It's tempting to treat gene editing as a cure-all: surely you can end diseases and viruses by changing or removing the qualities that make them dangerous, right? Well, it's not quite that simple. Researchers trying to cripple HIV by cutting up its DNA (using CRISPR) discovered that some virus samples not only survived the attack, but mutated to resist these incursions. The host T cell actually helped things along by trying to repair the cuts, inserting DNA bases and creating a mutated virus that couldn't be detected by the immune system.
That's frightening stuff, but the good news is that this isn't a permanent setback. The findings suggest that there are techniques you could use to beat HIV at its own game, such as making multiple cuts (preventing the virus from easily mutating) or using anti-HIV drugs at the same time as you edit genes. These improvements won't necessarily lead to a cure, but they suggest that HIV's adaptability is more of a temporary obstacle than a permanent barrier. This just serves as a reminder that gene editing is relatively new territory, and there are still many things to learn about how the procedure fares in the real world.