In a plot that sounds like something out of a low-budget horror film, scientists have recently uncovered ancient, enormous viruses in ice that some say could wake up as the Earth’s climate warms.
Before they begin to threaten our health, however, some of these newly-unearthed viruses may offer important clues into some of the most enduring biological mysteries – including where such viruses came from in the first place.
This week scientists at the University of New South Wales in Australia found a microorganism in the lakes off the coast of Antarctica that could offer clues as to how the first viruses – which include HIV and even the virus that causes the common cold – came to be. They believe they may have broken out of some of the oldest cells on Earth. The findings are detailed in a paper in the journal Nature Microbiology.
Deep in the lakes of a group of rocky, coastal islands near the south pole, the researchers uncovered an organism that resembles a bacterium, but is not. In reality, the lifeform belongs to a separate class of life known as Archaea, a type of single-celled organism that typically thrives in harsh environments. The most intriguing finding, however, came from even further inside the organism’s cells – where a scientists uncovered a tiny piece of self-replicating DNA.
Fragments like these are known as plasmids. Typically, they carry bits of genetic material that could be of use to the cells they live inside. This plasmid, however, was a strange specimen. Instead of remaining trapped inside its host cell like most plasmids, the plasmid (which they named pR1SE) was able to break free. By encasing itself in a protective bubble made of fat, pR1SE could hop out of its host cell – maybe even looking for other cells to occupy.
It’s a behavior that is eerily similar to that of viruses.
“pR1SE looks and acts a lot like a virus. But it carries genes that are found only on plasmids, and lacks any telltale virus genes. It is a plasmid with the attributes of a virus,” wrote Michael Marshall in a recent article for New Scientist.
In other words, pR1SE could be the missing link between tiny bits of DNA and viruses, potentially solving one of the greatest scientific mysteries of the past century.