Written by Margaret Wei

Background

As carbon emissions increase annually, so too does the average world temperature. This is a result of the greenhouse effect as the emissions create heat, in which the sun rays are trapped in the earth’s atmosphere, preventing the accumulated heat from being released. The increase in temperature is a concern to scientists because viruses that were trapped in frozen arctic permafrost, preserved since the Ice Age thousands of years ago, can potentially make contact with humans (Mohan, 2014). Viruses enter host cells by penetrating through the cellular membranes, attaching to receptors, changing its viral proteins. In the end, the virus transfers its viral genomes inside host cells. Scientists are most concerned about the undiscovered capabilities of these viruses.

Discovery of the Mollivirus sibericum

The presence of the frozen viruses was first made known to the public in 2015; researchers Chantal Abergel and Jean-Michel Claverie of the French Centre National de la Recherche Scientifique uncovered the Mollivirus sibericum in 30,000 year old permafrost, and as they put it in their paper, “The fact that two different viruses retain their infectivity in prehistorical permafrost layers should be of concern in a context of global warming” (Wei, 2018). 

The microbe, described in the Proceedings of the National Academy of Sciences, appears to belong to a family of mega-viruses that exclusively infect amoebas, but its revival stands as “a proof of principle that we could eventually resurrect active infectious viruses from different periods,” said the study’s lead author, Jean-Michel Claverie (Mohan, 2014). The Mollivirus sibericum was visibly large under the microscope and it consisted of a significant amount of genetic material. 

A study in Alaskan permafrost was undertaken to learn more about the discovery and the potential impacts of global warming and permafrost thawing on metabolic pathways (Mooney, 2015). The researchers tested soils before and after thawing and found a rapid increase in activity after thawing due to the decomposition of soil organic matter. The thawing of permafrost leads to increased microbial activity and, as a result, increased emissions of greenhouse gases such as CO2, CH4, and N2O, which were previously trapped within (Collins, 2019). The increased methane emission resulted in a tenfold increase in the number of methanogenic archaea, as well as large changes in the composition and operations of archaeal communities.

Conclusion and Further Research

Although this was a groundbreaking discovery, this does not signify that it is likely for these viruses to use humans as their host organism. “All viruses tend to be very specific about their host species, so there is essentially no chance that the viruses they discovered will have any impact on human health,” stated Grant McFadden, a professor of molecular genetics and microbiology at the University of Florida and the former president of the American Society for Virology (Mooney, 2015). In addition, more research needs to be done in order to rule out the possibility that they could survive this long-term freezing and still infect their host, though it is questionable that they can last tens of thousands of years without a host.

A more pressing issue of the impact of global warming on pathology is the threat of the spread of vector-borne diseases, much less the melting permafrost. Organisms tend to migrate and follow unusual travel behavior in an environment where the temperature and climate are unstable. McFadden states that, “the wider global spread of insect vectors (particularly mosquitoes) and the viral pathogens they carry, compared to the real threat caused by ever increasing geographic ranges of vector-borne diseases like Dengue and Chikungunya viruses, the threat to human health of re-animated viruses from thawing permafrost is vanishingly small” (Wei, 2018).

References and Sources

Geoffrey Mohan. (2014). Ancient, frozen mega-virus is revived; If 30,000 years in Siberian permafrost didn’t kill it, human pathogens may lurk too, researchers say. The Los Angeles Times.

Margesin, R., & Collins, T. (2019). Microbial ecology of the cryosphere (glacial and permafrost habitats): current knowledge. Applied Microbiology and Biotechnology, 103(6), 2537–2549. https://doi.org/10.1007/s00253-019-09631-3

Chris Mooney. (2015). Why you shouldn’t freak out about ancient “Frankenviruses” emerging from Arctic permafrost: Of all the pandemic health risks we face, ancient Arctic viruses rank pretty low, say scientists. In Washington Post – Blogs. WP Company LLC d/b/a The Washington Post.

Wei, SP, Cui, HP, Zhu, YH, Lu, ZQ, Pang, SJ, Zhang, S, Dong, HL, Su, X: Shifts of methanogenic communities in response to permafrost thaw results in rising methane emissions and soil property changes. vol. 22, issue 3, pp. 447-459. Extremophiles (2018)