“Trash” genes, which are quite a lot of mammalian genomes, in many cases are fragments of ancient viruses. Such a discovery, according to the thematic publication Virus Evolution, was made by Australian scientists representing the University of New South Wales.
Scientists are accustomed to calling “junk” DNA the sections of the genome consisting of genes that do not code for proteins. For decades, “junk” DNA was thought to be a byproduct of evolution and of no practical use, but in recent years, researchers have begun to question this.
A new study shows that some “junk” DNA fragments in mammals are scraps of archaic viruses that plagued the distant ancestors of modern species. Such DNA fragments have been called “endogenous viral elements” (EVMs).
As paleovirus scientist Emma Harding noted, scientists still don’t understand why scraps of ancient viruses persist in DNA for so long. “Over millions of years of evolution, no trace should have been left of these ‘fossils,’ but we see that this is not the case,” the researcher said, adding that scientists have studied the genomes of 13 marsupial species in search of EVMs, and found particles of at least three ancient viruses – Bornaviridae, Filoviridae and Parvoviridae.