CRISPR tools found in thousands of viruses could boost gene editing

A systematic sweep of viral genomes has revealed a trove of potential CRISPR-based genome-editing tools.

CRISPR–Cas systems are common in the microbial world of bacteria and archaea, where they often help cells to fend off viruses. But an analysis¹ published on 23 November in Cell finds CRISPR–Cas systems in 0.4% of publicly available genome sequences from viruses that can infect these microbes. Researchers think that the viruses use CRISPR–Cas to compete with one another — and potentially to manipulate gene activity in their host to their advantage.

Some of these viral systems were capable of editing plant and mammalian genomes, and possess features — such as a compact structure and efficient editing — that could make them useful in the laboratory.

“This is a significant step forward in the discovery of the enormous diversity of CRISPR–Cas systems,” says computational biologist Kira Makarova at the US National Center for Biotechnology Information in Bethesda, Maryland. “There is a lot of novelty discovered here.”

DNA-cutting defences

Although best known as a tool used to alter genomes in the laboratory, CRISPR–Cas can function...