Oxford University scientists find retroviruses are several hundred million years older than previously thought.
A new research by scientists at Oxford University shows retroviruses – he family of viruses that includes HIV – are almost half a billion years old and have ancient marine origins, having been with their animal hosts through the evolutionary transition from sea to land, according to a press release.
The ‘retro’ part of their name comes from the fact they are made of RNA, which they can convert into DNA and insert into their host genome – the opposite direction to the normal flow of information in a cell. This property means that they can occasionally be inherited as endogenous retroviruses (retroviruses with an internal origin), forming a virtual genomic fossil record that can be used to look back into their evolutionary history.
“Very little has been known about the ancient origin of retroviruses, partly because of the absence of geological fossil records. Retroviruses are broadly distributed among vertebrates and can also transmit between hosts, leading to novel diseases such as HIV, and they have been shown to be capable of leaping between distantly related hosts such as birds and mammals. But until now, it was thought that retroviruses were relative newcomers – possibly as recent as 100 million years in age. Our new research shows that retroviruses are at least 450 million years old, if not older, and that they must have originated together with, if not before, their vertebrate hosts in the early Paleozoic era. Furthermore, they would have been present in our vertebrate ancestors prior to the colonisation of land and have accompanied their hosts throughout this transition from sea to land, all the way up until the present day,” study author Dr Aris Katzourakis, from Oxford University’s Department of Zoology, said.
The findings are reported in the journal Nature Communications.