Stop Blaming Snakes For The Wuhan Coronavirus!

Dr. Adrian Wong

3 years ago

Many in the press have mistakenly identified snakes as the original source for the Wuhan coronavirus (2019-nCov), but that’s based on a flawed understanding of early research by Chinese scientists.

Find out what those Chinese scientists discovered, and why snakes are not the source or origin of the Wuhan coronavirus!

This article is a summary of the article – Why Snakes Are Not Source Of Wuhan Coronavirus! – simplified for easier understanding.

Claim : Wuhan Coronavirus Originated From Snakes

Every report that the Wuhan coronavirus originated from snakes is based on a single paper by Wei Ji et. al. published in the Journal of Medical Virology on 22 January 2020.

Wei Ji’s team analysed the Wuhan coronavirus, and discovered that it favoured codons (RNA instructions) that are most similar to those used by two snakes :

Bungarus multicinctus (the many-banded krait), and
Naja antra (the Chinese cobra)

They therefore concluded that “snakes could be the most likely wildlife animal reservoir for the 2019-nCoV“.

However, their paper is merely suggestive, not conclusive. Like other scientific papers, it was published for other scientists to check, criticise or verify their findings.

Now, let’s show you why snakes are very, very unlikely to be the source or even a host for the Wuhan coronavirus, in spite of what they discovered…

Why Snakes Are Unlikely To Be Source For Wuhan Coronavirus

Reason #1 : 2019-nCov Is A Betacoronavirus

The Wuhan coronavirus (2019-nCoV) has been confirmed to be a Betacoronavirus, which mainly infects bats.
Many Betacoronaviruses like SARS have been traced to bats.

Reason #2 : 2019-nCoV Is Most Closely Related To SARS

The Wuhan coronavirus is most closely related to two SARS-like coronaviruses of bat origin.
The human SARS virus was traced to horseshoe bats living in a remote Yunnan cave.
Hence, bats are likely to be the origin of the Wuhan coronavirus, not snakes.

Reason #3 : Coronaviruses Infect Only Mammals + Birds

Coronaviruses have, so far, been able to only infect mammals and birds. Basically, they are “warm-blooded” viruses.
It would be very unlikely for 2019-nCoV to evolve to infect snakes, which are cold-blooded reptiles.

Reason #4 : Only Mammals Have Been Intermediate Hosts

SARS and MERS, both Betacoronaviruses as well – spread to humans through mammals – civet cats and camels.
As such, the intermediate host for 2019-nCov is much more likely to be a mammal, rather than a reptile.

Reason #5 : Codon Adaptation Does Not Always Happen

Codon adaptation happen by chance through genetic mutation, so it does not always happen
Multiple codons also code for the same amino acids, so viruses can have different codon preferences than its host
Some viruses choose to use different codons from their host to avoid triggering the immune system or kill the host too quickly
That is why the Wei Ji team’s findings are suggestive, and not conclusive.

Reason #6 : Codon Adaptation Takes Time

It takes a long time for viruses to evolve to adapt to the host’s codon preferences, and would therefore be detectable in the wild snake population.
However, no one has been able to even verify it existed in snakes at the Wuhan Huanan seafood market, or even in the wild snake population

Reason #7 : Two Antigenic Shifts Are Very Unlikely

Viruses are known to mutate rapidly through small changes called antigenic drift.
In rare instances, they can “mate” with other viruses to create a completely new virus – a process called antigenic shift.
For the Wuhan coronavirus to evolve enough to “jump” from bats (or some other mammal) to a snake, and then evolve again to “jump” to a human host – it would be like getting struck by lightning… twice.

What Do Experts Say About Snakes As Wuhan Coronavirus Source?

Paulo Eduardo Brandão, virologist at the University of São Paulo, said,

They have no evidence snakes can be infected by this new coronavirus and serve as a host for it. There’s no consistent evidence of coronaviruses in hosts other than mammals and Aves (birds).

Professor Guizhen Wu, Chinese Center for Disease Control and Prevention, said,

These data are consistent with a bat reservoir for coronaviruses in general and 2019-nCoV in particular.

Dr. Peter Daszak, President of EcoHealth Alliance, said,

When you look at the genetic sequence of the virus, and you match it up with every known coronavirus, the closest relatives are from bats

Cui Jie, virologist at the Pasteur Institute of Shanghai, said,

Clearly this 2019-nCov is a mammalian virus.

We should note that Cui Jie was part of the team that traced the origin of the human SARS virus to the horseshoe bats in a remote Yunnan cave in 2017.

But Could Snakes Still Be Responsible For The Wuhan Coronavirus?

Now this is important – no one should rule out snakes as an intermediary host for the Wuhan coronavirus just yet.

Yes, there is no known coronavirus that infects a snake or any other reptile, but that doesn’t mean it will never or could not happen.

The key thing is to understand that science isn’t straightforward. It takes many studies – blood, sweat and tears – to investigate, verify and replicate – before we can reasonably draw a conclusion.

So everyone should stop jumping on every study as if it is conclusive evidence that snakes or civet cats or the animal of the week is responsible for the Wuhan coronavirus.

Rome wasn’t built in a single day, and evidence that conclusively identifies the culprit for 2019-nCov won’t be found in a single study.

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Claim : Wuhan Coronavirus Originated From Snakes

Why Snakes Are Unlikely To Be Source For Wuhan Coronavirus

What Do Experts Say About Snakes As Wuhan Coronavirus Source?

But Could Snakes Still Be Responsible For The Wuhan Coronavirus?

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