Curing HIV just got more complicated. Can CRISPR help?

ntiretroviral (ARV) drugs have turned HIV infection from a death sentence to a chronic condition. In most people the drugs routinely tamp HIV levels so low that standard tests find no virus in blood samples. But inexplicably, in about 10% of infected people HIV remains easily detectable in the blood even though they take their daily pills and are not saddled with drug-resistant mutants of the virus.

A study presented last week at the largest annual U.S. HIV/AIDS conference offers a solution to this riddle: “repliclones,” populations of replicating cells with HIV’s genome nestled inside them. “It’s the most interesting presentation I’ve seen here,” says George Pavlakis, a retrovirologist at the National Cancer Institute in Frederick, Maryland.

These repliclones highlight what might be a serious shortcoming in a popular HIV cure strategy. They are also drawing new attention to a radical approach for extirpating persistent virus: using the genome editor CRISPR to cut HIV’s genes out of infected cells. A monkey study of the approach presented at the same meeting showed signs of success, and a biotech company is now hoping to launch a clinical trial.