In 1859, Charles Darwin published On the Origin of Species and proposed his idea of evolution by natural selection. That was before the field of genetics and the structure of DNA was even discovered. Darwin stated that it was the environment that “selects” organisms for better fitness which eventually leads to evolution. But imagine Darwin’s “surprise” were he to find out that unseeable infectious factors, viruses, have been contributing to our evolution and the evolution of numerous other species for millions of years. Aside from the shock that stems from the idea that something like viruses even exists, I’d imagine Darwin would be amazed at how such a basic being can so intrinsically change a species, even directly altering their genome. I suppose that under further analysis, viruses (not even alive) is a part of nature and, as such, should be considered a selective pressure no matter how unique their method of selection might seem.
It’s undoubted that viruses have greatly influenced many species over the course of life’s history (or else we wouldn’t be feeling the effects of HIV today). The many retroviruses that have existed, mutating and inserting their genes into ours, have no doubt played a major role in making us (genetically speaking, of course) who we are. Viral genes that have become our own can and have directly affected us by contributing to our protein syntheses but just because a viral gene is never used for anything doesn’t mean it will never affect us in the future. If there’s anything PtERV and HIV have taught us is that (and I’ll just say it): even extinct viruses can come back to bite us in the butt. I was surprised to learn that a virus humans fought off ages ago (which at first seemed like a good thing), and certain primates weren’t able to, actually contributed to our lack of defenses against HIV. I believe this is a prime example of how genetic variation that came about millennia ago, if it didn’t affect us then, can influence our survivorship much later. (I suppose a good analogy would be to imagine a silent mutation that did nothing in the past but might do something in the future.)
As for the ethicality of “reviving” dead viruses, in a way, it’s incomparable to the idea of Frankenstein or Jurassic Park, but only if people continue to take responsibility for what they’ve done. After all, scientists aren’t simply recreating a virus because they can. They’re doing so because valuable insight can be gained from these viruses (which is very different from creating dinosaurs for an amusement park). And they have taken precautionary measures to ensure the viruses don’t simply escape back into the world again (i.e. making sure the virus replicated only once). Responsibility is key and that includes having a proper reason to revive a virus, dangerous or not, and to ensure that the virus can cause no accidents once revived.