At the beginning of the 2000s, a coronavirus that infects bats jumped into procione dogs and other wild mammals in south -western China. Some of those animals were sold in the markets, where the Coronavirus jumped again, in humans. The result was Pandemia Sars, which spread in 33 countries and caused 774 lives. A few months, scientists discovered the crownavirus in mammals known as Palm Wests sold in a market in the center of the epidemic.
In a study published on Wednesday, a team of researchers compared Sars' evolutionary history with that of Covid 17 years later. The researchers analyzed the genomes of the two coronavirus who caused the pandemics, together with 248 coronavirus related to bats and other mammals.
Jonathan Pekar, an evolutionary virologist of the University of Edinburgh and an author of the new study, said that the stories of the two Coronavirus followed parallel paths. “In my mind, they are extraordinarily similar,” he said.
In both cases, they support Dr. Pekar and his colleagues, a Coronavirus jumped from bats to wild mammals in south -western China. In a short period, wildlife traders brought hundreds of miles infected animals into the city markets and the virus caused chaos in humans.
“When you sell wild fauna in the heart of the cities, you will have a pandemic every now and then,” said Michael Werobey, an evolutionary biologist at the University of Arizona and author of the new study.
The study lands in a political moment fraught. Last month the White House created a web page called “Lab Leak: The True Origin of Covid 19”, stating that the pandemic had not been caused by a discovered on the market but by an accident in a laboratory in Wuhan, in China.
On Friday, in his proposed budget, the White House described the laboratory loss as “confirmed” and justified a cut of $ 18 billion at the National Institutes of Health in part on what he described as “inability of the agency to demonstrate that his subsidies to the Wuhan Institute of Virology were not complicit in a possible loss”.
The Chinese government responded with a flat negation that Covid had been caused by a laboratory loss of Wuhan and raised the possibility that the virus had come instead from a biodephyne laboratory in the United States.
“An in -depth and in -depth investigation on the origins of the virus should be conducted in the United States”, reads the declaration.
Sergei Pond, Virologist of Temple University, said he had not considered the origin of Covidid established. But he feared that the incendiary language of the two governments would have made it difficult for scientists to investigate – and discuss – the origin of Covid.
“If it weren't tragic, you should laugh, it's so farcles,” said dr. Pond.
In the first weeks of the pandemic hood at the beginning of 2020, the statements circulated that the responsible virus, Sar-Cov-2, was a biological weapon created by the Chinese army. A group of scientists who analyzed the data available at the time rejected this idea. Although they could not exclude an accidental laboratory loss, they favored a natural origin of Covid.
Over time, Dr. Worobey, who was not part of that group, became frustrated by the fact that there were still enough evidence to choose one theory on the other. He signed an open letter with 17 other scientists asking for further investigations to determine what explanation was more likely.
“For us it seemed that there were many things we don't know, so let's not discard the idea of the laboratory,” said dr. Woobey. “Let's study it.”
While Dr. Werobey and other scientists began to study the origin of Covid, even American intelligence agencies were evaluating it. Their evaluations were mixed. The FBI and the CIA favor an escape from the Wuhan Institute of Virology, although with only low certainty. The Energy Department relies on little trust for the virus that escapes from a different laboratory to Wuhan. Other agencies rely on a natural origin.
Agencies have not made their tests or analysis public and therefore scientists cannot evaluate the foundations of their conclusions. However, Dr. Werobey and other researchers have published a series of articles in scientific journals. Along the way, Dr. Wobey was convinced that Pandemia Covidi had started at the Huanan seafood market in Wuhan.
“Scientifically, it is clear how HIV or Spanish influence,” said dr. Worebey, referring to two diseases whose origins also studied.
For the new study, Dr. Werobey, Dr. Pekar and their colleagues compared the genomes of 250 Coronavirus, using their similarities and genetic differences to determine their relationships. They were able to reconstruct the history of the crownavirus that cause both SAR and Covid, known as Sars-Cov and Sars-Cov-2.
The ancestors of both coronavirus circulated in bats in most of China and neighboring countries for hundreds of thousands of years. In the last 50 years, their direct ancestors infect bats who lived in the south -ovest of China and northern Laos.
While the Coronavirus infected the bats, sometimes they ended up inside a cell with another coronavirus. When the cell has created new viruses, it accidentally created hybrids that transported genetic material from both original criminalus – a process known as recombination.
“These are not ancient events,” said David Rasmussen, a virologist of North Carolina State University who has not been involved in the new study. “These things are always happening. These viruses are really mosaics.”
In 2001, just a year before the start of the pandemic of the Sars in the city of Guangzhou, the researchers discovered, Sars-Cov suffered his last genetic mixing in bats. Only after that last recombination did the virus evolved into a human pathogen. And since Guangzhou is several hundred miles from the ancestral region of Sars-Cov, the bats would not have been able to bring the virus to the city in such a short time.
Instead, researchers generally agree, the ancestors of wild mammals infected with Sars-cov who were subsequently sold in the markets around Guangzhou. A few months after the start of the Pandemia della Sars, the researchers discovered Sars-Cov in Palm Whotets and other wild mammals for sale in the markets.
The researchers found a similar model when they turned to Sars-Cov-2, the cause of Covid. The latest recombination in bats took place between 2012 and 2014, only five or seven years before the Covidi pandemic, several hundred miles north -east, in Wuhan.
That was also a substantial departure from the region in which the ancestors of the virus were circulated. But it was comparable to the journey that Sars-Cov has undertaken, courtesy of the wildlife trade.
The supporters of the laboratory theories highlighted the long distance between Wuhan and the positions in which the closest relatives of Sars-Cov-2 were found. If the bats could not fly in the region around Wuhan and infect wild mammals there, then they maintain scientists must have collected the coronavirus from bats in the south -ovest of China and filed with it in their laboratory, from which it fled.
American scientists criticized the Wuhan Institute of Virology for laxian guarantees in their experiments in Coronavirus. But nobody offered evidence of the fact that the progenitor of Sars-Cov-2 was at the Wuhan Virology Institute in front of the pandemic. The new study by Dr. Wobey and his colleagues shows that Coronavirus Bat can travel long distances without the help of scientists, through the trade in wildlife.
The researchers argue that these results agree with the studies they published in 2022, which indicated the Huanan seafood market in Wuhan as the place where the cooked pandemic began. Wild mammals were sold there; Many first cases of Covid were recorded there and Chinese researchers collected several Sars-Cov-2 strains that transported distinct mutations there. Dr. Wobey and his colleagues claimed that the virus had poured twice from wild mammals to the market.
Dr. Pond said that the new study was consistent with the theory of a spillover of the wildlife. But does not consider the question resolved. He noticed that last year two statistics questioned the model behind the 2022 study. Dr. Wobey and a colleague contrasted this criticism. “That debate is still in progress,” said dr. Pond.
Marc Eloit, former director of the Patogen Discovery Laboratory of the Pasteur Institute of Paris, said that the new study was significant to provide a clear picture of where Sars-Cov-2 comes from.
But he also observed that Coronavirus was considerably different from his closest relatives in bats. After he separated from those viruses, he must have changed or recombinated to become well adapted for spreading in humans.
“I believe that the possibility of a recombination event – both accidental and deliberated – in a laboratory environment remains plausible as the hypothesis of the emergency through an intermediate guest on the market”, said dr. Eloit.
Dr. Eloit and other scientists agreed on the fact that finding an intermediate form of Sars-Cov-2 in a wild mammal would have made a convincing case for a natural burst. The Chinese authorities looked at some animals at the beginning of the pandemic and did not find the virus in them.
However, wildlife sellers in the Huanan market removed their animals from stalls before scientists could study them. And once China has stopped the sales of wildlife, farmers hit their animals.
“There is a great missing piece, and you can't really dance it,” said Dr. Pond.
Stephen Goldstein, a geneticist at the Utah University who was not involved in the new study, said that the research was a warning on the risk of a future Pandemia di Coronavirus. Wild mammals sold in the markets anywhere in the region where Sars and Covid started could become a vehicle in a city of hundreds of miles away. “The pieces of these viruses exist in all these places,” said dr. Goldstein.