COVID-19 virus unlikely to have come from bat virus alone

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  Last updated July 13, 2020 at 11:03 am


According to a new study, the SARS-CoV-2 virus that causes COVID-19 may be the result of two or more coronaviruses combining rather than a single coronavirus in bats.

SARS-CoV-2 virus_bats_bat

Credit: Tamara Lackey / Getty Images

Why This Matters: Finding the source of SARS-CoV-2 means we may be able to prevent future outbreaks.

Thought to be the likely source of the SARS-CoV-2 virus, which causes COVID-19, bats have copped a bit of bad press at the moment.

However, a new UK-led study published in journal Nature Structural & Molecular Biology suggests the SARS-CoV-2 virus, is likely to be the result of two or more coronaviruses combining, rather than having evolved from a single coronavirus in bats.

The paper focuses on the spike protein of SARS-CoV-2 – the protein that allows the virus to bind to human cells and cause COVID-19.

“In simple terms, the study compares the binding success of two virus proteins, SARS-CoV-2 and its closest known bat relative, RaTG13, to human cells,” Francesca Di Giallonardo from the Kirby Institute at UNSW Sydney told the AusSMC.

“SARS-CoV-2 binds very well, while the bat virus does not.”

Also: Bats are host to many deadly viruses – so how come they don’t get sick?

“The results showed that SARS-CoV-2 spike protein has a 1,000-fold higher binding capacity compared to the bat virus spike protein,” she adds. “It is highly unlikely that RaTG13 would be able to bind effectively to a human cell and thus establish an infection.”

Di Giallonardo says it is not surprising that the viruses behaved differently in tests, because they are “genetically different”, which is “to be expected due to natural selection in different hosts”.

Results add to the puzzle of the origins of COVID-19

Nikolai Petrovsky from Flinders University and Vaxine Pty Ltd told the Centre the findings support previous work done by his team, but also throw up questions about the origins of COVID-19.

“This just adds to the puzzle of the origins of the SARS-CoV-2 virus, and how it acquired its distinctive and pathogenic features,” he says.

Also: What we know (and don’t know) about the COVID-19 virus

The SARS-CoV-2 spike protein closely resembles a previously-identified pangolin coronavirus spike protein, says Petrovsky. “Without its pangolin-like spike protein…the SARS-CoV-2 virus could not have become a virulent human pathogen,” he adds.

But parts of the SARS-CoV-2 spike protein are not like those from pangolins, he said, deepening the mystery of the virus’s origins.

However, Petrovsky points out that the bat virus used in the study was not derived from nature. It “is a conceptual rather than proven real virus, as a virus corresponding to RaTG13 [the bat virus studied] has never been isolated and cloned”.

So, it “may itself be an artefact rather than a real virus, made up of sequences from different but related coronaviruses,” he says.

It’s critical to figure out how SARS-CoV-2 evolved “so that future pandemics with similar viruses can hopefully be prevented”.

You can read more expert comments here.

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About the Author

Joseph Milton
Joe Milton is an evolutionary biologist who, after studying the evolution of plants for ten years at various Scottish universities, made a move into journalism. Since then he has written for the Financial Times, Nature and New Scientist, among others. Joe joined the London Science Media Centre in 2010, where he was Senior Press Officer for Mental Health, before taking up the position of Senior Media Officer at the Australian Science Media Centre in July 2012.

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The Australian Science Media Centre (AusSMC) is an independent, not-for-profit service for the news media, giving journalists direct access to evidence-based science and expertise. We aim to better inform public debate on the major issues of the day by improving links between the media and the scientific community. The Centre works with journalists to help them cover science as well as identify the science angles in everyday news stories and works with the scientific community to help them interact more effectively with the media and ensure that their voices are heard on issues of national importance.

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