Researchers at the University of California have used CRISPR/Cas9 a popular genome editing technique to precisely modify a key type of human immune cell that protects the body against a wide range of diseases, from diabetes to AIDS to cancer. They were able to disable a protein on the T-cell surface called CXCR4, which can be exploited by HIV when the virus infects T cells and causes AIDS.

The team also successfully shut down PD-1, a protein that has attracted intense interest in the burgeoning field of cancer immunotherapy, as scientists have shown that using drugs to block PD-1 coaxes T cells to attack tumours.

The gene-editing system CRISPR/Cas9 has captured the imagination of both scientists and the general public because it makes it possible to easily and inexpensively edit genetic information in virtually any organism. Cas9, an enzyme in the CRISPR system that makes cuts in DNA and allows new genetic sequences to be inserted, has generally been introduced into cells using viruses or circular bits of DNA called plasmids.