As the world charges to vaccinate the population against the coronavirus, gene therapy developers are locked in a counterintuitive race. Instead of training the immune system to recognize and combat a virus, they’re trying to do the opposite: designing viruses the body has never seen, and can’t fight back against.
It’s OK, really: These are adeno-associated viruses, which are common and rarely cause symptoms. That makes them the perfect vehicle for gene therapies, which aim to treat hereditary conditions caused by a single faulty gene. But they introduce a unique challenge: Because these viruses already circulate widely, patients’ immune systems may recognize the engineered vectors and clobber them into submission before they can do their job.