Snakes Could Be the Original Source of the New Coronavirus?

Sep 26, 2024

Snakes Could Be the Original Source of the New Coronavirus?

The outbreak of the coronavirus in mainland China's Guangdong province has scientists wondering about the origins of the disease and looking for animals that may have transmitted it to humans. 🤔

The disease that has sparked a global alarm was first reported in late December 2019 in Wuhan, a major city in central China, and spread rapidly 🗺️. Since then, sick travelers from Wuhan have infected people in China and other countries, including the United States and France.

Snakes (the Chinese krait and cobra) may be the vector for the coronavirus that sparked the endemic outbreak of the deadly infectious respiratory disease in China, according to a new study published in the Journal of Medical Virology. However, some researchers remain skeptical of this claim.

Is the snake 🐍 the cause of the 2019 Coronavirus? Fact or fiction, go to the end of this article to find out!

1) What is a Coronavirus?

Before getting to the heart of the matter, it seems relevant to us to make a quick reminder about this virus.

A) A virus already known

Using samples of the Wuhan virus isolated from patients, scientists in China determined the genetic code of the virus, and used microscopes to photograph it 🔬. The pathogen responsible for this epidemic is a new coronavirus. It is part of the same family of viruses as the well-known severe acute respiratory syndrome coronavirus (SARS-CoV) and the Middle East respiratory syndrome coronavirus (MERS-CoV), which have killed hundreds of people over the past 17 years. The World Health Organization (WHO) has named the new coronavirus 2019-nCoV.

The name coronavirus comes from its shape, which resembles a crown 👑 or the solar corona when imaged using an electron microscope. The electron microscope image reveals structural details of the crown shape for which the coronavirus was named.

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B) A dangerous disease with no real cure

Coronavirus is highly contagious and is transmitted through the air. It primarily infects the upper respiratory tract and gastrointestinal tract of mammals and birds. Human-to-human transmission of this virus is facilitated by coughing fits that produce saliva, and sweat droplets 😷.

While most members of the coronavirus family cause only mild flu-like symptoms during infection, SARS-CoV and MERS-CoV can infect the upper and lower respiratory tract and cause severe respiratory illness and other complications in humans.

This new 2019-nCoV causes symptoms similar to SARS-CoV and MERS-CoV. People infected with these coronaviruses experience a severe inflammatory reaction and acute fever 🤒 once the incubation period is over.

Unfortunately, there is no vaccine or approved antiviral treatment for coronavirus infection. A better understanding of the life cycle of 2019-nCoV, including the source of the virus, its mode of transmission, and its replication, is needed to prevent and treat the disease 💊.

2) Zoonotic Transmission

A) Animal-to-Human Transmission of Coronavirus

Both SARS and MERS are classified as zoonotic viral diseases, meaning that the first patients who were infected acquired these viruses directly from animals 🦇. This was possible because, in the host animal, the virus acquired a series of genetic mutations that allowed it to infect and multiply in humans.

Today, these viruses can be transmitted from one person to another, facilitating de facto contamination between humans mainly through fluid contact. Field studies have revealed that the original source of SARS-CoV and MERS-CoV is the bat, and that masked palm civets (a mammal native to Asia and Africa 🌍) and camels or dromedaries (species of camelids), respectively, served as intermediate hosts between bats and humans.

B) Wuhan Market Origin of China Outbreak

In the case of this 2019 coronavirus outbreak, reports indicate that the first case and most of the first group of hospitalized patients were workers or customers at a local seafood market that also sold processed meats and live consumable animals 🤢, including poultry, donkeys, sheep, pigs, camels, foxes, badgers, bamboo rats, hedgehogs, and reptiles. However, since no one has ever reported finding a coronavirus infecting aquatic animals, it is very plausible that this coronavirus could have originated from the land animals sold at this market.

The hypothesis that 2019-nCoV originated from an animal sold at the Wuhan market is strongly supported by a new publication in the Journal of Medical Virology. Scientists are currently analyzing and comparing the genetic sequences of 2019-nCoV and all other known coronaviruses 🔎.

Knowing which animals carry the virus behind the new disease is critical to helping people protect themselves from exposure.

C) The two most likely sources of Coronavirus: bats and snakes

Study of the genetic code of 2019-nCoV reveals that the new virus is most closely related to two samples of SARS-like bat coronaviruses from China, initially suggesting that, like SARS and MERS, bats could also be the source of 2019-nCoV. The authors 👨‍🔬 also found that the viral RNA coding sequence of the 2019-nCoV spike protein, which forms the "crown" of the viral particle that recognizes the receptor on a host cell, indicates that the bat virus may have mutated before infecting people.

But when the researchers performed a more detailed bioinformatics analysis of the 2019-nCoV sequence, it suggested that this coronavirus may have originated in snakes.

3) Snake at the origin of the Chinese Coronavirus?

A) Snakes may be the intermediate host for 2019-nCoV

SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome) both originally emerged in bats. Then they moved to another animal, called an "intermediate host," before spreading to humans 💨. In the case of SARS, those animals were civet cats, while the intermediate hosts for MERS are camels.

For the 2019 novel coronavirus (currently called 2019-nCoV), scientists don’t yet know how humans contracted the disease. But a new study published on January 22 suggests that snakes may be acting as an intermediate host.

B) The origin of this belief: a paper published in the Journal of Medical Virology

A national task force of Chinese researchers working rapidly to isolate and sequence the virus in order to find a cure as soon as possible 🧫, shared a draft of its genome in a public database earlier this month.

This has allowed labs around the world to design diagnostic tests to spot cases spreading outside of China. To date, fewer than a dozen cases have been confirmed in other countries, including Japan, Korea, Singapore, Hong Kong, Thailand, Vietnam, and the United States.

The release of the genetic data has also sparked a wave of new research findings in recent days, including a paper published by a team of Chinese researchers in the Journal of Medical Virology that claims to have used the viral sequence to find the most likely source of the emerging outbreak. Their theory: snakes 🐍.

C) Analysis by the team of Chinese microbiologists led by Wei Ji

Wei Ji, a microbiologist at Peking University Health Science Center 👨🏻‍🔬, and his colleagues analyzed the codons used by 2019-nCoV. Codons, which are trios of DNA or RNA that dictate the amino acids in a protein, tend to be similar between a virus and the animal it infects. The team compared the codons of 2019-nCoV with those of potential “animal reservoirs,” including humans, chickens, bats, hedgehogs, pangolins, and two species of snakes (the Chinese krait and the Chinese cobra).

They reported finding the greatest overlap in codon bias between 2019-nCoV and these two kinds of snakes: the Chinese cobra and the multi-banded krait. Taken together, these results “suggest for the first time that snakes are the most likely wildlife reservoir for 2019-nCoV,” the authors wrote. “The new information gained from our evolutionary analysis is very important for effective control of the 2019-nCoV pneumonia outbreak.” Wei and his team suggest that a virus from the northern krait or Chinese cobra may have combined with a bat virus and triggered the new outbreak 🤔.

The northern krait (Bungarus multicinctus), also known as the Taiwanese krait or Chinese krait, is, like the Chinese cobra (Naja atra), a highly venomous red snake ⚠️ found across much of central and southern China and Southeast Asia.

4) Coronavirus: Bats or snakes?

A) Why the hesitation between these two vectors?

The researchers used an analysis of the protein codes 🧬 favored by the novel coronavirus and compared it to the same codes of coronaviruses found in different animal hosts, such as birds, snakes, marmots, hedgehogs, manis, bats, and humans. Surprisingly, they found that the protein codes of 2019-nCoV are very similar to those present in snakes.

Snakes often hunt bats in the wild. Reports indicate that snakes were sold in the local seafood market in Wuhan, raising the possibility that 2019-nCoV may have been transmitted from the host species (bats) to snakes and then to humans early in this coronavirus outbreak. However, how the virus was able to adapt to both cold-blooded and warm-blooded hosts remains a mystery 🤨.

The authors of the report and other researchers need to verify the origin of the virus through laboratory experiments. Looking for the 2019-nCoV sequence in snakes would be the first thing to do. However, since the virus emerged, the seafood market has been disinfected and closed ❌, making it difficult to find the source animal of the new virus.

B) Epidemiological analyses to find the origin of the 2019-nCoV coronavirus

Sampling viral RNA from animals sold at the market and from wild snakes and bats 🦇 is necessary to confirm the origin of the virus. However, the results obtained will also provide guidance for the development of prevention and treatment protocols.

The 2019-nCoV outbreak is another reminder that humans must limit the consumption of wild animals to prevent zoonotic infections.

Preliminary analyses of genetic data released by Chinese authorities suggest that 2019-nCoV is most closely related to a group of coronaviruses that typically infect bats. But for various reasons (including the fact that it is winter and bats are hibernating 😴) many scientists suspect that another animal transmitted the virus from bats to humans.

5) Snakes and Coronavirus: The scientific community is skeptical

A) The snake... A bad lead?

It is unlikely that the virus jumped from a reptile to a human ✋, says Edward Holmes, a virologist at the University of Sydney. "I can't say categorically that it has never happened," he says. "But the [animal] reservoirs of human viruses are mainly mammals and perhaps birds."

Animals are often the source of human disease outbreaks 🤒. Many recent and ongoing outbreaks are zoonotic, originating in animals, such as the Ebola outbreak in Africa (2014-2016) and the Zika virus that struck the Americas in 2016.

Scientists are leaning more towards bats than snakes as the explanation for the origin of the coronavirus 👩🏼‍🔬. Among other things, bats are believed to be the source of Ebola and Zika from animals to humans.

B) The new virus is transmitted by a mammal

But “coronaviruses tend to be found in mammals, not reptiles,” says David Robertson, a virologist at the University of Glasgow in Scotland. So it’s unlikely that the new virus came from snakes, he says ⛔.

Robertson and Holmes say the study’s data don’t match the findings of the Chinese team led by Wei Ji. The genetic results seem to suggest that the virus came from bats, not snakes, the two scientists say.

Researchers should test animals sold in the market where the outbreak began, looking for closely related viruses 🔎, Holmes says. Finding the virus itself or antibodies to it in animals is the gold standard for virologists to determine where the virus that caused an outbreak came from.

And determining the source of the virus is a step toward protecting people from contact with other infected animals.

“Coronaviruses are definitely in bats, and there’s very likely a mammalian intermediate host [for the new virus], but we haven’t discovered it yet,” Robertson says. “So people shouldn’t start killing snakes, that would be a terrible thing.” 😕

6) The Snake Behind Coronavirus: Fact or Fiction?

A) The Speed of Sharing Scientific Information at Issue

Sharing data during an outbreak is vital for public health and the speed of research 🖥️. But it can also lead to sensational, even spurious, research, like a controversial new paper claiming that people likely caught a novel coronavirus from snakes.

One of the many mysteries behind the emergence and transmission of the virus that has caused more than 40 deaths is where exactly it came from. Most of the patients have a connection to the Wuhan market. A humid place where people sell live and dead animals 💀, including exotic species, on tightly fitted stalls. So there is plenty of room for hasty interpretations and conclusions about suspected cases.

B) The “snake flu” myth debunked

Although nothing has been confirmed, epidemiologists suspect that the novel coronavirus was transmitted to humans by an animal present in the market, which has been closed since January 1. Finding the right viral culprit is crucial to preventing future cross-species contamination 😯. In 2003, when SARS emerged in the same region of China, the outbreak was not fully contained until civet cats, which had transmitted the virus to humans, were removed from the area’s markets.

After being amplified by a press release and a widely syndicated editorial written by three newspaper editors, stories of “snake flu” in China began to spread on social media, alongside official reports of newly confirmed cases. But most researchers believe this is probably not true. ❌

7) No, Snakes Did Not Cause 2019 Coronavirus

A) A “botched” study, a rushed paper

The claim that snakes caused the coronavirus outbreak “is bunk,” says Edward Holmes, a zoologist at the University of Sydney’s Institute of Infectious Diseases and Biosecurity who specializes in novel RNA viruses 🧬, a class that includes coronaviruses like 2019-nCoV.

Holmes, who also holds positions at the China CDC and Fudan University in Shanghai, is among many scientists who are pointing out what they consider to be major flaws in the paper 📰 on virology forums, science Slacks, and Twitter, and calling on the paper to retract its findings. “It’s great that the viral sequence data is being shared openly and in real time,” Holmes said. “The downside is that people then use that data to draw conclusions they shouldn’t. The result is just a really pointless distraction that smacks of opportunism.”

But there are a number of problems with Wei’s approach, Holmes says. First, comparing codon biases is a very indirect way to identify an animal host. Second, it works best when you look at species from very different angles of the taxonomic hierarchy 🤨. Plant and mammalian viruses have really distinct codon patterns.

The same is true for insect and bird viruses 🐔. But within more closely related groups, it’s much harder to see meaningful patterns, especially when the authors only sampled a few species. “There could easily be other species that are more similar than snakes, but we don’t know because they simply weren’t considered in the analysis,” Holmes says.

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B) Snakes ruled out in research

Holmes and others are also skeptical that snakes are the intermediate host, as there are no documented cases of reptiles harboring coronaviruses that can transmit to humans. Their cold-blooded biology is just too different 🙅‍♂️. 2019-nCoV, and its closest relative, SARS, belong to a subgroup known as beta-coronaviruses, which are known to infect only mammals.

“I’m not saying it can’t happen. It could. Nature does weird things,” says Nathan Grubaugh, an epidemiologist at the Yale School of Public Health whose lab specializes in using genomic data to track emerging diseases. But Grubaugh says there’s no evidence that it does 👎. “There’s as much reason for snakes to be the intermediate host as there is for me to say offhand that it’s birds,” he says.

8) Bottom Line

The editors of the Journal of Medical Virology said they’re standing by the publication, which they said underwent a formal peer-review process that found the authors’ methods to be sound. That process was expedited ⌚: reviewers were given 24 hours to comment and the authors were given three days to respond.

But given the need for public health information ⚕️, they believe the acceleration was appropriate. “With this serious situation, with people dying, it would be criminal to delay the publication of this article,” says Shou-Jian Gao, the journal’s editor-in-chief. “This is just to open up the scientific dialogue.” He invited any researchers with divergent assessments to submit them to the journal as written comments.

One thing everyone agrees on is that there is only one way to conclusively, definitively and undeniably establish which animal served as the bridge to humans: and that is to collect the blood 🩸 of every winged, webbed and scaled creature that was in the wet market and test it for the virus.

Finding antibodies would be a good clue 🔍, but live virus would be even better. Those investigations are currently underway, according to WHO (World Health Organization) and health officials who spoke at a press conference. Until they find something, guesses will remain just guesses.

Dive into the fascinating world of snakes and explore our other articles now!

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Snakes Could Be the Original Source of the New Coronavirus?

Snakes Could Be the Original Source of the New Coronavirus?