In bacteria and archaea, a CRISPR gene editing system exists.
It consists of a special CRISPR sequence, Cas protein and RNA that
This system is able to capture the genomic fragments of invading viruses and store the sequences in its own genome, so that when the same virus is encountered again, it can recognize and cut the corresponding DNA.
This system has also been adapted by scientists as an efficient gene editing tool.
In a recent study published in Cell, researchers found that some viruses in nature also possess the CRISPR system.
More than 6,000 viruses have been found to possess the system, and it covers all six known CRISPR-Cas types.
These CRISPR systems in viruses show a wide range of variations compared to the general CRISPR-Cas structure, for example, the CRISPR system in phages uses a very small Cas enzyme to cut DNA and is more easily delivered into cells.
The researchers speculate that because multiple viruses may attack the same bacteria at the same time, phages that “steal” the CRISPR system from their bacterial hosts can destroy competitors and gain a survival advantage.