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Clinical Laboratories and Pathology Groups

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Scientists Revive and Characterize 13 Ancient “Zombie” Viruses Isolated from Siberian Permafrost

Viruses are between 27,000 to 48,500 years old and not dangerous, but researchers say thawing permafrost may one day release pathogens capable of infecting humans

Last fall, European researchers working with virologists and genetic scientists at the Aix-Marseille University in France reported having revived and characterized 13 previously unknown “zombie” viruses isolated from Siberian permafrost samples, including one that was almost 50,000 years old. This will be of particular interest to microbiologists and clinical laboratory managers since these organisms are new to science and may be precursors to infectious agents active in the world today.

The work of the European scientists demonstrates how advancements in genome sequencing and analysis of DNA data are becoming, faster, less expensive, and more precise. That’s good because the researchers warned that, should the permafrost continue to thaw, other previously dormant viruses could be released, posing potential risks for public health.

The scientists published their findings in the open-access journal Viruses titled, “An Update on Eukaryotic Viruses Revived from Ancient Permafrost.”

The pathogens isolated by the researchers are so-called “giant viruses” that infect Acanthamoeba, a commonly found genus of amoeba, and thus are not likely to pose an immediate health threat, the researchers wrote.

However, the scientists expressed concern. “We believe our results with Acanthamoeba-infecting viruses can be extrapolated to many other DNA viruses capable of infecting humans or animals. It is thus likely that ancient permafrost … will release these unknown viruses upon thawing,” they stated in their Viruses paper.

It’s unknown how long the viruses “could be infectious once exposed to outdoor conditions (UV light, oxygen, heat), and how likely they will be to encounter and infect a suitable host in the interval,” they added. However, “the risk is bound to increase in the context of global warming, in which permafrost thawing will keep accelerating, and more people will populate the Arctic in the wake of industrial ventures.”

Paulo Verardi, PhD

“In nature we have a big natural freezer, which is the Siberian permafrost,” virologist Paulo Verardi, PhD (above), head of the Department of Pathobiology and Veterinary Science at the University of Connecticut, told The Washington Post. “And that can be a little bit concerning.” However, “if you do the risk assessment, this is very low. We have many more things to worry about right now.” Nevertheless, clinical laboratories may want to remain vigilant. (Photo copyright: University of Connecticut.)

Extremely Old, Very Large Viruses

The newly discovered viruses were found in seven different permafrost samples. Radiocarbon dating determined that they had been dormant for 27,000 to 48,500 years. But viruses contained in permafrost could be even older, the researchers wrote, as the time limit is “solely dictated by the validity range of radiocarbon dating.”

In their Viruses paper, the researchers noted that most of the 13 viruses are “at a preliminary stage of characterization,” and others have been isolated in the research laboratory “but not yet published, pending their complete genome assembly, annotation, or detailed analysis.”

“Every time we look, we will find a virus,” study co-author Jean-Michel Claverie, PhD, told The Washington Post. “It’s a done deal. We know that every time we’re going to look for viruses—infectious viruses in permafrost—we are going to find some.”

Claverie is a professor emeritus of genomics and bioinformatics in the School of Medicine at Aix-Marseille Université in Marseille, France. He leads a university laboratory known for its work in “paleovirology,” and in 2003, discovered the first known giant virus, dubbed Mimivirus. The research team included scientists from Germany and Russia.

According to CNN, unlike regular viruses that generally require an electron microscope to be viewed, giant viruses can be seen under a standard light (optical) microscope. Claverie’s laboratory previously isolated giant viruses from permafrost in 2014 and 2015.

Protecting Against Accidental Infection

To demonstrate the infectious potential of the viruses, the researchers inserted the microbes into cultured amoeba cells, which the researchers describes as “virus bait,” The Washington Post reported. One advantage of using Acanthamoeba cultures is to maintain “biological security,” the researchers wrote in their paper.

“We are using [the amoeba’s] billion years of evolutionary distance with human and other mammals as the best possible protection against an accidental infection of laboratory workers or the spread of a dreadful virus once infecting Pleistocene mammals to their contemporary relatives,” the paper noted. “The biohazard associated with reviving prehistorical amoeba-infecting viruses is thus totally negligible compared to the search for ‘paleoviruses’ directly from permafrost-preserved remains of mammoths, woolly rhinoceros, or prehistoric horses.”

The paper cites earlier research noting the presence of bacteria in ancient permafrost samples, “a significant proportion of which are thought to be alive.” These include relatives of contemporary pathogens such as:

How Dangerous are Ancient Viruses?

“We can reasonably hope that an epidemic caused by a revived prehistoric pathogenic bacterium could be quickly controlled by the modern antibiotics at our disposal,” the researchers wrote, but “the situation would be much more disastrous in the case of plant, animal, or human diseases caused by the revival of an ancient unknown virus.”

However, according to The Washington Post, “Virologists who were not involved in the research said the specter of future pandemics being unleashed from the Siberian steppe ranks low on the list of current public health threats. Most new—or ancient—viruses are not dangerous, and the ones that survive the deep freeze for thousands of years tend not to be in the category of coronaviruses and other highly infectious viruses that lead to pandemics.”

Cornell University virologist Colin Parrish, PhD, President of the American Society for Virology, told The Washington Post that an ancient virus “seems like a low risk compared to the large numbers of viruses that are circulating among vertebrates around the world, and that have proven to be real threats in the past, and where similar events could happen in the future, as we still lack a framework for recognizing those ahead of time.”

Anthony Fauci, MD, former Director of the National Institute of Allergy and Infectious Diseases (NIAID), responded to an earlier study from Claverie’s lab by outlining all the unlikely events that would have to transpire for one of these viruses to cause a pandemic. “The permafrost virus must be able to infect humans, it must then [cause disease], and it must be able to spread efficiently from human to human,” he told The Washington Post in 2015. “This can happen, but it is very unlikely.”

Thus, clinical laboratories probably won’t see new diagnostic testing to identify ancient viruses anytime soon. But it’s always best to remain vigilant.

Stephen Beale

Related Information:

Scientists Have Revived a ‘Zombie’ Virus That Spent 48,500 Years Frozen in Permafrost

‘Zombie’ Viruses Are Thawing in Melting Permafrost Because of Climate Change

Ancient Dormant Viruses Found in Permafrost, Once Revived, Can Infect Amoeba

Scientists Revive 48,500-Year-Old ‘Zombie Virus’ Buried in Ice

Scientists Revived Ancient ‘Zombie Viruses’ Frozen for Eons in Siberia

Scientists Warn Long-Frozen ‘Zombie Virus’ Is ‘Public Health Threat’ Amid Thaw

Scientists Did Not Release a Zombie Plague by Reviving a Dormant Virus, but Their Warning of a Potential Public Health Crisis Is Legitimate

Will ‘Flurona” Be an Issue for Clinical Laboratories This Flu Season?

Epidemiologists warn that elderly and other individuals may be at high-risk for co-infection by strains of both SAR-CoV-2 and influenza

As of October, the influenza (flu) season has begun in North America. With the COVID-19 pandemic still prevalent, clinical laboratories must be prepared not only for increased demand for SARS-CoV-2 tests, but also for an increased number of orders for flu tests as well. In fact, virologists are sounding the alarm that some patients may present with an uncommon double infection of both viruses.

The potential for contracting the co-infection was dubbed “flurona” by the Israeli Outbreak Management Advisory Team in 2020. The Israeli Team coined the term flurona to describe the potential of contracting both COVID-19 and influenza after two young Israeli pregnant women were diagnosed with influenza and COVID-19. Since then, cases of co-infections have been confirmed in multiple countries around the world, according to The Washington Post.  

The symptoms of influenza and COVID-19 are extremely similar. According to the Centers for Disease Control and Prevention (CDC), symptoms for both influenza and COVID-19 include fever, cough, chills, sore throat, and body aches. However, without a clinical laboratory test it is nearly impossible to distinguish one virus from the other.

Therefore, during this cold and flu season, clinical laboratory testing will be extremely important. And though co-infection with COVID-19 and the flu is rare, lab leaders should be on the lookout for spikes in testing.

Stephen McMullan, MD

“Co-infection is rare with COVID-19 and the flu, or COVID-19 and other types of infections that you might get as far as upper respiratory infections, because COVID-19 tends to take over,” Stephen McMullan, MD, a Mayo Clinic family medicine physician, told Mayo Clinic News. “Once COVID-19 is in your body, it’s going to be the predominant virus, but there are some rare cases where we have seen people getting both COVID-19 and the flu. So, it is possible, but it’s certainly not common.” Clinical laboratories should prepare for a spike in viral infections this winter that could indicate flurona. (Photo copyright: Mayo Clinic.)


What Exactly Is a Flurona?

Although it is possible—albeit rare—to contract the flu and COVID-19 at the same time, flurona does not appear to be a “twindemic,” nor is it a distinct disease or a mutation of the two viruses, The Washington Post reported.

“The name seems to suggest that the viruses have somehow combined—and that’s not the case. It’s just that a person may get infected with two respiratory viruses at the same time or in short succession,” epidemiologist Judith O’Donnell, MD, Director, Department of Infection Prevention and Control, and Section Chief, Division of Infectious Diseases at Penn Presbyterian Medical Center, told an NPR affiliate in Pittsburg.

“It’s rare, but it’s not surprising that during a typical influenza season—which here in the northern hemisphere is right now during the winter months—that you will see multiple respiratory viruses circulating at the same time, and that people can get infected with more than one respiratory virus at the same time,” she added.

Though flurona may not be a hybrid virus, that does not mean it is of no concern.

“Although a low proportion of COVID-19 patients have influenza co-infection, the importance of such co-infection, especially in high-risk individuals and the elderly, cannot be ignored,” wrote the authors of a study published in Frontiers of Medicine titled, “COVID-19 and Influenza Co-infection: A Systematic Review and Meta-Analysis.”

Did COVID-19 Lockdowns, Social Distancing Cause Flurona?

According to the Washington Post, the US had record lows of influenza during the 2020-2021 flu season, however this was likely due to lockdown measures. With lockdown measures and social distancing even less prevalent this flu season, there is a risk of individuals being at risk for multiple respiratory viruses.

“We’re all a little bit more back together than we were a year ago,” McMullan told Mayo Clinic News. “The kids are back in school, and we have more events that people are attending, which could explain why we’re seeing flu cases rise.”

Thus, clinical laboratories should prepare for not only a higher number of flu tests, but also COVID-19 tests as well. That is because patients will not be able to distinguish which virus they are sick with based on symptoms alone. Further, because COVID-19 and the flu have similar symptoms, individuals may seek out multiple tests, or test for one virus and not the other.

McMullan asserts that a co-infection of the flu and COVID-19—though rare—is not impossible. For the best chance to avoid both diseases he suggests high-risk individuals “Get vaccinated against COVID-19, including your booster if eligible, and make sure to get your flu vaccine, continue to do the same strategies to protect yourself and others, such as wearing a mask in high-risk situations, washing your hands, and staying home if you feel ill.”

Meanwhile, clinical laboratory managers will want to track developments during this flu season. For example, flurona may be uncommon at this time, but emerging variants of SARS-CoV-2 and different strains of influenza might increase the number of patients diagnosed as infected with both COVID-19 and influenza.

Ashley Croce

Related Information:

What Is ‘Flurona’? Israel Reports First Case of Rare Double Covid and Flu Infection

Similarities and Differences between Flu and COVID-19

What Is ‘Flurona’ and Why a Mayo Clinic Expert Says Flu Cases Are Rising

What Is ‘Flurona’? Coronavirus and Influenza Co-Infections Reported as Omicron Surges

CDC: COVID Data Tracker Weekly Review

The Double-Whammy COVID-Flu

What to Know about ‘Flurona’

Getting COVID-19 and the Flu at the Same Time: What Are the Risks?

Rates of Co-infection Between SARS-CoV-2 and Other Respiratory Pathogens

AHA: Flurona and Its Impact on Flu Season

COVID-19 and Influenza Co-infection: A Systematic Review and Meta-Analysis

What Is ‘Flurona’? Why Are People Talking about It Now?

Fact Check-‘Flurona’ Is Not the Name of a New SARS-CoV-2 Variant