They’ve been dormant for millions of years, yet are impacting life today, in a big way.
No, it’s not the zombie apocalypse. Perhaps even more strikingly, it is the impact of endogenous viruses on the lives of humans and other organisms around the world. Comprising eight percent of our present genome – four times more than the amount of genetic material that create all of our necessary proteins – these old, broken viral DNA segments have major implications on our functioning as humans – many of which are still unknown.
Take, for example, the fact that chimpanzees and gorillas – our recent common ancestors – are immune to perhaps the most ambitiously studied retrovirus of present – HIV. The mysterious defender? Yet another ancient retrovirus, known as PtERV. Already having been incorporated into their genome, PtERV coded for proteins that provided HIV resistance. Humans, luckily (or unluckily) never were infected by PtERV – thus, when confronted with both it and HIV, the body developed PtERV immunity, leaving HIV without opposition. To study it, the PtERV virus has been biologically re-created, and may prove to be the first step in developing some sort of HIV resistance.
In taking a step back, and examining this finding from a greater lens, one cannot ignore the infinite doors this technique can take us through – these viruses, to a large extent, have played an extraordinarily important role in organismal development…one just now being fully recognized. Indeed, they are the remnants of past wars of evolutionary one-upmanship – our genetic material simply the battlefield, made even more complex by the sprinkling of new abilities, proteins, and reactions over the millions of years. So what specifically will come from these ‘walking dinosaurs’? Surely, we will be able to paint a picture of both our past, and future – but what are the specifics?
In terms of events that occurred long ago, we can pinpoint moments of speciation, possible causes for extinction, the development of certain genes, and identify – as is the case with chimpanzees – how immunities have developed. The future, too, seems full of opportunity. What viruses of today will change the humans of tomorrow – how will we look, act, and respond in another million years? How can these viruses be artificially modified in organismal genomes, for good and for bad – bio-luminescent trees to save electricity, viral warfare?
It is clear that these viruses are major keys in unlocking a slew of biological secrets we didn’t even know the body had kept. Just a few decades ago, these ‘dead’ viruses were regarded as junk DNA with little importance. A few decades from now, these hidden gems will once again direct the discovery of a whole new realm of biological inquiry.