According to researchers, the British variant of coronavirus may have come from dogs

According to a study by Chinese scientists, a variant of the coronavirus that was first discovered in Britain may have come from dogs.

Shanghai-based researchers who tracked the early evolution of variant B117, which has caused a new wave of cases in several countries, did not find their footprint in viral samples collected from humans around the world.

But as they expanded their search to include animals, they discovered some early forms of B117 in dogs, including a sample taken in the United States last July.

“These progenitor variants comprised most or all of the mutations of the first B117 variant within populations of the Canidae family, and may have returned to humans after a period of rapid mutation,” Professor Chen wrote. Luonan and colleagues at the State Cell Biology Laboratory in a peer-reviewed paper published on biorxiv.org last Friday.

The appearance of variant B117 has baffled researchers. After being isolated from two patients in Kent, south-east England and London last September, it quickly became the dominant strain in the UK and many other countries, spreading faster than previous strains.

Some experts believe the variant could have emerged from local communities under the selective pressure of antiviral drugs used during the pandemic. According to a dominant theory, it suddenly appeared in the UK and later spread to other parts of the world.

But the variant has nine different mutations that are rarely, if ever, found in previous human strains, according to Chen and colleagues.

These mutations did not occur in adjacent genes, but spread sparsely throughout the viral genome. The probabilities of all these mutations occurring at once are extremely low.

The Shanghai team believes these nine mutations are piling up one after the other. His model suggested that the variant could originate outside the UK and acquire mutations in a non-human host. Dogs were the most likely suspects, followed by minks or cats.

Qu Liandong, a professor of virology at the Harbin Veterinary Research Institute who did not participate in the study, said more solid evidence would be needed to substantiate the theory.

The strains found in dogs were not quite the same as those first identified in the British patient. Although the number of genomic sequences obtained by researchers worldwide has reached hundreds of thousands, it is small compared to the total number of patients there.

Some early forms of the B117 variant may be missing with sampling programs, according to Qu.

But if pets like dogs turn out to be the host, “we’ll have a big problem,” said Qu, who studies infectious diseases shared by humans and animals.

“Almost all our measures to combat the pandemic so far are only considered by humans. If animals are involved, the game will change completely, ”he said.

When bird flu breaks out on a chicken farm, all chickens must be killed, according to world standard practices. If the disease can infect humans, all susceptible animals, including healthy ones, should be removed to the affected area.

Dogs are important human companions, but if they were shown to be able to carry or produce mutated variants of the Sars-CoV-2 virus, they could also be eliminated, Qu said.

An alternative is to administer vaccines to animals. “But we can’t give dogs human vaccines. We may need to develop some completely new versions. We are already fighting to vaccinate humans. How can the program be expanded to include dogs or other animals? “What added.

There are growing concerns that B117 can cause a lot of harm to dogs. Veterinarians near London noticed a sudden increase in pets (including dogs and cats) suffering from myocarditis, a serious heart condition earlier this year, and many of those animals tested positive for the variant, according to a Reuters report in March.

Humans and animals have different immune systems and it is often difficult for a virus to jump from one species to another.

The Sars-CoV-2 virus is thought to have originated in bats, but it may have taken decades to adapt to humans. When and where he made the leap from animals to humans is still unclear.

Chen’s team said the B117 variant had a unique evolutionary strategy to increase its infection, so it can be spread more easily from one host to another, but at the same time it reduces the number of copies it makes in one. host.

According to the researchers, if this strategy helped the variant bridge the species gap, more needs to be studied.

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