HIV is apparently even older than scientists thought. Previous research had suggested retroviruses, the family of viruses that include HIV, were around 60 to 100 million years old, and may have even co-existed with dinosaurs. New research from Oxford University now shows they are much, much older; 450 million years or older, predating dinosaurs and even land itself. (Retroviruses really deserve an "older than the hills" designation, as they emerged from earth's early oceans.)
In the new analysis, published in Nature Communications, Dr. Aris Katzourakis from Oxford University’s Department of Zoology argues retroviruses "have originated together with, if not before, their vertebrate hosts in the early Paleozoic era." In a statement, he added, “Furthermore, they would have been present in our vertebrate ancestors prior to the colonization of land and have accompanied their hosts throughout this transition from sea to land, all the way up until the present day.”
Little had been known about the ancient origin of retroviruses because there are virtually no fossil records to study. They are microscopic and often bloodborne, neither of which tended to draw our attention, even if they did fossilize. In the past, fossil hunters tended to look for bones. Big bones.
In case you didn’t know, HIV is part of a family of viruses called retroviruses, which also include various kinds of cancers and immunodeficiencies. The reason for the “retro” is because they are made of RNA, which then converts into DNA, thus becoming part of a host’s genome. As a result, they can be tracked through historic fossil records.
Researchers took genomic fossils found in various hosts, including ray-finned fish and amphibians they’d not discovered before. But the key conflict in researching such evolutionary history was diverting past the virus’s rapid evolution, which is always tricky.
According to Nature, the researchers used "new mathematical techniques to calculate the age of an ancient line of retroviruses called foamy viruses, which infect species ranging from lemurs to fish, the researchers worked out that retroviruses first evolved between 460 million and 550 million years ago."
“[Retroviruses] date back to the origins of vertebrates,” Dr. Katzourakis added, “and this gives us the context in which we should consider their present-day activity and interactions with their hosts. For example, 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.”
Ironically, it was also discovered by researchers that retroviruses played an important role for our bodies to adapt immunity from other viruses. So despite the fact that they gave us fatal kinds of diseases, they also built our bodyies' mainframes to combat other kinds of sicknesses — a catch 22. Pervious studies have found that 8 percent of the human genome consists of retroviral elements, although many of them now inert.
Moving forward, these discoveries will help us understand the intricate relationships viruses have with our bodies' immune systems, thus allowing greater insight towards future breakthroughs in treatment and intervention for fighting retroviruses like HIV.