The discussion about global warming is usually around adverse climatic changes caused by the trapping of greenhouse gases such as carbon dioxide in the earth's atmosphere, which primarily affects biodiversity and contributes to serious health hazards.
It is also seen that increase in heat, precipitation, and humidity could allow tropical and subtropical insects to move from regions where infectious diseases thrive into new places. Over a period of many years, it has been seen that the combined impacts of demographic, environmental, social, as well as climatic changes affect infectious disease occurrence.
AdvertisementOne of the researchers from the University of California, San Francisco, Eric Delwart and his colleagues has discovered an entire plant virus inside a caribou feces which was nearly 700 years old. They studied the frozen samples of caribou feces, which were collected from the icy patches in the Selwyn mountains of the Yukon and Northern Territories.
The presence of the viruses in the fecal samples suggest that it could have originated in plants eaten by the caribou or flying insects attracted to the material. It is believed that the caribou used patches of ice to get from relief from the irritating effects of ticks and insects, in this way their copious feces, which contain partially digested plant material, became preserved when layers of ice accumulated above it.
The scientists analyzed the viral genetic material and separated the complete genome of this DNA virus which was distantly related to plant and fungi-infecting viruses. They also isolated a partial viral RNA genome which was related to an insect-infecting cripavirus. They then reconstituted the genome of the DNA virus using a reverse genetics approach. The method is also known as "viral particle-associated nucleic acid enrichment".
In their effort to study the potential of this virus in infecting plants, they introduced it to one of the close relative of tobacco, namely Nicotiana benthamiana, and upon further studies discovered that it successfully infected both new leaves and leaves inoculated with the virus.
The question was as to how the virus survived for hundreds of years in such extreme cold conditions to which Delwart explained that the virus was actually protected by a tough coat, rock-hard material called as capsid. He thought that whilst the capsid shielded and protected the virus, the freezing cold temperatures self-preserved the virus.
It is not easy to recreate ancient viruses because they are most often poorly preserved, partially degraded and also their concentration is quite low. However such viruses isolated from ancient samples provide valuable information not only about viral diversity in those times but also help in finding the evolution of species and study their biology.
The team of scientists felt that their research is quite promising and shows the potential for bringing back other viruses to study and work out how to beat them. They believe that cryogenically preserved materials can be repositories of ancient viral nucleic acids, then with the help of molecular genetics, they could regenerate viruses and study their biology.
Jean-Michel Claverie of the Aix-Marseille University School of Medicine in France commented "The find confirms that virus particles are very good 'time capsules' that preserve their core genomic material, making it likely that many prehistoric viruses are still infectious to plants, animals or humans. This again calls for some caution before starting to drill and mine Arctic regions at industrial scales."
The scientists believe that this should be considered as a pre warning sign because as the Arctic ice and snow melts faster with climate change, it could revive and release ancient viral particles into the air or the environment, some of which could be potentially infectious. Such revival of these viruses could lead to unforeseen consequences both for people and for wildlife.