Hundreds of ancient viruses found in mammalian DNA
Scientists continue to discover new properties of junk DNA. This is a section of the genome that consists of genes that do not encode proteins. For a long time it was thought that it was completely useless, but recent studies refute this, reports Virus Evolution.
In a new study, a team from the University of New South Wales in Australia discovered that some of the “junk” genes are actually fragments of archaic viruses. They remained in our DNA after infections from our early ancestors. These fragments are called endogenous viral elements (computers).
Viral DNA makes up about 8% of the human genome. With its help, scientists can theoretically keep track of viral infections throughout the evolutionary history of our kind. But it remains unknown why they survived for such a long period.
“Over millions of years of evolution, DNA should have completely changed, but these 'fossils' have been preserved intact,” said paleovirologist Emma Harding.
To find the answer to this question, scientists analyzed the genomes of 13 species of marsupials, including the Tasmanian devil, Eugenia's kangaroo and marsupial mice. All samples revealed three types of viral particles: Bornaviridae, Filoviridae and Parvoviridae.
The study showed that the Bornaviridae virus first entered the DNA of animals back in the days of the dinosaurs, when South America and Australia were still a single land mass. It was believed that it originated about 100 million years ago, but as scientists have established, in fact, it is even older – it is about 160 million years old.
Some archaic viruses were still being transcribed into RNA. They could not code for proteins, but they were still involved in a number of cellular functions.
Scientists have concluded that, among other things, ancient viruses contribute to the immune defense against infection. For example, bats, which are known for their ability to resist virus attacks, have a particularly large supply of computers.
“It can be a mechanism similar to vaccination, but inherited from generation to generation. By preserving the ancient virus, the cell is immunized against future infection, ”the authors emphasized.
Earlier it was reported that a new coronavirus was detected in bats in Asia. It was found in bats from a nature reserve in Thailand.
