EXPERT REACTION: Could new coronavirus have come from snakes?

Embargoed until: Publicly released:

The novel coronavirus, 2019-nCoV, may have come from snakes, according to an evolutionary analysis of the virus. Researchers compared the genetic information of the virus with information already available on other viruses, and found that 2019-nCoV appears to have formed from a combination of a coronavirus found in bats, and another coronavirus of unknown origin - which turned out to be snakes. The unique mix of proteins changed the shape of the receptors that allow the virus to bind onto and infect cells. Researchers say this recombination may have allowed cross-species transmission from snakes to humans. The study notes that patients infected with the virus were exposed to animals at a wholesale market, where seafood, poultry, snakes, bats and farm animals are sold.

Journal/conference: Journal of Medical Virology

DOI: 10.1002/jmv.25682

Organisation/s: Griffith University, The University of Adelaide, Edith Cowan University, The University of New South Wales, The Australian National University, University of South Australia, Murdoch University, Peking University, China

Funder: This work was supported by Project of Guangxi Health Committee (No. Z20191111) and Natural Science Foundation of Guangxi Province of China (No. 2017GXNSFAA198080) to Dr. Xiaofang Zhao. This study was sponsored by K.C. Wong Magna Fund in Ningbo University.

Media Release

From: Wiley-Blackwell

Researchers Trace Coronavirus Outbreak in China to Snakes

Emerging viral infections—from bird flu to Ebola to Zika infections—pose major threats to global public health, and understanding their origins can help investigators design defensive strategies against future outbreaks. A new study published in the Journal of Medical Virology provides important insights on the potential origins of the most recent outbreak of viral pneumonia in China, which started in the middle of December and now is spreading to Hong Kong, Singapore, Thailand, and Japan.

Wednesday, January 22, 2020 12:22 pm EST

"Results derived from our evolutionary analysis suggest for the first time that snake is the most probable wildlife animal reservoir for the 2019-nCoV"

Emerging viral infections—from bird flu to Ebola to Zika infections—pose major threats to global public health, and understanding their origins can help investigators design defensive strategies against future outbreaks. A new study provides important insights on the potential origins of the most recent outbreak of viral pneumonia in China, which started in the middle of December and now is spreading to Hong Kong, Singapore, Thailand, and Japan. The findings are published early online in the Journal of Medical Virology.

The study notes that patients who became infected with the virus—which is a type of virus called a coronavirus and was named 2019-nCoV by the World Health Organization—were exposed to wildlife animals at a wholesale market, where seafood, poultry, snake, bats, and farm animals were sold.

By conducting a detailed genetic analysis of the virus and comparing it with available genetic information on different viruses from various geographic locations and host species, the investigators concluded that the 2019-nCoV appears to be a virus that formed from a combination of a coronavirus found in bats and another coronavirus of unknown origin. The resulting virus developed a mix or “recombination” of a viral protein that recognizes and binds to receptors on host cells. Such recognition is key to allowing viruses to enter host cells, which can lead to infection and disease.

Finally, the team uncovered evidence that the 2019-nCoV likely resided in snakes before being transmitted to humans. Recombination within the viral receptor-binding protein may have allowed for cross-species transmission from snake to humans.

“Results derived from our evolutionary analysis suggest for the first time that snake is the most probable wildlife animal reservoir for the 2019-nCoV,” the authors wrote. “New information obtained from our evolutionary analysis is highly significant for effective control of the outbreak caused by the 2019-nCoV-induced pneumonia.”

An accompanying editorial notes that although the ultimate control of emerging viral infections requires the discovery and development of effective vaccines and/or antiviral drugs, currently licensed antiviral drugs should be tested against the 2019-nCoV.

Expert Reaction

These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.

Professor Nigel McMillan is the Director in Infectious Diseases and Immunology at Menzies Health Institute Queensland, Griffith University

The story is rapidly developing with cases going to over 500 last night and deaths rising to 17. While the good news is that this virus is less lethal than previous coronaviruses, like SARS and MERS, we can’t be complacent as the fatality rate is likely to rise as more cases come to light.  

Coronaviruses infect many animals and cause common cold-like illness in man. Like SARS, 2019 nCoV has most likely come from a cross-over event from animals. A new paper out today suggests that that virus is the result of the mixing of two coronaviruses, one from bats and the other from an unknown species. The species might be snakes based on some DNA evidence. This is entirely possible but how it occurred is a mystery. It has happened before and will happen again. HIV came about the same way. Eating contaminated exotic meats is a clear way for this to occur. 

The 2019nCoV has a case fatality rate of ~3-5 per cent compared to MERS (26 per cent) and SARS (10 per cent). Any fatal virus is a concern but with good public health measures, such as early detection, isolation, and personal hygiene practises, this virus should not become a pandemic.  

It’s very likely Australia will get this virus arriving on our shores. The key is vigilance and quick action to limit its spread and therefore reduce potential deaths. Our Health authorities are doing all the right things to protect the public. 

If you are in an infected area protect yourself by washing hands regularly, limiting self-infection by wearing a facemask, and seeking medical help as soon as symptoms appear.

Last updated: 15 Apr 2020 5:51pm
Declared conflicts of interest:
None declared.
Professor Raina MacIntyre is Head of the Biosecurity Program at the Kirby Institute at the University of NSW. She is an expert in influenza and emerging infectious diseases.

How likely is it that the virus jumped from snakes to humans and how could this have happened?
"There is some evidence of this, but evidence is still emerging. With SARS, the animal culprit changed a few times until bats were finally identified as the source. Viruses can have more than one animal host, and viruses have been jumping the species barrier ever since we have been able to measure such jumps. Influenza is a case in point, with many animal and bird species as hosts. One study showed that over 70 per cent of new emerging infections in humans originate in animals."

What do we know about the virulence of the novel virus and how concerned should we be?
"The virulence is unclear, as the case and death numbers are changing daily. Based on public reports, it seems to be about 3 per cent. This is lower than SARS but much higher than influenza, even the pandemic of 2009."

The Brisbane man has now been found to be clear of the virus but how likely is it that Australia will see cases of the virus here?
"It is always possible we will see a travel-related case in Australia, and we have shown with MERS CoV that the risk for any country can be estimated based on the frequency of flight from the affected area. China is our most important trading partner and we have frequent travel between the two countries."

What can Australia do to avoid it and what can the individual do to protect themselves from it?
"The points at which prevention can occur are:

  1. Avoid travelling to affected areas, and avoid wet markets. If you do travel, report symptoms promptly.
  2. Airport screening as is being done in Australia with direct flights from Wuhan
  3. Health information to passengers from affected areas with clear instructions for reporting symptoms
  4. High alert in the health system to ensure that travel history is asked of anyone presenting with fever and cough. If they have travelled to China, infection control measures and isolation should be used until a diagnosis is made. Coronaviruses tend to cause hospital outbreaks.
  5. Health workers are at high risk of infection and death, as seen with SARS and MERS CoV. Several health workers were infected by this new virus from a single case, demonstrating that there may be super-spreader patients. It is essential that health workers have adequate personal protective equipment.
Last updated: 15 Apr 2020 5:33pm
Declared conflicts of interest:
None declared.
Dr Farhid Hemmatzadeh is an Associate Professor in Virology at the School of Animal and Veterinary Sciences at the University of Adelaide

Coronaviruses contain the largest genome among in all RNA viruses. It provides higher flexibility for them to adapt themselves to the different species or create new viruses.

Coronaviruses are common in human, cats, dogs, horses, pigs, cattle, camels, rabbits, ferrets, mink, rodents, birds, bats plus other birds and reptile and wildlife species. Coronaviruses regularly cause common cold in humans.

In one study in China, some kind of similarity has been detected between the genome of the snakes coronaviruses and new virus in human. It is too early to say this change was responsible for the establishment and spreading of this new coronavirus in human or snake was the source of this infection.

What do we know about the virulence of the novel virus and how concerned should we be?
"Due to the unique structure of the genome of the coronaviruses and their behaviour in human cells, it is highly likely to have new coronaviruses time to time in human or different species of animal.

The chance for transmission of the coronaviruses from animals to humans is not that high. But strong evidence exists to confirm transmission of some animal coronaviruses to human the well-known examples are SARS that transmitted from bats to cats then human and MERS that has a camel origin. When a coronavirus established in humans, the most possible way of transmission is human to human."

The Brisbane man has now been found to be clear of the virus but how likely is it that Australia will see cases of the virus here?
"The diagnostic tools and monitoring system are efficient enough to detect the viruses in clinically sick individuals, means if a sick person can be detectable at the point of the entry or even in flight. The biggest concern is the people who have been exposed to the virus but not showing the clinical signs yet are not detectable using the existing screening systems.

The incubation period for this infection is not well known and it is a possibility for a person been exposed to the virus a day or two before then, travel to different countries with no or minor signs then start shedding the virus to the others and spread the infection in different places."

What can Australia do to avoid it and what can individual do to protect themselves from it?
"Australia has one of the best biosecurity systems for incoming passengers. However, it is almost impossible to monitor all individuals coming to Australia mostly from China or neighbouring countries for coronaviruses. That means regarding the well-established biosecurity system in Australia, it is highly likely to be exposed to the new coronavirus. Until now, the virus has detected in China, Hong Kong, Thailand, South Korea, Japan, Taiwan, US.
More restricted screening system, more effective in-flight monitoring procedures and more effective responding to any suspected cases is highly recommended. 

Finally, the spreading pattern of the virus and recently released molecular studies showing that the human-human transmission of the virus is not as fast as the other acute respiratory viruses. and the chance for super-fast spreading of the virus is not as high as the other acute respiratory viruses like the 2009 outbreak of Swine flu. The World Health Organization's emergency committee hasn’t decided yet if it should be declared as an international public health emergency or not.

Last updated: 15 Apr 2020 5:08pm
Declared conflicts of interest:
None declared.
Associate Professor Rietie Venter is the Head of Microbiology at the University of South Australia

Ever since the Spanish Flu swept through post-war Europe and killed a larger number of people than even the Great War, pandemic virus outbreaks that would wipe out a significant proportion of the world’s population has stoked fear in the hearts of people. The new outbreak of 2019-nCoV in China is no exception.

There are some causes for concern. Firstly, this type of virus is spread by close human-human contact. Hence, dense co-habitation and international travel makes outbreaks harder to contain than outbreaks such as Ebola which spread through contact with contaminated bodily fluid.

Secondly, the recent discovery that snakes are the most probable wildlife animal reservoir for this virus (the first time that snake to human viral transmission has been observed) has implications for the possibility of other viral outbreaks linked to exotic pets or bushmeat.

However, medical epidemiology has progressed greatly in the 100 years since the Spanish Flu; all other viral outbreaks in the last century (Ebola, SARS, swine flu, MERS etc) were effectively contained with minimal loss of life. In addition, according to the WHO, the mortality rate of 2019-nCoV is very low (only about 3.8%). There is, therefore, no reason for panic and all reason to believe this outbreak will be similarly effectively dealt with.

Last updated: 15 Apr 2020 4:42pm
Declared conflicts of interest:
None declared.
Associate Professor Phill Cassey is Director of the Centre for Applied Conservation Science at the University of Adelaide and an expert in the live animal trade (www.cassey-invasion-ecology.org)

A bat and then snake origin for the novel coronavirus  is definitely a very interesting hypothesis. Regardless of whether it has an origin in snakes or not, it is highly likely to be zoonotic (a disease that spreads from animals to humans). One of the highest risk sources for exposure are wildlife and bushmeat markets, which constitute a massive risk for novel emerging diseases. Globally there is an increasing pressure for live animals (as well as products and derivatives) in the wildlife trade. In many cases the trade is unregulated and illegal with major risks to biodiversity and environments, including human health. Unfortunately, the illegal wildlife trade is a pervasive and increasing component of transnational environmental crime(1).

  1. Gore, M.L., Braszak, P., Brown, J., Cassey, P., Duffy, R., Fisher, J., Graham, J., Justo-Hanani, R., Kirkwood, A.E., Lunstrum, E. and Machalaba, C., 2019. Transnational environmental crime threatens sustainable development. Nature Sustainability2(9), pp.784-786.
Last updated: 15 Apr 2020 4:30pm
Declared conflicts of interest:
None declared.
Dr Mark O'Dea is a Senior Lecturer in Veterinary Virology at Murdoch University

I should point out that SARS coronavirus came from bats, and the Middle East Respiratory Syndrome Coronavirus originated from bats. It would not surprise me if the precursor to the current Wuhan coronavirus is also found in bats. There is a high level of viruses originating from bats which jump species into infecting humans - hence the study we did is important to human health.

Last updated: 15 Apr 2020 10:09am
Declared conflicts of interest:
None declared.
Professor Trevor Cullen is a Professor of Journalism within the School of Arts and Humanities at Edith Cowan University and an expert in how the media report on infectious diseases

Media reports on the coronavirus follow a similar sensational pattern.

Research has shown that if used effectively, the media can play an important role in lessening fear and stigma about existing and emerging infectious diseases. Yet, recent media coverage of the coronavirus, especially fear-mongering headlines, resemble how the media responded to HIV and Ebola – sensational, exaggerated and lacking facts.

Evidence of this can be seen in some of the recent newspaper headlines. For example, The West Australian’s front-page story (22 January) screams, "China Virus Code Red", while The Australian is slightly less dramatic with "Fears of China virus pandemic hit home", based on one case in Brisbane where the person is now back home. 

While scary, Armageddon-type headlines sell newspapers, the focus should return to what we know so far, and that’s very little. Write fact, not fiction.

Last updated: 07 Apr 2020 3:28pm
Declared conflicts of interest:
None declared.

Peter Daszak is President of EcoHealth Alliance in New York, a nonprofit organisation dedicated to protecting wildlife and public health from emerging diseases.

At EcoHealth Alliance, we haven’t seen evidence ample enough to suggest a snake reservoir for Wuhan coronavirus (2019-nCoV).

This work is really interesting, but when we compare the genetic sequence of this new virus with all other known coronaviruses, all of its closest relatives have origins in mammals, specifically bats. Therefore, without further details on testing of animals in the markets, it looks like we are no closer to knowing this virus’ natural reservoir. 

Meanwhile, we would like to point to what we already do know. Our work shows that human activities are the factors driving outbreaks like these: the wildlife trade creates unnatural interactions between people and wild animals, and this can allow the spread of viruses between the two.

We have seen how investment in prevention can be effective in the case of chronic diseases like heart and lung disease; EcoHealth Alliance encourages expanded investment in prevention when it comes to infectious diseases as well, so that we can work to stop diseases like this one before that start making people sick. This investment could be into better sanitation in markets, working to educate people on the risk of hunting, butchering and eating wildlife, better long term health surveillance for farmers and market workers in emerging disease hot-spots, and better surveillance for unknown viruses in wildlife. We need to do all of this prevention at the same time as we work on vaccines and drugs to cure the currently known viruses – that’s the best way to get ahead of pandemics.

Regarding the likelihood of cases arriving in Australia:
With funding from the US Dept of Defence, Defence Threat Reductions Agency, and from the Department of Homeland Security, we developed a Flight Risk Tracker tool that can calculate air traveller flows among airports, based on airplane capacity and a subset of actual traveller itineraries. This also calculates likely connecting flights.

Running this tool for travel from Wuhan over the current time period shows that there is a substantial risk of passengers arriving in SE Asian airports, but also a lower number of travellers to Australia. The risk of some of these passengers being infected is real, even after the travel ban out of Wuhan today, but of course, this can be dealt with by efficient surveillance at airports, quarantine and testing – something that the authorities in Australia are particularly well trained for.

Last updated: 24 Jan 2020 11:43am
Declared conflicts of interest:
None declared.
Associate Professor Sanjaya Senanayake is a specialist in Infectious Diseases and Associate Professor Of Medicine at The Australian National University

How likely is it that the virus jumped from snakes to humans and how could this have happened?
"It is highly likely that this virus jumped from animals. A study appears to have shown that the novel coronavirus seems to be a combination of two viruses: one from a bat and a snake. This is plausible since both snakes and bats can be found in live food markets in China.

The proximity of the live animals and humans in the market could have allowed the passage of the coronavirus. Also, the preparation and/or consumption of undercooked meat could also have allowed transmission of the coronavirus."

What do we know about the virulence of the novel virus and how concerned should we be?
"The mortality or death rate appears to be relatively low [around 3 per cent], when compared to other coronaviruses like SARS and MERS; however, if it turns out to be very infectious between people, then even a low death rate can still mean a large absolute number of deaths. And as the outbreak has progressed, concern about its infectivity has escalated, even within the last couple of days."

The Brisbane man has now been found to be clear of the virus but how likely is it that Australia will see cases of the virus here?
"One would think that it is highly likely to see cases in Australia, given our large Chinese diaspora and our proximity to China with multiple flights into the country. Interestingly, SARS, which also originated in China, only led to one probable case being diagnosed in Australia. But since 2004, one would imagine that travel between our two countries has increased a lot."

What can Australia do to avoid it and what can the individual do to protect themselves from it?
"At this stage, avoid travel to Hubei province, and probably China if possible. For Australians in China, avoid live markets, large gatherings and wash your hands as much as possible. Masks can be effective for short periods."

Last updated: 23 Jan 2020 5:10pm
Declared conflicts of interest:
None declared.

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