken the scenario of the virus leaking from the Wuhan Laboratory of Virology, a scenario that a minority of scientists insist on.

The samples in question had been collected from market stalls by the team of George Gao, the former head of China’s Centers for Disease Control and Prevention.

Debard located the genetic sequences of the samples in GISAID, an international virus database, and informed her colleagues studying the origin of SARS-CoV-2. But when they contacted Gao to ask for their cooperation in analyzing the data, the sequences were deleted from the database.

Gao was contacted by Science, but he did not elaborate on why the data was downloaded from GISAID. He said, however, that the sequences do not answer the big question about the origin of the coronavirus, which remains open, he said.

It remains unclear what Gao’s motives might be, but it appears the Chinese researcher does not believe the virus came from animals: his team’s study presented last year as pre-publication reported that samples from the market contained genetic material of the virus along with human genetic material, without DNA from other animals.

Debard now hopes Gao will revise the pre-publication to include all sequences from the market.

Illegal trade

The samples in question were taken shortly after the Wuhan market was closed in January 2021 and contained genetic material from night owls, midges and other wild animals, whose trade was illegal. China persisted in denying that live mammals were being sold on the market until June 2021, when a study was published documenting the illegal trade.

As Gao told Science, “it was known that there were illegal transactions with animals, and that’s why the market was immediately closed.”

The question remains open

What is certain, however, is that the sequences in question, even if they confirm that infected animals were indeed sold in the market, do not offer a definitive answer to the mystery.

For example, proponents of the laboratory spillover theory might conclude that market animals were contaminated by humans.

Many scientists also believe that the leakage theory is simply impossible to confirm or disprove.

As Joel Wertheim of the University of California, San Diego, who believes in the zoonotic theory and now works with Debard, “you can’t directly observe the transmission of a new virus from animals to humans.”

“We will never have data of this level,” he said.