New report confirms retrovirus is ancient and half a billion years old

Oxford University

Retrovirus, a family of virus that includes HIV is being mapped. On January 10, 2017, a new study published in Nature Communications, by scientists at Oxford University found that retroviruses could be 500 million years old making medically and economically importance of this. The earlier data derived from mammalian and endogenous retroviruses estimated retroviruses to be ∼100 million years old. However, as evidenced by phylogenetic analyses of sparsely related EVRs, retroviruses are often involved in cross-species as well as across vertebrate classes. Thus, the evolutionary interaction between this viral group and their hosts appeared hundreds of millions years ago than previously thought.

Retroviruses are a group of viruses that turn their RNA into DNA and incorporate it into the genome of their host cells.

The findings indicate the movement of vertebrate hosts retroviruses from the ocean to dry land. By new mathematical calculation and modeling techniques, the correct age of an ancient line retrovirus called foamy viruses can be dated back 460 million and 550 million years ago.

Author Aris Katzourakis, a zoologist at Oxford says that “These findings show that this medically important group of viruses is at least up to half a billion years in age — far older than previously thought,” and these viruses are as old as vertebrates themselves, older than any other viruses we know about,”. 

The ancient retroviruses locked inside animal genomes, these viruses offer a window into infections that occurred millions of years ago.

Retroviruses, of which HIV is a modern example, infiltrated our genome long ago. RUSSELL KIGHTLEY / SCIENCE PHOTO LIBRARY

It is a revolution in medical science as previously it was very difficult to calculate the age of viruses as ancient as this because the natural accumulation of mutations in the viral genes clouding the micro-organisms’ early history.

Michael Worobey, an evolutionary virologist at the University of Arizona in Tucson says “You can see rapid evolution in retroviruses over short time frames, but this is a new evidence that they’ve been around for hundreds of millions of years,” and “we’re up against the limits of our ability to determine their age.

Robert Gifford at Rockefeller University in New York also supported and suggested that “People who are looking at the ecology of those diseases, work very much in recent time and they have no assumptions that it’s an old system that might have evolved over billions of years”.  “The data that we’re finding is really contradicting that and providing the first evidence that these are really old relationships between hosts and viruses, and I think it’s really critical to how we understand them to get that context right.” he further added.

“The mystery of origins of  retroviruses is closer to unravel to know their ultimate origin. “

Prof. Katzourakis believes the latest revelations will force scientists to adapt the way they interpret previous and ongoing studies of viral evolution. He said that “we need to consider the adaptations that vertebrates have developed to combat viruses, and the corresponding viral countermeasures, as the product of a continuous arms race that stretches back hundreds of millions of years”.

“It’s a really nice paper that uses the fact that almost every animal has a retrovirus, and their evolution occurred with these viruses,”. “You can’t consider the evolution of a species without the evolution of their pathogens.”

Source Nature Communications oxford University

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