Reviving ancient viruses seems to be the new cool for scientists. Awakening frozen subarctic viruses has been the subject of a few studies this year; the extreme cold temperatures and environmental conditions of the polar and subpolar regions are conducive for the conservation of life at the microscopic level, to such an extent that decades later, some organisms can be made to live again.
Earlier this year, in March, scientists had reanimated a 30 000-year-old virus obtained from Siberia. Yet other researchers had had a species of moss previously buried in the Antarctica ice ‘brought back to life’ as well. Now, another team of scientists have reconstituted a viral genome harvested from caribou faeces dating back several hundreds of years ago.
The study entitled “Preservation of viral genomes in 700-y-old caribou feces from a subarctic ice patch” reveals how ancient viruses can be preserved for an extremely long period of time.
A permanent ice patch in Canada had embedded in it layers of caribou faeces that had accumulated over long periods of time. A group of scientists drilled through these layers and spotted the genetic material of a virus that had been preserved in the 700-year-old ice. The caribous are known to egest plant material together with viruses – the mixture of which can remain frozen for thousands of years. The viruses were then protected in the cold inside viral capsids that act like shields.
A complete small circular genome of a DNA virus was thus isolated. The make-up of the DNA suggests that the virus is a distant relative of some contemporary plant and fungi viruses.
The viruses might have come from the plants consumed by the caribous, or from insects that have delved into the faeces of the caribou.
To determine whether the virus can infect plants, the scientists inserted the ancient viral DNA into the plant Nicotiana benthamiana. The observations made afterwards showed that the virus can, in fact, infect plants, as the DNA of the virus was seen to replicate and propagate itself throughout the leaves of the plant.
The virus is not deemed to be potentially harmful to humans. They might emerge in the future though, as more ice melts exposing more caribou faeces thus conserved. This might lead to the infiltration of other ancient viruses into our atmosphere.